kernel/trace/trace_sched_switch.c

   1 /*
   2  * trace context switch
   3  *
   4  * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
   5  *
   6  */
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/debugfs.h>
  10 #include <linux/kallsyms.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/ftrace.h>
  13 #include <trace/events/sched.h>
  14
  15 #include "trace.h"
  16
  17 static int                      sched_ref;
  18 static DEFINE_MUTEX(sched_register_mutex);
  19
  20 static void
  21 probe_sched_switch(void *ignore, struct task_struct *prev, struct task_struct *next)
  22 {
  23         if (unlikely(!sched_ref))
  24                 return;
  25
  26         tracing_record_cmdline(prev);
  27         tracing_record_cmdline(next);
  28 }
  29
  30 static void
  31 probe_sched_wakeup(void *ignore, struct task_struct *wakee, int success)
  32 {
  33         if (unlikely(!sched_ref))
  34                 return;
  35
  36         tracing_record_cmdline(current);
  37 }
  38
  39 static int tracing_sched_register(void)
  40 {
  41         int ret;
  42
  43         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
  44         if (ret) {
  45                 pr_info("wakeup trace: Couldn't activate tracepoint"
  46                         " probe to kernel_sched_wakeup\n");
  47                 return ret;
  48         }
  49
  50         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  51         if (ret) {
  52                 pr_info("wakeup trace: Couldn't activate tracepoint"
  53                         " probe to kernel_sched_wakeup_new\n");
  54                 goto fail_deprobe;
  55         }
  56
  57         ret = register_trace_sched_switch(probe_sched_switch, NULL);
  58         if (ret) {
  59                 pr_info("sched trace: Couldn't activate tracepoint"
  60                         " probe to kernel_sched_switch\n");
  61                 goto fail_deprobe_wake_new;
  62         }
  63
  64         return ret;
  65 fail_deprobe_wake_new:
  66         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  67 fail_deprobe:
  68         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  69         return ret;
  70 }
  71
  72 static void tracing_sched_unregister(void)
  73 {
  74         unregister_trace_sched_switch(probe_sched_switch, NULL);
  75         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  76         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  77 }
  78
  79 static void tracing_start_sched_switch(void)
  80 {
  81         mutex_lock(&sched_register_mutex);
  82         if (!(sched_ref++))
  83                 tracing_sched_register();
  84         mutex_unlock(&sched_register_mutex);
  85 }
  86
  87 static void tracing_stop_sched_switch(void)
  88 {
  89         mutex_lock(&sched_register_mutex);
  90         if (!(--sched_ref))
  91                 tracing_sched_unregister();
  92         mutex_unlock(&sched_register_mutex);
  93 }
  94
  95 void tracing_start_cmdline_record(void)
  96 {
  97         tracing_start_sched_switch();
  98 }
  99
 100 void tracing_stop_cmdline_record(void)
 101 {
 102         tracing_stop_sched_switch();
 103 }