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