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, bool preempt,
  20                    struct task_struct *prev, struct task_struct *next)
  21 {
  22         if (unlikely(!sched_ref))
  23                 return;
  24
  25         tracing_record_cmdline(prev);
  26         tracing_record_cmdline(next);
  27 }
  28
  29 static void
  30 probe_sched_wakeup(void *ignore, struct task_struct *wakee)
  31 {
  32         if (unlikely(!sched_ref))
  33                 return;
  34
  35         tracing_record_cmdline(current);
  36 }
  37
  38 static int tracing_sched_register(void)
  39 {
  40         int ret;
  41
  42         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
  43         if (ret) {
  44                 pr_info("wakeup trace: Couldn't activate tracepoint"
  45                         " probe to kernel_sched_wakeup\n");
  46                 return ret;
  47         }
  48
  49         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  50         if (ret) {
  51                 pr_info("wakeup trace: Couldn't activate tracepoint"
  52                         " probe to kernel_sched_wakeup_new\n");
  53                 goto fail_deprobe;
  54         }
  55
  56         ret = register_trace_sched_switch(probe_sched_switch, NULL);
  57         if (ret) {
  58                 pr_info("sched trace: Couldn't activate tracepoint"
  59                         " probe to kernel_sched_switch\n");
  60                 goto fail_deprobe_wake_new;
  61         }
  62
  63         return ret;
  64 fail_deprobe_wake_new:
  65         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  66 fail_deprobe:
  67         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  68         return ret;
  69 }
  70
  71 static void tracing_sched_unregister(void)
  72 {
  73         unregister_trace_sched_switch(probe_sched_switch, NULL);
  74         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  75         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  76 }
  77
  78 static void tracing_start_sched_switch(void)
  79 {
  80         mutex_lock(&sched_register_mutex);
  81         if (!(sched_ref++))
  82                 tracing_sched_register();
  83         mutex_unlock(&sched_register_mutex);
  84 }
  85
  86 static void tracing_stop_sched_switch(void)
  87 {
  88         mutex_lock(&sched_register_mutex);
  89         if (!(--sched_ref))
  90                 tracing_sched_unregister();
  91         mutex_unlock(&sched_register_mutex);
  92 }
  93
  94 void tracing_start_cmdline_record(void)
  95 {
  96         tracing_start_sched_switch();
  97 }
  98
  99 void tracing_stop_cmdline_record(void)
 100 {
 101         tracing_stop_sched_switch();
 102 }