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trace.c

/*
 * ring buffer based function tracer
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
 *
 * Originally taken from the RT patch by:
 *    Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Based on code from the latency_tracer, that is:
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 William Lee Irwin III
 */
#include <linux/ring_buffer.h>
#include <linux/utsrelease.h>
#include <linux/stacktrace.h>
#include <linux/writeback.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/smp_lock.h>
#include <linux/notifier.h>
#include <linux/irqflags.h>
#include <linux/debugfs.h>
#include <linux/pagemap.h>
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/splice.h>
#include <linux/kdebug.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/gfp.h>
#include <linux/fs.h>

#include "trace.h"
#include "trace_output.h"

#define TRACE_BUFFER_FLAGS    (RB_FL_OVERWRITE)

unsigned long __read_mostly   tracing_max_latency;
unsigned long __read_mostly   tracing_thresh;

/*
 * On boot up, the ring buffer is set to the minimum size, so that
 * we do not waste memory on systems that are not using tracing.
 */
static int ring_buffer_expanded;

/*
 * We need to change this state when a selftest is running.
 * A selftest will lurk into the ring-buffer to count the
 * entries inserted during the selftest although some concurrent
 * insertions into the ring-buffer such as trace_printk could occurred
 * at the same time, giving false positive or negative results.
 */
static bool __read_mostly tracing_selftest_running;

/*
 * If a tracer is running, we do not want to run SELFTEST.
 */
static bool __read_mostly tracing_selftest_disabled;

/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
      { }
};

static struct tracer_flags dummy_tracer_flags = {
      .val = 0,
      .opts = dummy_tracer_opt
};

static int dummy_set_flag(u32 old_flags, u32 bit, int set)
{
      return 0;
}

/*
 * Kill all tracing for good (never come back).
 * It is initialized to 1 but will turn to zero if the initialization
 * of the tracer is successful. But that is the only place that sets
 * this back to zero.
 */
static int tracing_disabled = 1;

static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);

static inline void ftrace_disable_cpu(void)
{
      preempt_disable();
      local_inc(&__get_cpu_var(ftrace_cpu_disabled));
}

static inline void ftrace_enable_cpu(void)
{
      local_dec(&__get_cpu_var(ftrace_cpu_disabled));
      preempt_enable();
}

static cpumask_var_t __read_mostly  tracing_buffer_mask;

/* Define which cpu buffers are currently read in trace_pipe */
static cpumask_var_t                tracing_reader_cpumask;

#define for_each_tracing_cpu(cpu)   \
      for_each_cpu(cpu, tracing_buffer_mask)

/*
 * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
 *
 * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
 * is set, then ftrace_dump is called. This will output the contents
 * of the ftrace buffers to the console.  This is very useful for
 * capturing traces that lead to crashes and outputing it to a
 * serial console.
 *
 * It is default off, but you can enable it with either specifying
 * "ftrace_dump_on_oops" in the kernel command line, or setting
 * /proc/sys/kernel/ftrace_dump_on_oops to true.
 */
int ftrace_dump_on_oops;

static int tracing_set_tracer(const char *buf);

#define BOOTUP_TRACER_SIZE          100
static char bootup_tracer_buf[BOOTUP_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;

static int __init set_ftrace(char *str)
{
      strncpy(bootup_tracer_buf, str, BOOTUP_TRACER_SIZE);
      default_bootup_tracer = bootup_tracer_buf;
      /* We are using ftrace early, expand it */
      ring_buffer_expanded = 1;
      return 1;
}
__setup("ftrace=", set_ftrace);

static int __init set_ftrace_dump_on_oops(char *str)
{
      ftrace_dump_on_oops = 1;
      return 1;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);

unsigned long long ns2usecs(cycle_t nsec)
{
      nsec += 500;
      do_div(nsec, 1000);
      return nsec;
}

/*
 * The global_trace is the descriptor that holds the tracing
 * buffers for the live tracing. For each CPU, it contains
 * a link list of pages that will store trace entries. The
 * page descriptor of the pages in the memory is used to hold
 * the link list by linking the lru item in the page descriptor
 * to each of the pages in the buffer per CPU.
 *
 * For each active CPU there is a data field that holds the
 * pages for the buffer for that CPU. Each CPU has the same number
 * of pages allocated for its buffer.
 */
static struct trace_array     global_trace;

static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);

int filter_current_check_discard(struct ftrace_event_call *call, void *rec,
                         struct ring_buffer_event *event)
{
      return filter_check_discard(call, rec, global_trace.buffer, event);
}
EXPORT_SYMBOL_GPL(filter_current_check_discard);

cycle_t ftrace_now(int cpu)
{
      u64 ts;

      /* Early boot up does not have a buffer yet */
      if (!global_trace.buffer)
            return trace_clock_local();

      ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
      ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);

      return ts;
}

/*
 * The max_tr is used to snapshot the global_trace when a maximum
 * latency is reached. Some tracers will use this to store a maximum
 * trace while it continues examining live traces.
 *
 * The buffers for the max_tr are set up the same as the global_trace.
 * When a snapshot is taken, the link list of the max_tr is swapped
 * with the link list of the global_trace and the buffers are reset for
 * the global_trace so the tracing can continue.
 */
static struct trace_array     max_tr;

static DEFINE_PER_CPU(struct trace_array_cpu, max_data);

/* tracer_enabled is used to toggle activation of a tracer */
static int              tracer_enabled = 1;

/**
 * tracing_is_enabled - return tracer_enabled status
 *
 * This function is used by other tracers to know the status
 * of the tracer_enabled flag.  Tracers may use this function
 * to know if it should enable their features when starting
 * up. See irqsoff tracer for an example (start_irqsoff_tracer).
 */
int tracing_is_enabled(void)
{
      return tracer_enabled;
}

/*
 * trace_buf_size is the size in bytes that is allocated
 * for a buffer. Note, the number of bytes is always rounded
 * to page size.
 *
 * This number is purposely set to a low number of 16384.
 * If the dump on oops happens, it will be much appreciated
 * to not have to wait for all that output. Anyway this can be
 * boot time and run time configurable.
 */
#define TRACE_BUF_SIZE_DEFAULT      1441792UL /* 16384 * 88 (sizeof(entry)) */

static unsigned long          trace_buf_size = TRACE_BUF_SIZE_DEFAULT;

/* trace_types holds a link list of available tracers. */
static struct tracer          *trace_types __read_mostly;

/* current_trace points to the tracer that is currently active */
static struct tracer          *current_trace __read_mostly;

/*
 * max_tracer_type_len is used to simplify the allocating of
 * buffers to read userspace tracer names. We keep track of
 * the longest tracer name registered.
 */
static int              max_tracer_type_len;

/*
 * trace_types_lock is used to protect the trace_types list.
 * This lock is also used to keep user access serialized.
 * Accesses from userspace will grab this lock while userspace
 * activities happen inside the kernel.
 */
static DEFINE_MUTEX(trace_types_lock);

/* trace_wait is a waitqueue for tasks blocked on trace_poll */
static DECLARE_WAIT_QUEUE_HEAD(trace_wait);

/* trace_flags holds trace_options default values */
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
      TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
      TRACE_ITER_GRAPH_TIME;

/**
 * trace_wake_up - wake up tasks waiting for trace input
 *
 * Simply wakes up any task that is blocked on the trace_wait
 * queue. These is used with trace_poll for tasks polling the trace.
 */
void trace_wake_up(void)
{
      /*
       * The runqueue_is_locked() can fail, but this is the best we
       * have for now:
       */
      if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
            wake_up(&trace_wait);
}

static int __init set_buf_size(char *str)
{
      unsigned long buf_size;

      if (!str)
            return 0;
      buf_size = memparse(str, &str);
      /* nr_entries can not be zero */
      if (buf_size == 0)
            return 0;
      trace_buf_size = buf_size;
      return 1;
}
__setup("trace_buf_size=", set_buf_size);

unsigned long nsecs_to_usecs(unsigned long nsecs)
{
      return nsecs / 1000;
}

/* These must match the bit postions in trace_iterator_flags */
static const char *trace_options[] = {
      "print-parent",
      "sym-offset",
      "sym-addr",
      "verbose",
      "raw",
      "hex",
      "bin",
      "block",
      "stacktrace",
      "sched-tree",
      "trace_printk",
      "ftrace_preempt",
      "branch",
      "annotate",
      "userstacktrace",
      "sym-userobj",
      "printk-msg-only",
      "context-info",
      "latency-format",
      "global-clock",
      "sleep-time",
      "graph-time",
      NULL
};

/*
 * ftrace_max_lock is used to protect the swapping of buffers
 * when taking a max snapshot. The buffers themselves are
 * protected by per_cpu spinlocks. But the action of the swap
 * needs its own lock.
 *
 * This is defined as a raw_spinlock_t in order to help
 * with performance when lockdep debugging is enabled.
 */
static raw_spinlock_t ftrace_max_lock =
      (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;

/*
 * Copy the new maximum trace into the separate maximum-trace
 * structure. (this way the maximum trace is permanently saved,
 * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
 */
static void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
      struct trace_array_cpu *data = tr->data[cpu];

      max_tr.cpu = cpu;
      max_tr.time_start = data->preempt_timestamp;

      data = max_tr.data[cpu];
      data->saved_latency = tracing_max_latency;

      memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
      data->pid = tsk->pid;
      data->uid = task_uid(tsk);
      data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
      data->policy = tsk->policy;
      data->rt_priority = tsk->rt_priority;

      /* record this tasks comm */
      tracing_record_cmdline(tsk);
}

ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
      int len;
      int ret;

      if (!cnt)
            return 0;

      if (s->len <= s->readpos)
            return -EBUSY;

      len = s->len - s->readpos;
      if (cnt > len)
            cnt = len;
      ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
      if (ret == cnt)
            return -EFAULT;

      cnt -= ret;

      s->readpos += cnt;
      return cnt;
}

static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
      int len;
      void *ret;

      if (s->len <= s->readpos)
            return -EBUSY;

      len = s->len - s->readpos;
      if (cnt > len)
            cnt = len;
      ret = memcpy(buf, s->buffer + s->readpos, cnt);
      if (!ret)
            return -EFAULT;

      s->readpos += cnt;
      return cnt;
}

/**
 * update_max_tr - snapshot all trace buffers from global_trace to max_tr
 * @tr: tracer
 * @tsk: the task with the latency
 * @cpu: The cpu that initiated the trace.
 *
 * Flip the buffers between the @tr and the max_tr and record information
 * about which task was the cause of this latency.
 */
void
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
      struct ring_buffer *buf = tr->buffer;

      WARN_ON_ONCE(!irqs_disabled());
      __raw_spin_lock(&ftrace_max_lock);

      tr->buffer = max_tr.buffer;
      max_tr.buffer = buf;

      ftrace_disable_cpu();
      ring_buffer_reset(tr->buffer);
      ftrace_enable_cpu();

      __update_max_tr(tr, tsk, cpu);
      __raw_spin_unlock(&ftrace_max_lock);
}

/**
 * update_max_tr_single - only copy one trace over, and reset the rest
 * @tr - tracer
 * @tsk - task with the latency
 * @cpu - the cpu of the buffer to copy.
 *
 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
 */
void
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
      int ret;

      WARN_ON_ONCE(!irqs_disabled());
      __raw_spin_lock(&ftrace_max_lock);

      ftrace_disable_cpu();

      ring_buffer_reset(max_tr.buffer);
      ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);

      ftrace_enable_cpu();

      WARN_ON_ONCE(ret && ret != -EAGAIN);

      __update_max_tr(tr, tsk, cpu);
      __raw_spin_unlock(&ftrace_max_lock);
}

/**
 * register_tracer - register a tracer with the ftrace system.
 * @type - the plugin for the tracer
 *
 * Register a new plugin tracer.
 */
int register_tracer(struct tracer *type)
__releases(kernel_lock)
__acquires(kernel_lock)
{
      struct tracer *t;
      int len;
      int ret = 0;

      if (!type->name) {
            pr_info("Tracer must have a name\n");
            return -1;
      }

      /*
       * When this gets called we hold the BKL which means that
       * preemption is disabled. Various trace selftests however
       * need to disable and enable preemption for successful tests.
       * So we drop the BKL here and grab it after the tests again.
       */
      unlock_kernel();
      mutex_lock(&trace_types_lock);

      tracing_selftest_running = true;

      for (t = trace_types; t; t = t->next) {
            if (strcmp(type->name, t->name) == 0) {
                  /* already found */
                  pr_info("Trace %s already registered\n",
                        type->name);
                  ret = -1;
                  goto out;
            }
      }

      if (!type->set_flag)
            type->set_flag = &dummy_set_flag;
      if (!type->flags)
            type->flags = &dummy_tracer_flags;
      else
            if (!type->flags->opts)
                  type->flags->opts = dummy_tracer_opt;
      if (!type->wait_pipe)
            type->wait_pipe = default_wait_pipe;


#ifdef CONFIG_FTRACE_STARTUP_TEST
      if (type->selftest && !tracing_selftest_disabled) {
            struct tracer *saved_tracer = current_trace;
            struct trace_array *tr = &global_trace;
            int i;

            /*
             * Run a selftest on this tracer.
             * Here we reset the trace buffer, and set the current
             * tracer to be this tracer. The tracer can then run some
             * internal tracing to verify that everything is in order.
             * If we fail, we do not register this tracer.
             */
            for_each_tracing_cpu(i)
                  tracing_reset(tr, i);

            current_trace = type;
            /* the test is responsible for initializing and enabling */
            pr_info("Testing tracer %s: ", type->name);
            ret = type->selftest(type, tr);
            /* the test is responsible for resetting too */
            current_trace = saved_tracer;
            if (ret) {
                  printk(KERN_CONT "FAILED!\n");
                  goto out;
            }
            /* Only reset on passing, to avoid touching corrupted buffers */
            for_each_tracing_cpu(i)
                  tracing_reset(tr, i);

            printk(KERN_CONT "PASSED\n");
      }
#endif

      type->next = trace_types;
      trace_types = type;
      len = strlen(type->name);
      if (len > max_tracer_type_len)
            max_tracer_type_len = len;

 out:
      tracing_selftest_running = false;
      mutex_unlock(&trace_types_lock);

      if (ret || !default_bootup_tracer)
            goto out_unlock;

      if (strncmp(default_bootup_tracer, type->name, BOOTUP_TRACER_SIZE))
            goto out_unlock;

      printk(KERN_INFO "Starting tracer '%s'\n", type->name);
      /* Do we want this tracer to start on bootup? */
      tracing_set_tracer(type->name);
      default_bootup_tracer = NULL;
      /* disable other selftests, since this will break it. */
      tracing_selftest_disabled = 1;
#ifdef CONFIG_FTRACE_STARTUP_TEST
      printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
             type->name);
#endif

 out_unlock:
      lock_kernel();
      return ret;
}

void unregister_tracer(struct tracer *type)
{
      struct tracer **t;
      int len;

      mutex_lock(&trace_types_lock);
      for (t = &trace_types; *t; t = &(*t)->next) {
            if (*t == type)
                  goto found;
      }
      pr_info("Trace %s not registered\n", type->name);
      goto out;

 found:
      *t = (*t)->next;

      if (type == current_trace && tracer_enabled) {
            tracer_enabled = 0;
            tracing_stop();
            if (current_trace->stop)
                  current_trace->stop(&global_trace);
            current_trace = &nop_trace;
      }

      if (strlen(type->name) != max_tracer_type_len)
            goto out;

      max_tracer_type_len = 0;
      for (t = &trace_types; *t; t = &(*t)->next) {
            len = strlen((*t)->name);
            if (len > max_tracer_type_len)
                  max_tracer_type_len = len;
      }
 out:
      mutex_unlock(&trace_types_lock);
}

void tracing_reset(struct trace_array *tr, int cpu)
{
      ftrace_disable_cpu();
      ring_buffer_reset_cpu(tr->buffer, cpu);
      ftrace_enable_cpu();
}

void tracing_reset_online_cpus(struct trace_array *tr)
{
      int cpu;

      tr->time_start = ftrace_now(tr->cpu);

      for_each_online_cpu(cpu)
            tracing_reset(tr, cpu);
}

void tracing_reset_current(int cpu)
{
      tracing_reset(&global_trace, cpu);
}

void tracing_reset_current_online_cpus(void)
{
      tracing_reset_online_cpus(&global_trace);
}

#define SAVED_CMDLINES 128
#define NO_CMDLINE_MAP UINT_MAX
static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
static int cmdline_idx;
static raw_spinlock_t trace_cmdline_lock = __RAW_SPIN_LOCK_UNLOCKED;

/* temporary disable recording */
static atomic_t trace_record_cmdline_disabled __read_mostly;

static void trace_init_cmdlines(void)
{
      memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
      memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
      cmdline_idx = 0;
}

static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);

/**
 * ftrace_off_permanent - disable all ftrace code permanently
 *
 * This should only be called when a serious anomally has
 * been detected.  This will turn off the function tracing,
 * ring buffers, and other tracing utilites. It takes no
 * locks and can be called from any context.
 */
void ftrace_off_permanent(void)
{
      tracing_disabled = 1;
      ftrace_stop();
      tracing_off_permanent();
}

/**
 * tracing_start - quick start of the tracer
 *
 * If tracing is enabled but was stopped by tracing_stop,
 * this will start the tracer back up.
 */
void tracing_start(void)
{
      struct ring_buffer *buffer;
      unsigned long flags;

      if (tracing_disabled)
            return;

      spin_lock_irqsave(&tracing_start_lock, flags);
      if (--trace_stop_count) {
            if (trace_stop_count < 0) {
                  /* Someone screwed up their debugging */
                  WARN_ON_ONCE(1);
                  trace_stop_count = 0;
            }
            goto out;
      }


      buffer = global_trace.buffer;
      if (buffer)
            ring_buffer_record_enable(buffer);

      buffer = max_tr.buffer;
      if (buffer)
            ring_buffer_record_enable(buffer);

      ftrace_start();
 out:
      spin_unlock_irqrestore(&tracing_start_lock, flags);
}

/**
 * tracing_stop - quick stop of the tracer
 *
 * Light weight way to stop tracing. Use in conjunction with
 * tracing_start.
 */
void tracing_stop(void)
{
      struct ring_buffer *buffer;
      unsigned long flags;

      ftrace_stop();
      spin_lock_irqsave(&tracing_start_lock, flags);
      if (trace_stop_count++)
            goto out;

      buffer = global_trace.buffer;
      if (buffer)
            ring_buffer_record_disable(buffer);

      buffer = max_tr.buffer;
      if (buffer)
            ring_buffer_record_disable(buffer);

 out:
      spin_unlock_irqrestore(&tracing_start_lock, flags);
}

void trace_stop_cmdline_recording(void);

static void trace_save_cmdline(struct task_struct *tsk)
{
      unsigned pid, idx;

      if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
            return;

      /*
       * It's not the end of the world if we don't get
       * the lock, but we also don't want to spin
       * nor do we want to disable interrupts,
       * so if we miss here, then better luck next time.
       */
      if (!__raw_spin_trylock(&trace_cmdline_lock))
            return;

      idx = map_pid_to_cmdline[tsk->pid];
      if (idx == NO_CMDLINE_MAP) {
            idx = (cmdline_idx + 1) % SAVED_CMDLINES;

            /*
             * Check whether the cmdline buffer at idx has a pid
             * mapped. We are going to overwrite that entry so we
             * need to clear the map_pid_to_cmdline. Otherwise we
             * would read the new comm for the old pid.
             */
            pid = map_cmdline_to_pid[idx];
            if (pid != NO_CMDLINE_MAP)
                  map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;

            map_cmdline_to_pid[idx] = tsk->pid;
            map_pid_to_cmdline[tsk->pid] = idx;

            cmdline_idx = idx;
      }

      memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);

      __raw_spin_unlock(&trace_cmdline_lock);
}

void trace_find_cmdline(int pid, char comm[])
{
      unsigned map;

      if (!pid) {
            strcpy(comm, "<idle>");
            return;
      }

      if (pid > PID_MAX_DEFAULT) {
            strcpy(comm, "<...>");
            return;
      }

      preempt_disable();
      __raw_spin_lock(&trace_cmdline_lock);
      map = map_pid_to_cmdline[pid];
      if (map != NO_CMDLINE_MAP)
            strcpy(comm, saved_cmdlines[map]);
      else
            strcpy(comm, "<...>");

      __raw_spin_unlock(&trace_cmdline_lock);
      preempt_enable();
}

void tracing_record_cmdline(struct task_struct *tsk)
{
      if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
          !tracing_is_on())
            return;

      trace_save_cmdline(tsk);
}

void
tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
                       int pc)
{
      struct task_struct *tsk = current;

      entry->preempt_count          = pc & 0xff;
      entry->pid              = (tsk) ? tsk->pid : 0;
      entry->tgid             = (tsk) ? tsk->tgid : 0;
      entry->flags =
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
            (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
#else
            TRACE_FLAG_IRQS_NOSUPPORT |
#endif
            ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
            ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
            (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
}
EXPORT_SYMBOL_GPL(tracing_generic_entry_update);

struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
                                        int type,
                                        unsigned long len,
                                        unsigned long flags, int pc)
{
      struct ring_buffer_event *event;

      event = ring_buffer_lock_reserve(tr->buffer, len);
      if (event != NULL) {
            struct trace_entry *ent = ring_buffer_event_data(event);

            tracing_generic_entry_update(ent, flags, pc);
            ent->type = type;
      }

      return event;
}
static void ftrace_trace_stack(struct trace_array *tr,
                         unsigned long flags, int skip, int pc);
static void ftrace_trace_userstack(struct trace_array *tr,
                           unsigned long flags, int pc);

static inline void __trace_buffer_unlock_commit(struct trace_array *tr,
                              struct ring_buffer_event *event,
                              unsigned long flags, int pc,
                              int wake)
{
      ring_buffer_unlock_commit(tr->buffer, event);

      ftrace_trace_stack(tr, flags, 6, pc);
      ftrace_trace_userstack(tr, flags, pc);

      if (wake)
            trace_wake_up();
}

void trace_buffer_unlock_commit(struct trace_array *tr,
                              struct ring_buffer_event *event,
                              unsigned long flags, int pc)
{
      __trace_buffer_unlock_commit(tr, event, flags, pc, 1);
}

struct ring_buffer_event *
trace_current_buffer_lock_reserve(int type, unsigned long len,
                          unsigned long flags, int pc)
{
      return trace_buffer_lock_reserve(&global_trace,
                               type, len, flags, pc);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);

void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
                              unsigned long flags, int pc)
{
      __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 1);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);

void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
                              unsigned long flags, int pc)
{
      __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 0);
}
EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);

void trace_current_buffer_discard_commit(struct ring_buffer_event *event)
{
      ring_buffer_discard_commit(global_trace.buffer, event);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);

void
trace_function(struct trace_array *tr,
             unsigned long ip, unsigned long parent_ip, unsigned long flags,
             int pc)
{
      struct ftrace_event_call *call = &event_function;
      struct ring_buffer_event *event;
      struct ftrace_entry *entry;

      /* If we are reading the ring buffer, don't trace */
      if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
            return;

      event = trace_buffer_lock_reserve(tr, TRACE_FN, sizeof(*entry),
                                flags, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);
      entry->ip               = ip;
      entry->parent_ip        = parent_ip;

      if (!filter_check_discard(call, entry, tr->buffer, event))
            ring_buffer_unlock_commit(tr->buffer, event);
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int __trace_graph_entry(struct trace_array *tr,
                        struct ftrace_graph_ent *trace,
                        unsigned long flags,
                        int pc)
{
      struct ftrace_event_call *call = &event_funcgraph_entry;
      struct ring_buffer_event *event;
      struct ftrace_graph_ent_entry *entry;

      if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
            return 0;

      event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_ENT,
                                sizeof(*entry), flags, pc);
      if (!event)
            return 0;
      entry = ring_buffer_event_data(event);
      entry->graph_ent              = *trace;
      if (!filter_current_check_discard(call, entry, event))
            ring_buffer_unlock_commit(global_trace.buffer, event);

      return 1;
}

static void __trace_graph_return(struct trace_array *tr,
                        struct ftrace_graph_ret *trace,
                        unsigned long flags,
                        int pc)
{
      struct ftrace_event_call *call = &event_funcgraph_exit;
      struct ring_buffer_event *event;
      struct ftrace_graph_ret_entry *entry;

      if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
            return;

      event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_RET,
                                sizeof(*entry), flags, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);
      entry->ret                    = *trace;
      if (!filter_current_check_discard(call, entry, event))
            ring_buffer_unlock_commit(global_trace.buffer, event);
}
#endif

void
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
       unsigned long ip, unsigned long parent_ip, unsigned long flags,
       int pc)
{
      if (likely(!atomic_read(&data->disabled)))
            trace_function(tr, ip, parent_ip, flags, pc);
}

static void __ftrace_trace_stack(struct trace_array *tr,
                         unsigned long flags,
                         int skip, int pc)
{
#ifdef CONFIG_STACKTRACE
      struct ftrace_event_call *call = &event_kernel_stack;
      struct ring_buffer_event *event;
      struct stack_entry *entry;
      struct stack_trace trace;

      event = trace_buffer_lock_reserve(tr, TRACE_STACK,
                                sizeof(*entry), flags, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);
      memset(&entry->caller, 0, sizeof(entry->caller));

      trace.nr_entries  = 0;
      trace.max_entries = FTRACE_STACK_ENTRIES;
      trace.skip        = skip;
      trace.entries           = entry->caller;

      save_stack_trace(&trace);
      if (!filter_check_discard(call, entry, tr->buffer, event))
            ring_buffer_unlock_commit(tr->buffer, event);
#endif
}

static void ftrace_trace_stack(struct trace_array *tr,
                         unsigned long flags,
                         int skip, int pc)
{
      if (!(trace_flags & TRACE_ITER_STACKTRACE))
            return;

      __ftrace_trace_stack(tr, flags, skip, pc);
}

void __trace_stack(struct trace_array *tr,
               unsigned long flags,
               int skip, int pc)
{
      __ftrace_trace_stack(tr, flags, skip, pc);
}

static void ftrace_trace_userstack(struct trace_array *tr,
                           unsigned long flags, int pc)
{
#ifdef CONFIG_STACKTRACE
      struct ftrace_event_call *call = &event_user_stack;
      struct ring_buffer_event *event;
      struct userstack_entry *entry;
      struct stack_trace trace;

      if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
            return;

      event = trace_buffer_lock_reserve(tr, TRACE_USER_STACK,
                                sizeof(*entry), flags, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);

      memset(&entry->caller, 0, sizeof(entry->caller));

      trace.nr_entries  = 0;
      trace.max_entries = FTRACE_STACK_ENTRIES;
      trace.skip        = 0;
      trace.entries           = entry->caller;

      save_stack_trace_user(&trace);
      if (!filter_check_discard(call, entry, tr->buffer, event))
            ring_buffer_unlock_commit(tr->buffer, event);
#endif
}

#ifdef UNUSED
static void __trace_userstack(struct trace_array *tr, unsigned long flags)
{
      ftrace_trace_userstack(tr, flags, preempt_count());
}
#endif /* UNUSED */

static void
ftrace_trace_special(void *__tr,
                 unsigned long arg1, unsigned long arg2, unsigned long arg3,
                 int pc)
{
      struct ring_buffer_event *event;
      struct trace_array *tr = __tr;
      struct special_entry *entry;

      event = trace_buffer_lock_reserve(tr, TRACE_SPECIAL,
                                sizeof(*entry), 0, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);
      entry->arg1             = arg1;
      entry->arg2             = arg2;
      entry->arg3             = arg3;
      trace_buffer_unlock_commit(tr, event, 0, pc);
}

void
__trace_special(void *__tr, void *__data,
            unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
      ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
}

void
tracing_sched_switch_trace(struct trace_array *tr,
                     struct task_struct *prev,
                     struct task_struct *next,
                     unsigned long flags, int pc)
{
      struct ftrace_event_call *call = &event_context_switch;
      struct ring_buffer_event *event;
      struct ctx_switch_entry *entry;

      event = trace_buffer_lock_reserve(tr, TRACE_CTX,
                                sizeof(*entry), flags, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);
      entry->prev_pid               = prev->pid;
      entry->prev_prio        = prev->prio;
      entry->prev_state       = prev->state;
      entry->next_pid               = next->pid;
      entry->next_prio        = next->prio;
      entry->next_state       = next->state;
      entry->next_cpu   = task_cpu(next);

      if (!filter_check_discard(call, entry, tr->buffer, event))
            trace_buffer_unlock_commit(tr, event, flags, pc);
}

void
tracing_sched_wakeup_trace(struct trace_array *tr,
                     struct task_struct *wakee,
                     struct task_struct *curr,
                     unsigned long flags, int pc)
{
      struct ftrace_event_call *call = &event_wakeup;
      struct ring_buffer_event *event;
      struct ctx_switch_entry *entry;

      event = trace_buffer_lock_reserve(tr, TRACE_WAKE,
                                sizeof(*entry), flags, pc);
      if (!event)
            return;
      entry = ring_buffer_event_data(event);
      entry->prev_pid               = curr->pid;
      entry->prev_prio        = curr->prio;
      entry->prev_state       = curr->state;
      entry->next_pid               = wakee->pid;
      entry->next_prio        = wakee->prio;
      entry->next_state       = wakee->state;
      entry->next_cpu               = task_cpu(wakee);

      if (!filter_check_discard(call, entry, tr->buffer, event))
            ring_buffer_unlock_commit(tr->buffer, event);
      ftrace_trace_stack(tr, flags, 6, pc);
      ftrace_trace_userstack(tr, flags, pc);
}

void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
      struct trace_array *tr = &global_trace;
      struct trace_array_cpu *data;
      unsigned long flags;
      int cpu;
      int pc;

      if (tracing_disabled)
            return;

      pc = preempt_count();
      local_irq_save(flags);
      cpu = raw_smp_processor_id();
      data = tr->data[cpu];

      if (likely(atomic_inc_return(&data->disabled) == 1))
            ftrace_trace_special(tr, arg1, arg2, arg3, pc);

      atomic_dec(&data->disabled);
      local_irq_restore(flags);
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
int trace_graph_entry(struct ftrace_graph_ent *trace)
{
      struct trace_array *tr = &global_trace;
      struct trace_array_cpu *data;
      unsigned long flags;
      long disabled;
      int ret;
      int cpu;
      int pc;

      if (!ftrace_trace_task(current))
            return 0;

      if (!ftrace_graph_addr(trace->func))
            return 0;

      local_irq_save(flags);
      cpu = raw_smp_processor_id();
      data = tr->data[cpu];
      disabled = atomic_inc_return(&data->disabled);
      if (likely(disabled == 1)) {
            pc = preempt_count();
            ret = __trace_graph_entry(tr, trace, flags, pc);
      } else {
            ret = 0;
      }
      /* Only do the atomic if it is not already set */
      if (!test_tsk_trace_graph(current))
            set_tsk_trace_graph(current);

      atomic_dec(&data->disabled);
      local_irq_restore(flags);

      return ret;
}

void trace_graph_return(struct ftrace_graph_ret *trace)
{
      struct trace_array *tr = &global_trace;
      struct trace_array_cpu *data;
      unsigned long flags;
      long disabled;
      int cpu;
      int pc;

      local_irq_save(flags);
      cpu = raw_smp_processor_id();
      data = tr->data[cpu];
      disabled = atomic_inc_return(&data->disabled);
      if (likely(disabled == 1)) {
            pc = preempt_count();
            __trace_graph_return(tr, trace, flags, pc);
      }
      if (!trace->depth)
            clear_tsk_trace_graph(current);
      atomic_dec(&data->disabled);
      local_irq_restore(flags);
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */


/**
 * trace_vbprintk - write binary msg to tracing buffer
 *
 */
int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
{
      static raw_spinlock_t trace_buf_lock =
            (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
      static u32 trace_buf[TRACE_BUF_SIZE];

      struct ftrace_event_call *call = &event_bprint;
      struct ring_buffer_event *event;
      struct trace_array *tr = &global_trace;
      struct trace_array_cpu *data;
      struct bprint_entry *entry;
      unsigned long flags;
      int disable;
      int resched;
      int cpu, len = 0, size, pc;

      if (unlikely(tracing_selftest_running || tracing_disabled))
            return 0;

      /* Don't pollute graph traces with trace_vprintk internals */
      pause_graph_tracing();

      pc = preempt_count();
      resched = ftrace_preempt_disable();
      cpu = raw_smp_processor_id();
      data = tr->data[cpu];

      disable = atomic_inc_return(&data->disabled);
      if (unlikely(disable != 1))
            goto out;

      /* Lockdep uses trace_printk for lock tracing */
      local_irq_save(flags);
      __raw_spin_lock(&trace_buf_lock);
      len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);

      if (len > TRACE_BUF_SIZE || len < 0)
            goto out_unlock;

      size = sizeof(*entry) + sizeof(u32) * len;
      event = trace_buffer_lock_reserve(tr, TRACE_BPRINT, size, flags, pc);
      if (!event)
            goto out_unlock;
      entry = ring_buffer_event_data(event);
      entry->ip               = ip;
      entry->fmt              = fmt;

      memcpy(entry->buf, trace_buf, sizeof(u32) * len);
      if (!filter_check_discard(call, entry, tr->buffer, event))
            ring_buffer_unlock_commit(tr->buffer, event);

out_unlock:
      __raw_spin_unlock(&trace_buf_lock);
      local_irq_restore(flags);

out:
      atomic_dec_return(&data->disabled);
      ftrace_preempt_enable(resched);
      unpause_graph_tracing();

      return len;
}
EXPORT_SYMBOL_GPL(trace_vbprintk);

int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
{
      static raw_spinlock_t trace_buf_lock = __RAW_SPIN_LOCK_UNLOCKED;
      static char trace_buf[TRACE_BUF_SIZE];

      struct ftrace_event_call *call = &event_print;
      struct ring_buffer_event *event;
      struct trace_array *tr = &global_trace;
      struct trace_array_cpu *data;
      int cpu, len = 0, size, pc;
      struct print_entry *entry;
      unsigned long irq_flags;
      int disable;

      if (tracing_disabled || tracing_selftest_running)
            return 0;

      pc = preempt_count();
      preempt_disable_notrace();
      cpu = raw_smp_processor_id();
      data = tr->data[cpu];

      disable = atomic_inc_return(&data->disabled);
      if (unlikely(disable != 1))
            goto out;

      pause_graph_tracing();
      raw_local_irq_save(irq_flags);
      __raw_spin_lock(&trace_buf_lock);
      len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);

      len = min(len, TRACE_BUF_SIZE-1);
      trace_buf[len] = 0;

      size = sizeof(*entry) + len + 1;
      event = trace_buffer_lock_reserve(tr, TRACE_PRINT, size, irq_flags, pc);
      if (!event)
            goto out_unlock;
      entry = ring_buffer_event_data(event);
      entry->ip               = ip;

      memcpy(&entry->buf, trace_buf, len);
      entry->buf[len] = 0;
      if (!filter_check_discard(call, entry, tr->buffer, event))
            ring_buffer_unlock_commit(tr->buffer, event);

 out_unlock:
      __raw_spin_unlock(&trace_buf_lock);
      raw_local_irq_restore(irq_flags);
      unpause_graph_tracing();
 out:
      atomic_dec_return(&data->disabled);
      preempt_enable_notrace();

      return len;
}
EXPORT_SYMBOL_GPL(trace_vprintk);

enum trace_file_type {
      TRACE_FILE_LAT_FMT      = 1,
      TRACE_FILE_ANNOTATE     = 2,
};

static void trace_iterator_increment(struct trace_iterator *iter)
{
      /* Don't allow ftrace to trace into the ring buffers */
      ftrace_disable_cpu();

      iter->idx++;
      if (iter->buffer_iter[iter->cpu])
            ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);

      ftrace_enable_cpu();
}

static struct trace_entry *
peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts)
{
      struct ring_buffer_event *event;
      struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];

      /* Don't allow ftrace to trace into the ring buffers */
      ftrace_disable_cpu();

      if (buf_iter)
            event = ring_buffer_iter_peek(buf_iter, ts);
      else
            event = ring_buffer_peek(iter->tr->buffer, cpu, ts);

      ftrace_enable_cpu();

      return event ? ring_buffer_event_data(event) : NULL;
}

static struct trace_entry *
__find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
{
      struct ring_buffer *buffer = iter->tr->buffer;
      struct trace_entry *ent, *next = NULL;
      int cpu_file = iter->cpu_file;
      u64 next_ts = 0, ts;
      int next_cpu = -1;
      int cpu;

      /*
       * If we are in a per_cpu trace file, don't bother by iterating over
       * all cpu and peek directly.
       */
      if (cpu_file > TRACE_PIPE_ALL_CPU) {
            if (ring_buffer_empty_cpu(buffer, cpu_file))
                  return NULL;
            ent = peek_next_entry(iter, cpu_file, ent_ts);
            if (ent_cpu)
                  *ent_cpu = cpu_file;

            return ent;
      }

      for_each_tracing_cpu(cpu) {

            if (ring_buffer_empty_cpu(buffer, cpu))
                  continue;

            ent = peek_next_entry(iter, cpu, &ts);

            /*
             * Pick the entry with the smallest timestamp:
             */
            if (ent && (!next || ts < next_ts)) {
                  next = ent;
                  next_cpu = cpu;
                  next_ts = ts;
            }
      }

      if (ent_cpu)
            *ent_cpu = next_cpu;

      if (ent_ts)
            *ent_ts = next_ts;

      return next;
}

/* Find the next real entry, without updating the iterator itself */
struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
                                int *ent_cpu, u64 *ent_ts)
{
      return __find_next_entry(iter, ent_cpu, ent_ts);
}

/* Find the next real entry, and increment the iterator to the next entry */
static void *find_next_entry_inc(struct trace_iterator *iter)
{
      iter->ent = __find_next_entry(iter, &iter->cpu, &iter->ts);

      if (iter->ent)
            trace_iterator_increment(iter);

      return iter->ent ? iter : NULL;
}

static void trace_consume(struct trace_iterator *iter)
{
      /* Don't allow ftrace to trace into the ring buffers */
      ftrace_disable_cpu();
      ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts);
      ftrace_enable_cpu();
}

static void *s_next(struct seq_file *m, void *v, loff_t *pos)
{
      struct trace_iterator *iter = m->private;
      int i = (int)*pos;
      void *ent;

      (*pos)++;

      /* can't go backwards */
      if (iter->idx > i)
            return NULL;

      if (iter->idx < 0)
            ent = find_next_entry_inc(iter);
      else
            ent = iter;

      while (ent && iter->idx < i)
            ent = find_next_entry_inc(iter);

      iter->pos = *pos;

      return ent;
}

/*
 * No necessary locking here. The worst thing which can
 * happen is loosing events consumed at the same time
 * by a trace_pipe reader.
 * Other than that, we don't risk to crash the ring buffer
 * because it serializes the readers.
 *
 * The current tracer is copied to avoid a global locking
 * all around.
 */
static void *s_start(struct seq_file *m, loff_t *pos)
{
      struct trace_iterator *iter = m->private;
      static struct tracer *old_tracer;
      int cpu_file = iter->cpu_file;
      void *p = NULL;
      loff_t l = 0;
      int cpu;

      /* copy the tracer to avoid using a global lock all around */
      mutex_lock(&trace_types_lock);
      if (unlikely(old_tracer != current_trace && current_trace)) {
            old_tracer = current_trace;
            *iter->trace = *current_trace;
      }
      mutex_unlock(&trace_types_lock);

      atomic_inc(&trace_record_cmdline_disabled);

      if (*pos != iter->pos) {
            iter->ent = NULL;
            iter->cpu = 0;
            iter->idx = -1;

            ftrace_disable_cpu();

            if (cpu_file == TRACE_PIPE_ALL_CPU) {
                  for_each_tracing_cpu(cpu)
                        ring_buffer_iter_reset(iter->buffer_iter[cpu]);
            } else
                  ring_buffer_iter_reset(iter->buffer_iter[cpu_file]);


            ftrace_enable_cpu();

            for (p = iter; p && l < *pos; p = s_next(m, p, &l))
                  ;

      } else {
            l = *pos - 1;
            p = s_next(m, p, &l);
      }

      trace_event_read_lock();
      return p;
}

static void s_stop(struct seq_file *m, void *p)
{
      atomic_dec(&trace_record_cmdline_disabled);
      trace_event_read_unlock();
}

static void print_lat_help_header(struct seq_file *m)
{
      seq_puts(m, "#                  _------=> CPU#            \n");
      seq_puts(m, "#                 / _-----=> irqs-off        \n");
      seq_puts(m, "#                | / _----=> need-resched    \n");
      seq_puts(m, "#                || / _---=> hardirq/softirq \n");
      seq_puts(m, "#                ||| / _--=> preempt-depth   \n");
      seq_puts(m, "#                |||| /                      \n");
      seq_puts(m, "#                |||||     delay             \n");
      seq_puts(m, "#  cmd     pid   ||||| time  |   caller      \n");
      seq_puts(m, "#     \\   /      |||||   \\   |   /           \n");
}

static void print_func_help_header(struct seq_file *m)
{
      seq_puts(m, "#           TASK-PID    CPU#    TIMESTAMP  FUNCTION\n");
      seq_puts(m, "#              | |       |          |         |\n");
}


static void
print_trace_header(struct seq_file *m, struct trace_iterator *iter)
{
      unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
      struct trace_array *tr = iter->tr;
      struct trace_array_cpu *data = tr->data[tr->cpu];
      struct tracer *type = current_trace;
      unsigned long total;
      unsigned long entries;
      const char *name = "preemption";

      if (type)
            name = type->name;

      entries = ring_buffer_entries(iter->tr->buffer);
      total = entries +
            ring_buffer_overruns(iter->tr->buffer);

      seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
               name, UTS_RELEASE);
      seq_puts(m, "# -----------------------------------"
             "---------------------------------\n");
      seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
               " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
               nsecs_to_usecs(data->saved_latency),
               entries,
               total,
               tr->cpu,
#if defined(CONFIG_PREEMPT_NONE)
               "server",
#elif defined(CONFIG_PREEMPT_VOLUNTARY)
               "desktop",
#elif defined(CONFIG_PREEMPT)
               "preempt",
#else
               "unknown",
#endif
               /* These are reserved for later use */
               0, 0, 0, 0);
#ifdef CONFIG_SMP
      seq_printf(m, " #P:%d)\n", num_online_cpus());
#else
      seq_puts(m, ")\n");
#endif
      seq_puts(m, "#    -----------------\n");
      seq_printf(m, "#    | task: %.16s-%d "
               "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
               data->comm, data->pid, data->uid, data->nice,
               data->policy, data->rt_priority);
      seq_puts(m, "#    -----------------\n");

      if (data->critical_start) {
            seq_puts(m, "#  => started at: ");
            seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
            trace_print_seq(m, &iter->seq);
            seq_puts(m, "\n#  => ended at:   ");
            seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
            trace_print_seq(m, &iter->seq);
            seq_puts(m, "#\n");
      }

      seq_puts(m, "#\n");
}

static void test_cpu_buff_start(struct trace_iterator *iter)
{
      struct trace_seq *s = &iter->seq;

      if (!(trace_flags & TRACE_ITER_ANNOTATE))
            return;

      if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
            return;

      if (cpumask_test_cpu(iter->cpu, iter->started))
            return;

      cpumask_set_cpu(iter->cpu, iter->started);

      /* Don't print started cpu buffer for the first entry of the trace */
      if (iter->idx > 1)
            trace_seq_printf(s, "##### CPU %u buffer started ####\n",
                        iter->cpu);
}

static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
{
      struct trace_seq *s = &iter->seq;
      unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
      struct trace_entry *entry;
      struct trace_event *event;

      entry = iter->ent;

      test_cpu_buff_start(iter);

      event = ftrace_find_event(entry->type);

      if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
            if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
                  if (!trace_print_lat_context(iter))
                        goto partial;
            } else {
                  if (!trace_print_context(iter))
                        goto partial;
            }
      }

      if (event)
            return event->trace(iter, sym_flags);

      if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
            goto partial;

      return TRACE_TYPE_HANDLED;
partial:
      return TRACE_TYPE_PARTIAL_LINE;
}

static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
{
      struct trace_seq *s = &iter->seq;
      struct trace_entry *entry;
      struct trace_event *event;

      entry = iter->ent;

      if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
            if (!trace_seq_printf(s, "%d %d %llu ",
                              entry->pid, iter->cpu, iter->ts))
                  goto partial;
      }

      event = ftrace_find_event(entry->type);
      if (event)
            return event->raw(iter, 0);

      if (!trace_seq_printf(s, "%d ?\n", entry->type))
            goto partial;

      return TRACE_TYPE_HANDLED;
partial:
      return TRACE_TYPE_PARTIAL_LINE;
}

static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
{
      struct trace_seq *s = &iter->seq;
      unsigned char newline = '\n';
      struct trace_entry *entry;
      struct trace_event *event;

      entry = iter->ent;

      if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
            SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
            SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
            SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
      }

      event = ftrace_find_event(entry->type);
      if (event) {
            enum print_line_t ret = event->hex(iter, 0);
            if (ret != TRACE_TYPE_HANDLED)
                  return ret;
      }

      SEQ_PUT_FIELD_RET(s, newline);

      return TRACE_TYPE_HANDLED;
}

static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
{
      struct trace_seq *s = &iter->seq;
      struct trace_entry *entry;
      struct trace_event *event;

      entry = iter->ent;

      if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
            SEQ_PUT_FIELD_RET(s, entry->pid);
            SEQ_PUT_FIELD_RET(s, iter->cpu);
            SEQ_PUT_FIELD_RET(s, iter->ts);
      }

      event = ftrace_find_event(entry->type);
      return event ? event->binary(iter, 0) : TRACE_TYPE_HANDLED;
}

static int trace_empty(struct trace_iterator *iter)
{
      int cpu;

      /* If we are looking at one CPU buffer, only check that one */
      if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
            cpu = iter->cpu_file;
            if (iter->buffer_iter[cpu]) {
                  if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
                        return 0;
            } else {
                  if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
                        return 0;
            }
            return 1;
      }

      for_each_tracing_cpu(cpu) {
            if (iter->buffer_iter[cpu]) {
                  if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
                        return 0;
            } else {
                  if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
                        return 0;
            }
      }

      return 1;
}

/*  Called with trace_event_read_lock() held. */
static enum print_line_t print_trace_line(struct trace_iterator *iter)
{
      enum print_line_t ret;

      if (iter->trace && iter->trace->print_line) {
            ret = iter->trace->print_line(iter);
            if (ret != TRACE_TYPE_UNHANDLED)
                  return ret;
      }

      if (iter->ent->type == TRACE_BPRINT &&
                  trace_flags & TRACE_ITER_PRINTK &&
                  trace_flags & TRACE_ITER_PRINTK_MSGONLY)
            return trace_print_bprintk_msg_only(iter);

      if (iter->ent->type == TRACE_PRINT &&
                  trace_flags & TRACE_ITER_PRINTK &&
                  trace_flags & TRACE_ITER_PRINTK_MSGONLY)
            return trace_print_printk_msg_only(iter);

      if (trace_flags & TRACE_ITER_BIN)
            return print_bin_fmt(iter);

      if (trace_flags & TRACE_ITER_HEX)
            return print_hex_fmt(iter);

      if (trace_flags & TRACE_ITER_RAW)
            return print_raw_fmt(iter);

      return print_trace_fmt(iter);
}

static int s_show(struct seq_file *m, void *v)
{
      struct trace_iterator *iter = v;

      if (iter->ent == NULL) {
            if (iter->tr) {
                  seq_printf(m, "# tracer: %s\n", iter->trace->name);
                  seq_puts(m, "#\n");
            }
            if (iter->trace && iter->trace->print_header)
                  iter->trace->print_header(m);
            else if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
                  /* print nothing if the buffers are empty */
                  if (trace_empty(iter))
                        return 0;
                  print_trace_header(m, iter);
                  if (!(trace_flags & TRACE_ITER_VERBOSE))
                        print_lat_help_header(m);
            } else {
                  if (!(trace_flags & TRACE_ITER_VERBOSE))
                        print_func_help_header(m);
            }
      } else {
            print_trace_line(iter);
            trace_print_seq(m, &iter->seq);
      }

      return 0;
}

static struct seq_operations tracer_seq_ops = {
      .start            = s_start,
      .next       = s_next,
      .stop       = s_stop,
      .show       = s_show,
};

static struct trace_iterator *
__tracing_open(struct inode *inode, struct file *file)
{
      long cpu_file = (long) inode->i_private;
      void *fail_ret = ERR_PTR(-ENOMEM);
      struct trace_iterator *iter;
      struct seq_file *m;
      int cpu, ret;

      if (tracing_disabled)
            return ERR_PTR(-ENODEV);

      iter = kzalloc(sizeof(*iter), GFP_KERNEL);
      if (!iter)
            return ERR_PTR(-ENOMEM);

      /*
       * We make a copy of the current tracer to avoid concurrent
       * changes on it while we are reading.
       */
      mutex_lock(&trace_types_lock);
      iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
      if (!iter->trace)
            goto fail;

      if (current_trace)
            *iter->trace = *current_trace;

      if (!alloc_cpumask_var(&iter->started, GFP_KERNEL))
            goto fail;

      cpumask_clear(iter->started);

      if (current_trace && current_trace->print_max)
            iter->tr = &max_tr;
      else
            iter->tr = &global_trace;
      iter->pos = -1;
      mutex_init(&iter->mutex);
      iter->cpu_file = cpu_file;

      /* Notify the tracer early; before we stop tracing. */
      if (iter->trace && iter->trace->open)
            iter->trace->open(iter);

      /* Annotate start of buffers if we had overruns */
      if (ring_buffer_overruns(iter->tr->buffer))
            iter->iter_flags |= TRACE_FILE_ANNOTATE;

      if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
            for_each_tracing_cpu(cpu) {

                  iter->buffer_iter[cpu] =
                        ring_buffer_read_start(iter->tr->buffer, cpu);
            }
      } else {
            cpu = iter->cpu_file;
            iter->buffer_iter[cpu] =
                        ring_buffer_read_start(iter->tr->buffer, cpu);
      }

      /* TODO stop tracer */
      ret = seq_open(file, &tracer_seq_ops);
      if (ret < 0) {
            fail_ret = ERR_PTR(ret);
            goto fail_buffer;
      }

      m = file->private_data;
      m->private = iter;

      /* stop the trace while dumping */
      tracing_stop();

      mutex_unlock(&trace_types_lock);

      return iter;

 fail_buffer:
      for_each_tracing_cpu(cpu) {
            if (iter->buffer_iter[cpu])
                  ring_buffer_read_finish(iter->buffer_iter[cpu]);
      }
      free_cpumask_var(iter->started);
 fail:
      mutex_unlock(&trace_types_lock);
      kfree(iter->trace);
      kfree(iter);

      return fail_ret;
}

int tracing_open_generic(struct inode *inode, struct file *filp)
{
      if (tracing_disabled)
            return -ENODEV;

      filp->private_data = inode->i_private;
      return 0;
}

static int tracing_release(struct inode *inode, struct file *file)
{
      struct seq_file *m = (struct seq_file *)file->private_data;
      struct trace_iterator *iter;
      int cpu;

      if (!(file->f_mode & FMODE_READ))
            return 0;

      iter = m->private;

      mutex_lock(&trace_types_lock);
      for_each_tracing_cpu(cpu) {
            if (iter->buffer_iter[cpu])
                  ring_buffer_read_finish(iter->buffer_iter[cpu]);
      }

      if (iter->trace && iter->trace->close)
            iter->trace->close(iter);

      /* reenable tracing if it was previously enabled */
      tracing_start();
      mutex_unlock(&trace_types_lock);

      seq_release(inode, file);
      mutex_destroy(&iter->mutex);
      free_cpumask_var(iter->started);
      kfree(iter->trace);
      kfree(iter);
      return 0;
}

static int tracing_open(struct inode *inode, struct file *file)
{
      struct trace_iterator *iter;
      int ret = 0;

      /* If this file was open for write, then erase contents */
      if ((file->f_mode & FMODE_WRITE) &&
          (file->f_flags & O_TRUNC)) {
            long cpu = (long) inode->i_private;

            if (cpu == TRACE_PIPE_ALL_CPU)
                  tracing_reset_online_cpus(&global_trace);
            else
                  tracing_reset(&global_trace, cpu);
      }

      if (file->f_mode & FMODE_READ) {
            iter = __tracing_open(inode, file);
            if (IS_ERR(iter))
                  ret = PTR_ERR(iter);
            else if (trace_flags & TRACE_ITER_LATENCY_FMT)
                  iter->iter_flags |= TRACE_FILE_LAT_FMT;
      }
      return ret;
}

static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
      struct tracer *t = v;

      (*pos)++;

      if (t)
            t = t->next;

      return t;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
      struct tracer *t;
      loff_t l = 0;

      mutex_lock(&trace_types_lock);
      for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
            ;

      return t;
}

static void t_stop(struct seq_file *m, void *p)
{
      mutex_unlock(&trace_types_lock);
}

static int t_show(struct seq_file *m, void *v)
{
      struct tracer *t = v;

      if (!t)
            return 0;

      seq_printf(m, "%s", t->name);
      if (t->next)
            seq_putc(m, ' ');
      else
            seq_putc(m, '\n');

      return 0;
}

static struct seq_operations show_traces_seq_ops = {
      .start            = t_start,
      .next       = t_next,
      .stop       = t_stop,
      .show       = t_show,
};

static int show_traces_open(struct inode *inode, struct file *file)
{
      if (tracing_disabled)
            return -ENODEV;

      return seq_open(file, &show_traces_seq_ops);
}

static ssize_t
tracing_write_stub(struct file *filp, const char __user *ubuf,
               size_t count, loff_t *ppos)
{
      return count;
}

static const struct file_operations tracing_fops = {
      .open       = tracing_open,
      .read       = seq_read,
      .write            = tracing_write_stub,
      .llseek           = seq_lseek,
      .release    = tracing_release,
};

static const struct file_operations show_traces_fops = {
      .open       = show_traces_open,
      .read       = seq_read,
      .release    = seq_release,
};

/*
 * Only trace on a CPU if the bitmask is set:
 */
static cpumask_var_t tracing_cpumask;

/*
 * The tracer itself will not take this lock, but still we want
 * to provide a consistent cpumask to user-space:
 */
static DEFINE_MUTEX(tracing_cpumask_update_lock);

/*
 * Temporary storage for the character representation of the
 * CPU bitmask (and one more byte for the newline):
 */
static char mask_str[NR_CPUS + 1];

static ssize_t
tracing_cpumask_read(struct file *filp, char __user *ubuf,
                 size_t count, loff_t *ppos)
{
      int len;

      mutex_lock(&tracing_cpumask_update_lock);

      len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
      if (count - len < 2) {
            count = -EINVAL;
            goto out_err;
      }
      len += sprintf(mask_str + len, "\n");
      count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);

out_err:
      mutex_unlock(&tracing_cpumask_update_lock);

      return count;
}

static ssize_t
tracing_cpumask_write(struct file *filp, const char __user *ubuf,
                  size_t count, loff_t *ppos)
{
      int err, cpu;
      cpumask_var_t tracing_cpumask_new;

      if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
            return -ENOMEM;

      err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
      if (err)
            goto err_unlock;

      mutex_lock(&tracing_cpumask_update_lock);

      local_irq_disable();
      __raw_spin_lock(&ftrace_max_lock);
      for_each_tracing_cpu(cpu) {
            /*
             * Increase/decrease the disabled counter if we are
             * about to flip a bit in the cpumask:
             */
            if (cpumask_test_cpu(cpu, tracing_cpumask) &&
                        !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
                  atomic_inc(&global_trace.data[cpu]->disabled);
            }
            if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
                        cpumask_test_cpu(cpu, tracing_cpumask_new)) {
                  atomic_dec(&global_trace.data[cpu]->disabled);
            }
      }
      __raw_spin_unlock(&ftrace_max_lock);
      local_irq_enable();

      cpumask_copy(tracing_cpumask, tracing_cpumask_new);

      mutex_unlock(&tracing_cpumask_update_lock);
      free_cpumask_var(tracing_cpumask_new);

      return count;

err_unlock:
      free_cpumask_var(tracing_cpumask_new);

      return err;
}

static const struct file_operations tracing_cpumask_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_cpumask_read,
      .write            = tracing_cpumask_write,
};

static ssize_t
tracing_trace_options_read(struct file *filp, char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
      struct tracer_opt *trace_opts;
      u32 tracer_flags;
      int len = 0;
      char *buf;
      int r = 0;
      int i;


      /* calculate max size */
      for (i = 0; trace_options[i]; i++) {
            len += strlen(trace_options[i]);
            len += 3; /* "no" and newline */
      }

      mutex_lock(&trace_types_lock);
      tracer_flags = current_trace->flags->val;
      trace_opts = current_trace->flags->opts;

      /*
       * Increase the size with names of options specific
       * of the current tracer.
       */
      for (i = 0; trace_opts[i].name; i++) {
            len += strlen(trace_opts[i].name);
            len += 3; /* "no" and newline */
      }

      /* +2 for \n and \0 */
      buf = kmalloc(len + 2, GFP_KERNEL);
      if (!buf) {
            mutex_unlock(&trace_types_lock);
            return -ENOMEM;
      }

      for (i = 0; trace_options[i]; i++) {
            if (trace_flags & (1 << i))
                  r += sprintf(buf + r, "%s\n", trace_options[i]);
            else
                  r += sprintf(buf + r, "no%s\n", trace_options[i]);
      }

      for (i = 0; trace_opts[i].name; i++) {
            if (tracer_flags & trace_opts[i].bit)
                  r += sprintf(buf + r, "%s\n",
                        trace_opts[i].name);
            else
                  r += sprintf(buf + r, "no%s\n",
                        trace_opts[i].name);
      }
      mutex_unlock(&trace_types_lock);

      WARN_ON(r >= len + 2);

      r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);

      kfree(buf);
      return r;
}

/* Try to assign a tracer specific option */
static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
{
      struct tracer_flags *trace_flags = trace->flags;
      struct tracer_opt *opts = NULL;
      int ret = 0, i = 0;
      int len;

      for (i = 0; trace_flags->opts[i].name; i++) {
            opts = &trace_flags->opts[i];
            len = strlen(opts->name);

            if (strncmp(cmp, opts->name, len) == 0) {
                  ret = trace->set_flag(trace_flags->val,
                        opts->bit, !neg);
                  break;
            }
      }
      /* Not found */
      if (!trace_flags->opts[i].name)
            return -EINVAL;

      /* Refused to handle */
      if (ret)
            return ret;

      if (neg)
            trace_flags->val &= ~opts->bit;
      else
            trace_flags->val |= opts->bit;

      return 0;
}

static void set_tracer_flags(unsigned int mask, int enabled)
{
      /* do nothing if flag is already set */
      if (!!(trace_flags & mask) == !!enabled)
            return;

      if (enabled)
            trace_flags |= mask;
      else
            trace_flags &= ~mask;

      if (mask == TRACE_ITER_GLOBAL_CLK) {
            u64 (*func)(void);

            if (enabled)
                  func = trace_clock_global;
            else
                  func = trace_clock_local;

            mutex_lock(&trace_types_lock);
            ring_buffer_set_clock(global_trace.buffer, func);

            if (max_tr.buffer)
                  ring_buffer_set_clock(max_tr.buffer, func);
            mutex_unlock(&trace_types_lock);
      }
}

static ssize_t
tracing_trace_options_write(struct file *filp, const char __user *ubuf,
                  size_t cnt, loff_t *ppos)
{
      char buf[64];
      char *cmp = buf;
      int neg = 0;
      int ret;
      int i;

      if (cnt >= sizeof(buf))
            return -EINVAL;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      if (strncmp(buf, "no", 2) == 0) {
            neg = 1;
            cmp += 2;
      }

      for (i = 0; trace_options[i]; i++) {
            int len = strlen(trace_options[i]);

            if (strncmp(cmp, trace_options[i], len) == 0) {
                  set_tracer_flags(1 << i, !neg);
                  break;
            }
      }

      /* If no option could be set, test the specific tracer options */
      if (!trace_options[i]) {
            mutex_lock(&trace_types_lock);
            ret = set_tracer_option(current_trace, cmp, neg);
            mutex_unlock(&trace_types_lock);
            if (ret)
                  return ret;
      }

      filp->f_pos += cnt;

      return cnt;
}

static const struct file_operations tracing_iter_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_trace_options_read,
      .write            = tracing_trace_options_write,
};

static const char readme_msg[] =
      "tracing mini-HOWTO:\n\n"
      "# mount -t debugfs nodev /sys/kernel/debug\n\n"
      "# cat /sys/kernel/debug/tracing/available_tracers\n"
      "wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
      "# cat /sys/kernel/debug/tracing/current_tracer\n"
      "nop\n"
      "# echo sched_switch > /sys/kernel/debug/tracing/current_tracer\n"
      "# cat /sys/kernel/debug/tracing/current_tracer\n"
      "sched_switch\n"
      "# cat /sys/kernel/debug/tracing/trace_options\n"
      "noprint-parent nosym-offset nosym-addr noverbose\n"
      "# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
      "# echo 1 > /sys/kernel/debug/tracing/tracing_enabled\n"
      "# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
      "# echo 0 > /sys/kernel/debug/tracing/tracing_enabled\n"
;

static ssize_t
tracing_readme_read(struct file *filp, char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
      return simple_read_from_buffer(ubuf, cnt, ppos,
                              readme_msg, strlen(readme_msg));
}

static const struct file_operations tracing_readme_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_readme_read,
};

static ssize_t
tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
                        size_t cnt, loff_t *ppos)
{
      char *buf_comm;
      char *file_buf;
      char *buf;
      int len = 0;
      int pid;
      int i;

      file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
      if (!file_buf)
            return -ENOMEM;

      buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
      if (!buf_comm) {
            kfree(file_buf);
            return -ENOMEM;
      }

      buf = file_buf;

      for (i = 0; i < SAVED_CMDLINES; i++) {
            int r;

            pid = map_cmdline_to_pid[i];
            if (pid == -1 || pid == NO_CMDLINE_MAP)
                  continue;

            trace_find_cmdline(pid, buf_comm);
            r = sprintf(buf, "%d %s\n", pid, buf_comm);
            buf += r;
            len += r;
      }

      len = simple_read_from_buffer(ubuf, cnt, ppos,
                              file_buf, len);

      kfree(file_buf);
      kfree(buf_comm);

      return len;
}

static const struct file_operations tracing_saved_cmdlines_fops = {
    .open       = tracing_open_generic,
    .read       = tracing_saved_cmdlines_read,
};

static ssize_t
tracing_ctrl_read(struct file *filp, char __user *ubuf,
              size_t cnt, loff_t *ppos)
{
      char buf[64];
      int r;

      r = sprintf(buf, "%u\n", tracer_enabled);
      return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static ssize_t
tracing_ctrl_write(struct file *filp, const char __user *ubuf,
               size_t cnt, loff_t *ppos)
{
      struct trace_array *tr = filp->private_data;
      char buf[64];
      unsigned long val;
      int ret;

      if (cnt >= sizeof(buf))
            return -EINVAL;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      ret = strict_strtoul(buf, 10, &val);
      if (ret < 0)
            return ret;

      val = !!val;

      mutex_lock(&trace_types_lock);
      if (tracer_enabled ^ val) {
            if (val) {
                  tracer_enabled = 1;
                  if (current_trace->start)
                        current_trace->start(tr);
                  tracing_start();
            } else {
                  tracer_enabled = 0;
                  tracing_stop();
                  if (current_trace->stop)
                        current_trace->stop(tr);
            }
      }
      mutex_unlock(&trace_types_lock);

      filp->f_pos += cnt;

      return cnt;
}

static ssize_t
tracing_set_trace_read(struct file *filp, char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
      char buf[max_tracer_type_len+2];
      int r;

      mutex_lock(&trace_types_lock);
      if (current_trace)
            r = sprintf(buf, "%s\n", current_trace->name);
      else
            r = sprintf(buf, "\n");
      mutex_unlock(&trace_types_lock);

      return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

int tracer_init(struct tracer *t, struct trace_array *tr)
{
      tracing_reset_online_cpus(tr);
      return t->init(tr);
}

static int tracing_resize_ring_buffer(unsigned long size)
{
      int ret;

      /*
       * If kernel or user changes the size of the ring buffer
       * we use the size that was given, and we can forget about
       * expanding it later.
       */
      ring_buffer_expanded = 1;

      ret = ring_buffer_resize(global_trace.buffer, size);
      if (ret < 0)
            return ret;

      ret = ring_buffer_resize(max_tr.buffer, size);
      if (ret < 0) {
            int r;

            r = ring_buffer_resize(global_trace.buffer,
                               global_trace.entries);
            if (r < 0) {
                  /*
                   * AARGH! We are left with different
                   * size max buffer!!!!
                   * The max buffer is our "snapshot" buffer.
                   * When a tracer needs a snapshot (one of the
                   * latency tracers), it swaps the max buffer
                   * with the saved snap shot. We succeeded to
                   * update the size of the main buffer, but failed to
                   * update the size of the max buffer. But when we tried
                   * to reset the main buffer to the original size, we
                   * failed there too. This is very unlikely to
                   * happen, but if it does, warn and kill all
                   * tracing.
                   */
                  WARN_ON(1);
                  tracing_disabled = 1;
            }
            return ret;
      }

      global_trace.entries = size;

      return ret;
}

/**
 * tracing_update_buffers - used by tracing facility to expand ring buffers
 *
 * To save on memory when the tracing is never used on a system with it
 * configured in. The ring buffers are set to a minimum size. But once
 * a user starts to use the tracing facility, then they need to grow
 * to their default size.
 *
 * This function is to be called when a tracer is about to be used.
 */
int tracing_update_buffers(void)
{
      int ret = 0;

      mutex_lock(&trace_types_lock);
      if (!ring_buffer_expanded)
            ret = tracing_resize_ring_buffer(trace_buf_size);
      mutex_unlock(&trace_types_lock);

      return ret;
}

struct trace_option_dentry;

static struct trace_option_dentry *
create_trace_option_files(struct tracer *tracer);

static void
destroy_trace_option_files(struct trace_option_dentry *topts);

static int tracing_set_tracer(const char *buf)
{
      static struct trace_option_dentry *topts;
      struct trace_array *tr = &global_trace;
      struct tracer *t;
      int ret = 0;

      mutex_lock(&trace_types_lock);

      if (!ring_buffer_expanded) {
            ret = tracing_resize_ring_buffer(trace_buf_size);
            if (ret < 0)
                  goto out;
            ret = 0;
      }

      for (t = trace_types; t; t = t->next) {
            if (strcmp(t->name, buf) == 0)
                  break;
      }
      if (!t) {
            ret = -EINVAL;
            goto out;
      }
      if (t == current_trace)
            goto out;

      trace_branch_disable();
      if (current_trace && current_trace->reset)
            current_trace->reset(tr);

      destroy_trace_option_files(topts);

      current_trace = t;

      topts = create_trace_option_files(current_trace);

      if (t->init) {
            ret = tracer_init(t, tr);
            if (ret)
                  goto out;
      }

      trace_branch_enable(tr);
 out:
      mutex_unlock(&trace_types_lock);

      return ret;
}

static ssize_t
tracing_set_trace_write(struct file *filp, const char __user *ubuf,
                  size_t cnt, loff_t *ppos)
{
      char buf[max_tracer_type_len+1];
      int i;
      size_t ret;
      int err;

      ret = cnt;

      if (cnt > max_tracer_type_len)
            cnt = max_tracer_type_len;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      /* strip ending whitespace. */
      for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
            buf[i] = 0;

      err = tracing_set_tracer(buf);
      if (err)
            return err;

      filp->f_pos += ret;

      return ret;
}

static ssize_t
tracing_max_lat_read(struct file *filp, char __user *ubuf,
                 size_t cnt, loff_t *ppos)
{
      unsigned long *ptr = filp->private_data;
      char buf[64];
      int r;

      r = snprintf(buf, sizeof(buf), "%ld\n",
                 *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
      if (r > sizeof(buf))
            r = sizeof(buf);
      return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static ssize_t
tracing_max_lat_write(struct file *filp, const char __user *ubuf,
                  size_t cnt, loff_t *ppos)
{
      unsigned long *ptr = filp->private_data;
      char buf[64];
      unsigned long val;
      int ret;

      if (cnt >= sizeof(buf))
            return -EINVAL;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      ret = strict_strtoul(buf, 10, &val);
      if (ret < 0)
            return ret;

      *ptr = val * 1000;

      return cnt;
}

static int tracing_open_pipe(struct inode *inode, struct file *filp)
{
      long cpu_file = (long) inode->i_private;
      struct trace_iterator *iter;
      int ret = 0;

      if (tracing_disabled)
            return -ENODEV;

      mutex_lock(&trace_types_lock);

      /* We only allow one reader per cpu */
      if (cpu_file == TRACE_PIPE_ALL_CPU) {
            if (!cpumask_empty(tracing_reader_cpumask)) {
                  ret = -EBUSY;
                  goto out;
            }
            cpumask_setall(tracing_reader_cpumask);
      } else {
            if (!cpumask_test_cpu(cpu_file, tracing_reader_cpumask))
                  cpumask_set_cpu(cpu_file, tracing_reader_cpumask);
            else {
                  ret = -EBUSY;
                  goto out;
            }
      }

      /* create a buffer to store the information to pass to userspace */
      iter = kzalloc(sizeof(*iter), GFP_KERNEL);
      if (!iter) {
            ret = -ENOMEM;
            goto out;
      }

      /*
       * We make a copy of the current tracer to avoid concurrent
       * changes on it while we are reading.
       */
      iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
      if (!iter->trace) {
            ret = -ENOMEM;
            goto fail;
      }
      if (current_trace)
            *iter->trace = *current_trace;

      if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
            ret = -ENOMEM;
            goto fail;
      }

      /* trace pipe does not show start of buffer */
      cpumask_setall(iter->started);

      if (trace_flags & TRACE_ITER_LATENCY_FMT)
            iter->iter_flags |= TRACE_FILE_LAT_FMT;

      iter->cpu_file = cpu_file;
      iter->tr = &global_trace;
      mutex_init(&iter->mutex);
      filp->private_data = iter;

      if (iter->trace->pipe_open)
            iter->trace->pipe_open(iter);

out:
      mutex_unlock(&trace_types_lock);
      return ret;

fail:
      kfree(iter->trace);
      kfree(iter);
      mutex_unlock(&trace_types_lock);
      return ret;
}

static int tracing_release_pipe(struct inode *inode, struct file *file)
{
      struct trace_iterator *iter = file->private_data;

      mutex_lock(&trace_types_lock);

      if (iter->cpu_file == TRACE_PIPE_ALL_CPU)
            cpumask_clear(tracing_reader_cpumask);
      else
            cpumask_clear_cpu(iter->cpu_file, tracing_reader_cpumask);

      mutex_unlock(&trace_types_lock);

      free_cpumask_var(iter->started);
      mutex_destroy(&iter->mutex);
      kfree(iter->trace);
      kfree(iter);

      return 0;
}

static unsigned int
tracing_poll_pipe(struct file *filp, poll_table *poll_table)
{
      struct trace_iterator *iter = filp->private_data;

      if (trace_flags & TRACE_ITER_BLOCK) {
            /*
             * Always select as readable when in blocking mode
             */
            return POLLIN | POLLRDNORM;
      } else {
            if (!trace_empty(iter))
                  return POLLIN | POLLRDNORM;
            poll_wait(filp, &trace_wait, poll_table);
            if (!trace_empty(iter))
                  return POLLIN | POLLRDNORM;

            return 0;
      }
}


void default_wait_pipe(struct trace_iterator *iter)
{
      DEFINE_WAIT(wait);

      prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);

      if (trace_empty(iter))
            schedule();

      finish_wait(&trace_wait, &wait);
}

/*
 * This is a make-shift waitqueue.
 * A tracer might use this callback on some rare cases:
 *
 *  1) the current tracer might hold the runqueue lock when it wakes up
 *     a reader, hence a deadlock (sched, function, and function graph tracers)
 *  2) the function tracers, trace all functions, we don't want
 *     the overhead of calling wake_up and friends
 *     (and tracing them too)
 *
 *     Anyway, this is really very primitive wakeup.
 */
void poll_wait_pipe(struct trace_iterator *iter)
{
      set_current_state(TASK_INTERRUPTIBLE);
      /* sleep for 100 msecs, and try again. */
      schedule_timeout(HZ / 10);
}

/* Must be called with trace_types_lock mutex held. */
static int tracing_wait_pipe(struct file *filp)
{
      struct trace_iterator *iter = filp->private_data;

      while (trace_empty(iter)) {

            if ((filp->f_flags & O_NONBLOCK)) {
                  return -EAGAIN;
            }

            mutex_unlock(&iter->mutex);

            iter->trace->wait_pipe(iter);

            mutex_lock(&iter->mutex);

            if (signal_pending(current))
                  return -EINTR;

            /*
             * We block until we read something and tracing is disabled.
             * We still block if tracing is disabled, but we have never
             * read anything. This allows a user to cat this file, and
             * then enable tracing. But after we have read something,
             * we give an EOF when tracing is again disabled.
             *
             * iter->pos will be 0 if we haven't read anything.
             */
            if (!tracer_enabled && iter->pos)
                  break;
      }

      return 1;
}

/*
 * Consumer reader.
 */
static ssize_t
tracing_read_pipe(struct file *filp, char __user *ubuf,
              size_t cnt, loff_t *ppos)
{
      struct trace_iterator *iter = filp->private_data;
      static struct tracer *old_tracer;
      ssize_t sret;

      /* return any leftover data */
      sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
      if (sret != -EBUSY)
            return sret;

      trace_seq_init(&iter->seq);

      /* copy the tracer to avoid using a global lock all around */
      mutex_lock(&trace_types_lock);
      if (unlikely(old_tracer != current_trace && current_trace)) {
            old_tracer = current_trace;
            *iter->trace = *current_trace;
      }
      mutex_unlock(&trace_types_lock);

      /*
       * Avoid more than one consumer on a single file descriptor
       * This is just a matter of traces coherency, the ring buffer itself
       * is protected.
       */
      mutex_lock(&iter->mutex);
      if (iter->trace->read) {
            sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
            if (sret)
                  goto out;
      }

waitagain:
      sret = tracing_wait_pipe(filp);
      if (sret <= 0)
            goto out;

      /* stop when tracing is finished */
      if (trace_empty(iter)) {
            sret = 0;
            goto out;
      }

      if (cnt >= PAGE_SIZE)
            cnt = PAGE_SIZE - 1;

      /* reset all but tr, trace, and overruns */
      memset(&iter->seq, 0,
             sizeof(struct trace_iterator) -
             offsetof(struct trace_iterator, seq));
      iter->pos = -1;

      trace_event_read_lock();
      while (find_next_entry_inc(iter) != NULL) {
            enum print_line_t ret;
            int len = iter->seq.len;

            ret = print_trace_line(iter);
            if (ret == TRACE_TYPE_PARTIAL_LINE) {
                  /* don't print partial lines */
                  iter->seq.len = len;
                  break;
            }
            if (ret != TRACE_TYPE_NO_CONSUME)
                  trace_consume(iter);

            if (iter->seq.len >= cnt)
                  break;
      }
      trace_event_read_unlock();

      /* Now copy what we have to the user */
      sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
      if (iter->seq.readpos >= iter->seq.len)
            trace_seq_init(&iter->seq);

      /*
       * If there was nothing to send to user, inspite of consuming trace
       * entries, go back to wait for more entries.
       */
      if (sret == -EBUSY)
            goto waitagain;

out:
      mutex_unlock(&iter->mutex);

      return sret;
}

static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
                             struct pipe_buffer *buf)
{
      __free_page(buf->page);
}

static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
                             unsigned int idx)
{
      __free_page(spd->pages[idx]);
}

static struct pipe_buf_operations tracing_pipe_buf_ops = {
      .can_merge        = 0,
      .map              = generic_pipe_buf_map,
      .unmap                  = generic_pipe_buf_unmap,
      .confirm          = generic_pipe_buf_confirm,
      .release          = tracing_pipe_buf_release,
      .steal                  = generic_pipe_buf_steal,
      .get              = generic_pipe_buf_get,
};

static size_t
tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
{
      size_t count;
      int ret;

      /* Seq buffer is page-sized, exactly what we need. */
      for (;;) {
            count = iter->seq.len;
            ret = print_trace_line(iter);
            count = iter->seq.len - count;
            if (rem < count) {
                  rem = 0;
                  iter->seq.len -= count;
                  break;
            }
            if (ret == TRACE_TYPE_PARTIAL_LINE) {
                  iter->seq.len -= count;
                  break;
            }

            if (ret != TRACE_TYPE_NO_CONSUME)
                  trace_consume(iter);
            rem -= count;
            if (!find_next_entry_inc(iter))     {
                  rem = 0;
                  iter->ent = NULL;
                  break;
            }
      }

      return rem;
}

static ssize_t tracing_splice_read_pipe(struct file *filp,
                              loff_t *ppos,
                              struct pipe_inode_info *pipe,
                              size_t len,
                              unsigned int flags)
{
      struct page *pages[PIPE_BUFFERS];
      struct partial_page partial[PIPE_BUFFERS];
      struct trace_iterator *iter = filp->private_data;
      struct splice_pipe_desc spd = {
            .pages            = pages,
            .partial    = partial,
            .nr_pages   = 0, /* This gets updated below. */
            .flags            = flags,
            .ops        = &tracing_pipe_buf_ops,
            .spd_release      = tracing_spd_release_pipe,
      };
      static struct tracer *old_tracer;
      ssize_t ret;
      size_t rem;
      unsigned int i;

      /* copy the tracer to avoid using a global lock all around */
      mutex_lock(&trace_types_lock);
      if (unlikely(old_tracer != current_trace && current_trace)) {
            old_tracer = current_trace;
            *iter->trace = *current_trace;
      }
      mutex_unlock(&trace_types_lock);

      mutex_lock(&iter->mutex);

      if (iter->trace->splice_read) {
            ret = iter->trace->splice_read(iter, filp,
                                     ppos, pipe, len, flags);
            if (ret)
                  goto out_err;
      }

      ret = tracing_wait_pipe(filp);
      if (ret <= 0)
            goto out_err;

      if (!iter->ent && !find_next_entry_inc(iter)) {
            ret = -EFAULT;
            goto out_err;
      }

      trace_event_read_lock();

      /* Fill as many pages as possible. */
      for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
            pages[i] = alloc_page(GFP_KERNEL);
            if (!pages[i])
                  break;

            rem = tracing_fill_pipe_page(rem, iter);

            /* Copy the data into the page, so we can start over. */
            ret = trace_seq_to_buffer(&iter->seq,
                                page_address(pages[i]),
                                iter->seq.len);
            if (ret < 0) {
                  __free_page(pages[i]);
                  break;
            }
            partial[i].offset = 0;
            partial[i].len = iter->seq.len;

            trace_seq_init(&iter->seq);
      }

      trace_event_read_unlock();
      mutex_unlock(&iter->mutex);

      spd.nr_pages = i;

      return splice_to_pipe(pipe, &spd);

out_err:
      mutex_unlock(&iter->mutex);

      return ret;
}

static ssize_t
tracing_entries_read(struct file *filp, char __user *ubuf,
                 size_t cnt, loff_t *ppos)
{
      struct trace_array *tr = filp->private_data;
      char buf[96];
      int r;

      mutex_lock(&trace_types_lock);
      if (!ring_buffer_expanded)
            r = sprintf(buf, "%lu (expanded: %lu)\n",
                      tr->entries >> 10,
                      trace_buf_size >> 10);
      else
            r = sprintf(buf, "%lu\n", tr->entries >> 10);
      mutex_unlock(&trace_types_lock);

      return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static ssize_t
tracing_entries_write(struct file *filp, const char __user *ubuf,
                  size_t cnt, loff_t *ppos)
{
      unsigned long val;
      char buf[64];
      int ret, cpu;

      if (cnt >= sizeof(buf))
            return -EINVAL;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      ret = strict_strtoul(buf, 10, &val);
      if (ret < 0)
            return ret;

      /* must have at least 1 entry */
      if (!val)
            return -EINVAL;

      mutex_lock(&trace_types_lock);

      tracing_stop();

      /* disable all cpu buffers */
      for_each_tracing_cpu(cpu) {
            if (global_trace.data[cpu])
                  atomic_inc(&global_trace.data[cpu]->disabled);
            if (max_tr.data[cpu])
                  atomic_inc(&max_tr.data[cpu]->disabled);
      }

      /* value is in KB */
      val <<= 10;

      if (val != global_trace.entries) {
            ret = tracing_resize_ring_buffer(val);
            if (ret < 0) {
                  cnt = ret;
                  goto out;
            }
      }

      filp->f_pos += cnt;

      /* If check pages failed, return ENOMEM */
      if (tracing_disabled)
            cnt = -ENOMEM;
 out:
      for_each_tracing_cpu(cpu) {
            if (global_trace.data[cpu])
                  atomic_dec(&global_trace.data[cpu]->disabled);
            if (max_tr.data[cpu])
                  atomic_dec(&max_tr.data[cpu]->disabled);
      }

      tracing_start();
      max_tr.entries = global_trace.entries;
      mutex_unlock(&trace_types_lock);

      return cnt;
}

static int mark_printk(const char *fmt, ...)
{
      int ret;
      va_list args;
      va_start(args, fmt);
      ret = trace_vprintk(0, fmt, args);
      va_end(args);
      return ret;
}

static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
                              size_t cnt, loff_t *fpos)
{
      char *buf;
      char *end;

      if (tracing_disabled)
            return -EINVAL;

      if (cnt > TRACE_BUF_SIZE)
            cnt = TRACE_BUF_SIZE;

      buf = kmalloc(cnt + 1, GFP_KERNEL);
      if (buf == NULL)
            return -ENOMEM;

      if (copy_from_user(buf, ubuf, cnt)) {
            kfree(buf);
            return -EFAULT;
      }

      /* Cut from the first nil or newline. */
      buf[cnt] = '\0';
      end = strchr(buf, '\n');
      if (end)
            *end = '\0';

      cnt = mark_printk("%s\n", buf);
      kfree(buf);
      *fpos += cnt;

      return cnt;
}

static const struct file_operations tracing_max_lat_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_max_lat_read,
      .write            = tracing_max_lat_write,
};

static const struct file_operations tracing_ctrl_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_ctrl_read,
      .write            = tracing_ctrl_write,
};

static const struct file_operations set_tracer_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_set_trace_read,
      .write            = tracing_set_trace_write,
};

static const struct file_operations tracing_pipe_fops = {
      .open       = tracing_open_pipe,
      .poll       = tracing_poll_pipe,
      .read       = tracing_read_pipe,
      .splice_read      = tracing_splice_read_pipe,
      .release    = tracing_release_pipe,
};

static const struct file_operations tracing_entries_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_entries_read,
      .write            = tracing_entries_write,
};

static const struct file_operations tracing_mark_fops = {
      .open       = tracing_open_generic,
      .write            = tracing_mark_write,
};

03356 struct ftrace_buffer_info {
      struct trace_array      *tr;
      void              *spare;
      int               cpu;
      unsigned int            read;
};

static int tracing_buffers_open(struct inode *inode, struct file *filp)
{
      int cpu = (int)(long)inode->i_private;
      struct ftrace_buffer_info *info;

      if (tracing_disabled)
            return -ENODEV;

      info = kzalloc(sizeof(*info), GFP_KERNEL);
      if (!info)
            return -ENOMEM;

      info->tr    = &global_trace;
      info->cpu   = cpu;
      info->spare = NULL;
      /* Force reading ring buffer for first read */
      info->read  = (unsigned int)-1;

      filp->private_data = info;

      return nonseekable_open(inode, filp);
}

static ssize_t
tracing_buffers_read(struct file *filp, char __user *ubuf,
                 size_t count, loff_t *ppos)
{
      struct ftrace_buffer_info *info = filp->private_data;
      unsigned int pos;
      ssize_t ret;
      size_t size;

      if (!count)
            return 0;

      if (!info->spare)
            info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
      if (!info->spare)
            return -ENOMEM;

      /* Do we have previous read data to read? */
      if (info->read < PAGE_SIZE)
            goto read;

      info->read = 0;

      ret = ring_buffer_read_page(info->tr->buffer,
                            &info->spare,
                            count,
                            info->cpu, 0);
      if (ret < 0)
            return 0;

      pos = ring_buffer_page_len(info->spare);

      if (pos < PAGE_SIZE)
            memset(info->spare + pos, 0, PAGE_SIZE - pos);

read:
      size = PAGE_SIZE - info->read;
      if (size > count)
            size = count;

      ret = copy_to_user(ubuf, info->spare + info->read, size);
      if (ret == size)
            return -EFAULT;
      size -= ret;

      *ppos += size;
      info->read += size;

      return size;
}

static int tracing_buffers_release(struct inode *inode, struct file *file)
{
      struct ftrace_buffer_info *info = file->private_data;

      if (info->spare)
            ring_buffer_free_read_page(info->tr->buffer, info->spare);
      kfree(info);

      return 0;
}

03448 struct buffer_ref {
      struct ring_buffer      *buffer;
      void              *page;
      int               ref;
};

static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
                            struct pipe_buffer *buf)
{
      struct buffer_ref *ref = (struct buffer_ref *)buf->private;

      if (--ref->ref)
            return;

      ring_buffer_free_read_page(ref->buffer, ref->page);
      kfree(ref);
      buf->private = 0;
}

static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
                         struct pipe_buffer *buf)
{
      return 1;
}

static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
                        struct pipe_buffer *buf)
{
      struct buffer_ref *ref = (struct buffer_ref *)buf->private;

      ref->ref++;
}

/* Pipe buffer operations for a buffer. */
static struct pipe_buf_operations buffer_pipe_buf_ops = {
      .can_merge        = 0,
      .map              = generic_pipe_buf_map,
      .unmap                  = generic_pipe_buf_unmap,
      .confirm          = generic_pipe_buf_confirm,
      .release          = buffer_pipe_buf_release,
      .steal                  = buffer_pipe_buf_steal,
      .get              = buffer_pipe_buf_get,
};

/*
 * Callback from splice_to_pipe(), if we need to release some pages
 * at the end of the spd in case we error'ed out in filling the pipe.
 */
static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
{
      struct buffer_ref *ref =
            (struct buffer_ref *)spd->partial[i].private;

      if (--ref->ref)
            return;

      ring_buffer_free_read_page(ref->buffer, ref->page);
      kfree(ref);
      spd->partial[i].private = 0;
}

static ssize_t
tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                      struct pipe_inode_info *pipe, size_t len,
                      unsigned int flags)
{
      struct ftrace_buffer_info *info = file->private_data;
      struct partial_page partial[PIPE_BUFFERS];
      struct page *pages[PIPE_BUFFERS];
      struct splice_pipe_desc spd = {
            .pages            = pages,
            .partial    = partial,
            .flags            = flags,
            .ops        = &buffer_pipe_buf_ops,
            .spd_release      = buffer_spd_release,
      };
      struct buffer_ref *ref;
      int entries, size, i;
      size_t ret;

      if (*ppos & (PAGE_SIZE - 1)) {
            WARN_ONCE(1, "Ftrace: previous read must page-align\n");
            return -EINVAL;
      }

      if (len & (PAGE_SIZE - 1)) {
            WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
            if (len < PAGE_SIZE)
                  return -EINVAL;
            len &= PAGE_MASK;
      }

      entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);

      for (i = 0; i < PIPE_BUFFERS && len && entries; i++, len -= PAGE_SIZE) {
            struct page *page;
            int r;

            ref = kzalloc(sizeof(*ref), GFP_KERNEL);
            if (!ref)
                  break;

            ref->ref = 1;
            ref->buffer = info->tr->buffer;
            ref->page = ring_buffer_alloc_read_page(ref->buffer);
            if (!ref->page) {
                  kfree(ref);
                  break;
            }

            r = ring_buffer_read_page(ref->buffer, &ref->page,
                                len, info->cpu, 1);
            if (r < 0) {
                  ring_buffer_free_read_page(ref->buffer,
                                       ref->page);
                  kfree(ref);
                  break;
            }

            /*
             * zero out any left over data, this is going to
             * user land.
             */
            size = ring_buffer_page_len(ref->page);
            if (size < PAGE_SIZE)
                  memset(ref->page + size, 0, PAGE_SIZE - size);

            page = virt_to_page(ref->page);

            spd.pages[i] = page;
            spd.partial[i].len = PAGE_SIZE;
            spd.partial[i].offset = 0;
            spd.partial[i].private = (unsigned long)ref;
            spd.nr_pages++;
            *ppos += PAGE_SIZE;

            entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
      }

      spd.nr_pages = i;

      /* did we read anything? */
      if (!spd.nr_pages) {
            if (flags & SPLICE_F_NONBLOCK)
                  ret = -EAGAIN;
            else
                  ret = 0;
            /* TODO: block */
            return ret;
      }

      ret = splice_to_pipe(pipe, &spd);

      return ret;
}

static const struct file_operations tracing_buffers_fops = {
      .open       = tracing_buffers_open,
      .read       = tracing_buffers_read,
      .release    = tracing_buffers_release,
      .splice_read      = tracing_buffers_splice_read,
      .llseek           = no_llseek,
};

static ssize_t
tracing_stats_read(struct file *filp, char __user *ubuf,
               size_t count, loff_t *ppos)
{
      unsigned long cpu = (unsigned long)filp->private_data;
      struct trace_array *tr = &global_trace;
      struct trace_seq *s;
      unsigned long cnt;

      s = kmalloc(sizeof(*s), GFP_KERNEL);
      if (!s)
            return ENOMEM;

      trace_seq_init(s);

      cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
      trace_seq_printf(s, "entries: %ld\n", cnt);

      cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
      trace_seq_printf(s, "overrun: %ld\n", cnt);

      cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
      trace_seq_printf(s, "commit overrun: %ld\n", cnt);

      cnt = ring_buffer_nmi_dropped_cpu(tr->buffer, cpu);
      trace_seq_printf(s, "nmi dropped: %ld\n", cnt);

      count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);

      kfree(s);

      return count;
}

static const struct file_operations tracing_stats_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_stats_read,
};

#ifdef CONFIG_DYNAMIC_FTRACE

int __weak ftrace_arch_read_dyn_info(char *buf, int size)
{
      return 0;
}

static ssize_t
tracing_read_dyn_info(struct file *filp, char __user *ubuf,
              size_t cnt, loff_t *ppos)
{
      static char ftrace_dyn_info_buffer[1024];
      static DEFINE_MUTEX(dyn_info_mutex);
      unsigned long *p = filp->private_data;
      char *buf = ftrace_dyn_info_buffer;
      int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
      int r;

      mutex_lock(&dyn_info_mutex);
      r = sprintf(buf, "%ld ", *p);

      r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
      buf[r++] = '\n';

      r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);

      mutex_unlock(&dyn_info_mutex);

      return r;
}

static const struct file_operations tracing_dyn_info_fops = {
      .open       = tracing_open_generic,
      .read       = tracing_read_dyn_info,
};
#endif

static struct dentry *d_tracer;

struct dentry *tracing_init_dentry(void)
{
      static int once;

      if (d_tracer)
            return d_tracer;

      if (!debugfs_initialized())
            return NULL;

      d_tracer = debugfs_create_dir("tracing", NULL);

      if (!d_tracer && !once) {
            once = 1;
            pr_warning("Could not create debugfs directory 'tracing'\n");
            return NULL;
      }

      return d_tracer;
}

static struct dentry *d_percpu;

struct dentry *tracing_dentry_percpu(void)
{
      static int once;
      struct dentry *d_tracer;

      if (d_percpu)
            return d_percpu;

      d_tracer = tracing_init_dentry();

      if (!d_tracer)
            return NULL;

      d_percpu = debugfs_create_dir("per_cpu", d_tracer);

      if (!d_percpu && !once) {
            once = 1;
            pr_warning("Could not create debugfs directory 'per_cpu'\n");
            return NULL;
      }

      return d_percpu;
}

static void tracing_init_debugfs_percpu(long cpu)
{
      struct dentry *d_percpu = tracing_dentry_percpu();
      struct dentry *d_cpu;
      /* strlen(cpu) + MAX(log10(cpu)) + '\0' */
      char cpu_dir[7];

      if (cpu > 999 || cpu < 0)
            return;

      sprintf(cpu_dir, "cpu%ld", cpu);
      d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
      if (!d_cpu) {
            pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);
            return;
      }

      /* per cpu trace_pipe */
      trace_create_file("trace_pipe", 0444, d_cpu,
                  (void *) cpu, &tracing_pipe_fops);

      /* per cpu trace */
      trace_create_file("trace", 0644, d_cpu,
                  (void *) cpu, &tracing_fops);

      trace_create_file("trace_pipe_raw", 0444, d_cpu,
                  (void *) cpu, &tracing_buffers_fops);

      trace_create_file("stats", 0444, d_cpu,
                  (void *) cpu, &tracing_stats_fops);
}

#ifdef CONFIG_FTRACE_SELFTEST
/* Let selftest have access to static functions in this file */
#include "trace_selftest.c"
#endif

03774 struct trace_option_dentry {
      struct tracer_opt       *opt;
      struct tracer_flags           *flags;
      struct dentry                 *entry;
};

static ssize_t
trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
                  loff_t *ppos)
{
      struct trace_option_dentry *topt = filp->private_data;
      char *buf;

      if (topt->flags->val & topt->opt->bit)
            buf = "1\n";
      else
            buf = "0\n";

      return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}

static ssize_t
trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
                   loff_t *ppos)
{
      struct trace_option_dentry *topt = filp->private_data;
      unsigned long val;
      char buf[64];
      int ret;

      if (cnt >= sizeof(buf))
            return -EINVAL;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      ret = strict_strtoul(buf, 10, &val);
      if (ret < 0)
            return ret;

      ret = 0;
      switch (val) {
      case 0:
            /* do nothing if already cleared */
            if (!(topt->flags->val & topt->opt->bit))
                  break;

            mutex_lock(&trace_types_lock);
            if (current_trace->set_flag)
                  ret = current_trace->set_flag(topt->flags->val,
                                          topt->opt->bit, 0);
            mutex_unlock(&trace_types_lock);
            if (ret)
                  return ret;
            topt->flags->val &= ~topt->opt->bit;
            break;
      case 1:
            /* do nothing if already set */
            if (topt->flags->val & topt->opt->bit)
                  break;

            mutex_lock(&trace_types_lock);
            if (current_trace->set_flag)
                  ret = current_trace->set_flag(topt->flags->val,
                                          topt->opt->bit, 1);
            mutex_unlock(&trace_types_lock);
            if (ret)
                  return ret;
            topt->flags->val |= topt->opt->bit;
            break;

      default:
            return -EINVAL;
      }

      *ppos += cnt;

      return cnt;
}


static const struct file_operations trace_options_fops = {
      .open = tracing_open_generic,
      .read = trace_options_read,
      .write = trace_options_write,
};

static ssize_t
trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
                  loff_t *ppos)
{
      long index = (long)filp->private_data;
      char *buf;

      if (trace_flags & (1 << index))
            buf = "1\n";
      else
            buf = "0\n";

      return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}

static ssize_t
trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
                   loff_t *ppos)
{
      long index = (long)filp->private_data;
      char buf[64];
      unsigned long val;
      int ret;

      if (cnt >= sizeof(buf))
            return -EINVAL;

      if (copy_from_user(&buf, ubuf, cnt))
            return -EFAULT;

      buf[cnt] = 0;

      ret = strict_strtoul(buf, 10, &val);
      if (ret < 0)
            return ret;

      if (val != 0 && val != 1)
            return -EINVAL;
      set_tracer_flags(1 << index, val);

      *ppos += cnt;

      return cnt;
}

static const struct file_operations trace_options_core_fops = {
      .open = tracing_open_generic,
      .read = trace_options_core_read,
      .write = trace_options_core_write,
};

struct dentry *trace_create_file(const char *name,
                         mode_t mode,
                         struct dentry *parent,
                         void *data,
                         const struct file_operations *fops)
{
      struct dentry *ret;

      ret = debugfs_create_file(name, mode, parent, data, fops);
      if (!ret)
            pr_warning("Could not create debugfs '%s' entry\n", name);

      return ret;
}


static struct dentry *trace_options_init_dentry(void)
{
      struct dentry *d_tracer;
      static struct dentry *t_options;

      if (t_options)
            return t_options;

      d_tracer = tracing_init_dentry();
      if (!d_tracer)
            return NULL;

      t_options = debugfs_create_dir("options", d_tracer);
      if (!t_options) {
            pr_warning("Could not create debugfs directory 'options'\n");
            return NULL;
      }

      return t_options;
}

static void
create_trace_option_file(struct trace_option_dentry *topt,
                   struct tracer_flags *flags,
                   struct tracer_opt *opt)
{
      struct dentry *t_options;

      t_options = trace_options_init_dentry();
      if (!t_options)
            return;

      topt->flags = flags;
      topt->opt = opt;

      topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
                            &trace_options_fops);

}

static struct trace_option_dentry *
create_trace_option_files(struct tracer *tracer)
{
      struct trace_option_dentry *topts;
      struct tracer_flags *flags;
      struct tracer_opt *opts;
      int cnt;

      if (!tracer)
            return NULL;

      flags = tracer->flags;

      if (!flags || !flags->opts)
            return NULL;

      opts = flags->opts;

      for (cnt = 0; opts[cnt].name; cnt++)
            ;

      topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
      if (!topts)
            return NULL;

      for (cnt = 0; opts[cnt].name; cnt++)
            create_trace_option_file(&topts[cnt], flags,
                               &opts[cnt]);

      return topts;
}

static void
destroy_trace_option_files(struct trace_option_dentry *topts)
{
      int cnt;

      if (!topts)
            return;

      for (cnt = 0; topts[cnt].opt; cnt++) {
            if (topts[cnt].entry)
                  debugfs_remove(topts[cnt].entry);
      }

      kfree(topts);
}

static struct dentry *
create_trace_option_core_file(const char *option, long index)
{
      struct dentry *t_options;

      t_options = trace_options_init_dentry();
      if (!t_options)
            return NULL;

      return trace_create_file(option, 0644, t_options, (void *)index,
                            &trace_options_core_fops);
}

static __init void create_trace_options_dir(void)
{
      struct dentry *t_options;
      int i;

      t_options = trace_options_init_dentry();
      if (!t_options)
            return;

      for (i = 0; trace_options[i]; i++)
            create_trace_option_core_file(trace_options[i], i);
}

static __init int tracer_init_debugfs(void)
{
      struct dentry *d_tracer;
      int cpu;

      d_tracer = tracing_init_dentry();

      trace_create_file("tracing_enabled", 0644, d_tracer,
                  &global_trace, &tracing_ctrl_fops);

      trace_create_file("trace_options", 0644, d_tracer,
                  NULL, &tracing_iter_fops);

      trace_create_file("tracing_cpumask", 0644, d_tracer,
                  NULL, &tracing_cpumask_fops);

      trace_create_file("trace", 0644, d_tracer,
                  (void *) TRACE_PIPE_ALL_CPU, &tracing_fops);

      trace_create_file("available_tracers", 0444, d_tracer,
                  &global_trace, &show_traces_fops);

      trace_create_file("current_tracer", 0644, d_tracer,
                  &global_trace, &set_tracer_fops);

      trace_create_file("tracing_max_latency", 0644, d_tracer,
                  &tracing_max_latency, &tracing_max_lat_fops);

      trace_create_file("tracing_thresh", 0644, d_tracer,
                  &tracing_thresh, &tracing_max_lat_fops);

      trace_create_file("README", 0444, d_tracer,
                  NULL, &tracing_readme_fops);

      trace_create_file("trace_pipe", 0444, d_tracer,
                  (void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);

      trace_create_file("buffer_size_kb", 0644, d_tracer,
                  &global_trace, &tracing_entries_fops);

      trace_create_file("trace_marker", 0220, d_tracer,
                  NULL, &tracing_mark_fops);

      trace_create_file("saved_cmdlines", 0444, d_tracer,
                  NULL, &tracing_saved_cmdlines_fops);

#ifdef CONFIG_DYNAMIC_FTRACE
      trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
                  &ftrace_update_tot_cnt, &tracing_dyn_info_fops);
#endif
#ifdef CONFIG_SYSPROF_TRACER
      init_tracer_sysprof_debugfs(d_tracer);
#endif

      create_trace_options_dir();

      for_each_tracing_cpu(cpu)
            tracing_init_debugfs_percpu(cpu);

      return 0;
}

static int trace_panic_handler(struct notifier_block *this,
                         unsigned long event, void *unused)
{
      if (ftrace_dump_on_oops)
            ftrace_dump();
      return NOTIFY_OK;
}

static struct notifier_block trace_panic_notifier = {
      .notifier_call  = trace_panic_handler,
      .next           = NULL,
      .priority       = 150   /* priority: INT_MAX >= x >= 0 */
};

static int trace_die_handler(struct notifier_block *self,
                       unsigned long val,
                       void *data)
{
      switch (val) {
      case DIE_OOPS:
            if (ftrace_dump_on_oops)
                  ftrace_dump();
            break;
      default:
            break;
      }
      return NOTIFY_OK;
}

static struct notifier_block trace_die_notifier = {
      .notifier_call = trace_die_handler,
      .priority = 200
};

/*
 * printk is set to max of 1024, we really don't need it that big.
 * Nothing should be printing 1000 characters anyway.
 */
#define TRACE_MAX_PRINT       1000

/*
 * Define here KERN_TRACE so that we have one place to modify
 * it if we decide to change what log level the ftrace dump
 * should be at.
 */
#define KERN_TRACE            KERN_EMERG

static void
trace_printk_seq(struct trace_seq *s)
{
      /* Probably should print a warning here. */
      if (s->len >= 1000)
            s->len = 1000;

      /* should be zero ended, but we are paranoid. */
      s->buffer[s->len] = 0;

      printk(KERN_TRACE "%s", s->buffer);

      trace_seq_init(s);
}

static void __ftrace_dump(bool disable_tracing)
{
      static raw_spinlock_t ftrace_dump_lock =
            (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
      /* use static because iter can be a bit big for the stack */
      static struct trace_iterator iter;
      unsigned int old_userobj;
      static int dump_ran;
      unsigned long flags;
      int cnt = 0, cpu;

      /* only one dump */
      local_irq_save(flags);
      __raw_spin_lock(&ftrace_dump_lock);
      if (dump_ran)
            goto out;

      dump_ran = 1;

      tracing_off();

      if (disable_tracing)
            ftrace_kill();

      for_each_tracing_cpu(cpu) {
            atomic_inc(&global_trace.data[cpu]->disabled);
      }

      old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;

      /* don't look at user memory in panic mode */
      trace_flags &= ~TRACE_ITER_SYM_USEROBJ;

      printk(KERN_TRACE "Dumping ftrace buffer:\n");

      /* Simulate the iterator */
      iter.tr = &global_trace;
      iter.trace = current_trace;
      iter.cpu_file = TRACE_PIPE_ALL_CPU;

      /*
       * We need to stop all tracing on all CPUS to read the
       * the next buffer. This is a bit expensive, but is
       * not done often. We fill all what we can read,
       * and then release the locks again.
       */

      while (!trace_empty(&iter)) {

            if (!cnt)
                  printk(KERN_TRACE "---------------------------------\n");

            cnt++;

            /* reset all but tr, trace, and overruns */
            memset(&iter.seq, 0,
                   sizeof(struct trace_iterator) -
                   offsetof(struct trace_iterator, seq));
            iter.iter_flags |= TRACE_FILE_LAT_FMT;
            iter.pos = -1;

            if (find_next_entry_inc(&iter) != NULL) {
                  int ret;

                  ret = print_trace_line(&iter);
                  if (ret != TRACE_TYPE_NO_CONSUME)
                        trace_consume(&iter);
            }

            trace_printk_seq(&iter.seq);
      }

      if (!cnt)
            printk(KERN_TRACE "   (ftrace buffer empty)\n");
      else
            printk(KERN_TRACE "---------------------------------\n");

      /* Re-enable tracing if requested */
      if (!disable_tracing) {
            trace_flags |= old_userobj;

            for_each_tracing_cpu(cpu) {
                  atomic_dec(&global_trace.data[cpu]->disabled);
            }
            tracing_on();
      }

 out:
      __raw_spin_unlock(&ftrace_dump_lock);
      local_irq_restore(flags);
}

/* By default: disable tracing after the dump */
void ftrace_dump(void)
{
      __ftrace_dump(true);
}

__init static int tracer_alloc_buffers(void)
{
      struct trace_array_cpu *data;
      int ring_buf_size;
      int i;
      int ret = -ENOMEM;

      if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
            goto out;

      if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
            goto out_free_buffer_mask;

      if (!alloc_cpumask_var(&tracing_reader_cpumask, GFP_KERNEL))
            goto out_free_tracing_cpumask;

      /* To save memory, keep the ring buffer size to its minimum */
      if (ring_buffer_expanded)
            ring_buf_size = trace_buf_size;
      else
            ring_buf_size = 1;

      cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
      cpumask_copy(tracing_cpumask, cpu_all_mask);
      cpumask_clear(tracing_reader_cpumask);

      /* TODO: make the number of buffers hot pluggable with CPUS */
      global_trace.buffer = ring_buffer_alloc(ring_buf_size,
                                       TRACE_BUFFER_FLAGS);
      if (!global_trace.buffer) {
            printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
            WARN_ON(1);
            goto out_free_cpumask;
      }
      global_trace.entries = ring_buffer_size(global_trace.buffer);


#ifdef CONFIG_TRACER_MAX_TRACE
      max_tr.buffer = ring_buffer_alloc(ring_buf_size,
                                   TRACE_BUFFER_FLAGS);
      if (!max_tr.buffer) {
            printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
            WARN_ON(1);
            ring_buffer_free(global_trace.buffer);
            goto out_free_cpumask;
      }
      max_tr.entries = ring_buffer_size(max_tr.buffer);
      WARN_ON(max_tr.entries != global_trace.entries);
#endif

      /* Allocate the first page for all buffers */
      for_each_tracing_cpu(i) {
            data = global_trace.data[i] = &per_cpu(global_trace_cpu, i);
            max_tr.data[i] = &per_cpu(max_data, i);
      }

      trace_init_cmdlines();

      register_tracer(&nop_trace);
      current_trace = &nop_trace;
#ifdef CONFIG_BOOT_TRACER
      register_tracer(&boot_tracer);
#endif
      /* All seems OK, enable tracing */
      tracing_disabled = 0;

      atomic_notifier_chain_register(&panic_notifier_list,
                               &trace_panic_notifier);

      register_die_notifier(&trace_die_notifier);

      return 0;

out_free_cpumask:
      free_cpumask_var(tracing_reader_cpumask);
out_free_tracing_cpumask:
      free_cpumask_var(tracing_cpumask);
out_free_buffer_mask:
      free_cpumask_var(tracing_buffer_mask);
out:
      return ret;
}

__init static int clear_boot_tracer(void)
{
      /*
       * The default tracer at boot buffer is an init section.
       * This function is called in lateinit. If we did not
       * find the boot tracer, then clear it out, to prevent
       * later registration from accessing the buffer that is
       * about to be freed.
       */
      if (!default_bootup_tracer)
            return 0;

      printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
             default_bootup_tracer);
      default_bootup_tracer = NULL;

      return 0;
}

early_initcall(tracer_alloc_buffers);
fs_initcall(tracer_init_debugfs);
late_initcall(clear_boot_tracer);

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