kernel/trace/trace_sched_switch.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * trace context switch
   4  *
   5  * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
   6  *
   7  */
   8 #include <linux/module.h>
   9 #include <linux/kallsyms.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/ftrace.h>
  12 #include <trace/events/sched.h>
  13
  14 #include "trace.h"
  15
  16 #define RECORD_CMDLINE  1
  17 #define RECORD_TGID     2
  18
  19 static int              sched_cmdline_ref;
  20 static int              sched_tgid_ref;
  21 static DEFINE_MUTEX(sched_register_mutex);
  22
  23 static void
  24 probe_sched_switch(void *ignore, bool preempt,
  25                    struct task_struct *prev, struct task_struct *next)
  26 {
  27         int flags;
  28
  29         flags = (RECORD_TGID * !!sched_tgid_ref) +
  30                 (RECORD_CMDLINE * !!sched_cmdline_ref);
  31
  32         if (!flags)
  33                 return;
  34         tracing_record_taskinfo_sched_switch(prev, next, flags);
  35 }
  36
  37 static void
  38 probe_sched_wakeup(void *ignore, struct task_struct *wakee)
  39 {
  40         int flags;
  41
  42         flags = (RECORD_TGID * !!sched_tgid_ref) +
  43                 (RECORD_CMDLINE * !!sched_cmdline_ref);
  44
  45         if (!flags)
  46                 return;
  47         tracing_record_taskinfo(current, flags);
  48 }
  49
  50 static int tracing_sched_register(void)
  51 {
  52         int ret;
  53
  54         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
  55         if (ret) {
  56                 pr_info("wakeup trace: Couldn't activate tracepoint"
  57                         " probe to kernel_sched_wakeup\n");
  58                 return ret;
  59         }
  60
  61         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  62         if (ret) {
  63                 pr_info("wakeup trace: Couldn't activate tracepoint"
  64                         " probe to kernel_sched_wakeup_new\n");
  65                 goto fail_deprobe;
  66         }
  67
  68         ret = register_trace_sched_switch(probe_sched_switch, NULL);
  69         if (ret) {
  70                 pr_info("sched trace: Couldn't activate tracepoint"
  71                         " probe to kernel_sched_switch\n");
  72                 goto fail_deprobe_wake_new;
  73         }
  74
  75         return ret;
  76 fail_deprobe_wake_new:
  77         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  78 fail_deprobe:
  79         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  80         return ret;
  81 }
  82
  83 static void tracing_sched_unregister(void)
  84 {
  85         unregister_trace_sched_switch(probe_sched_switch, NULL);
  86         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  87         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  88 }
  89
  90 static void tracing_start_sched_switch(int ops)
  91 {
  92         bool sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
  93         mutex_lock(&sched_register_mutex);
  94
  95         switch (ops) {
  96         case RECORD_CMDLINE:
  97                 sched_cmdline_ref++;
  98                 break;
  99
 100         case RECORD_TGID:
 101                 sched_tgid_ref++;
 102                 break;
 103         }
 104
 105         if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
 106                 tracing_sched_register();
 107         mutex_unlock(&sched_register_mutex);
 108 }
 109
 110 static void tracing_stop_sched_switch(int ops)
 111 {
 112         mutex_lock(&sched_register_mutex);
 113
 114         switch (ops) {
 115         case RECORD_CMDLINE:
 116                 sched_cmdline_ref--;
 117                 break;
 118
 119         case RECORD_TGID:
 120                 sched_tgid_ref--;
 121                 break;
 122         }
 123
 124         if (!sched_cmdline_ref && !sched_tgid_ref)
 125                 tracing_sched_unregister();
 126         mutex_unlock(&sched_register_mutex);
 127 }
 128
 129 void tracing_start_cmdline_record(void)
 130 {
 131         tracing_start_sched_switch(RECORD_CMDLINE);
 132 }
 133
 134 void tracing_stop_cmdline_record(void)
 135 {
 136         tracing_stop_sched_switch(RECORD_CMDLINE);
 137 }
 138
 139 void tracing_start_tgid_record(void)
 140 {
 141         tracing_start_sched_switch(RECORD_TGID);
 142 }
 143
 144 void tracing_stop_tgid_record(void)
 145 {
 146         tracing_stop_sched_switch(RECORD_TGID);
 147 }