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                    unsigned int prev_state)
  27 {
  28         int flags;
  29
  30         flags = (RECORD_TGID * !!sched_tgid_ref) +
  31                 (RECORD_CMDLINE * !!sched_cmdline_ref);
  32
  33         if (!flags)
  34                 return;
  35         tracing_record_taskinfo_sched_switch(prev, next, flags);
  36 }
  37
  38 static void
  39 probe_sched_wakeup(void *ignore, struct task_struct *wakee)
  40 {
  41         int flags;
  42
  43         flags = (RECORD_TGID * !!sched_tgid_ref) +
  44                 (RECORD_CMDLINE * !!sched_cmdline_ref);
  45
  46         if (!flags)
  47                 return;
  48         tracing_record_taskinfo_sched_switch(current, wakee, flags);
  49 }
  50
  51 static int tracing_sched_register(void)
  52 {
  53         int ret;
  54
  55         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
  56         if (ret) {
  57                 pr_info("wakeup trace: Couldn't activate tracepoint"
  58                         " probe to kernel_sched_wakeup\n");
  59                 return ret;
  60         }
  61
  62         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  63         if (ret) {
  64                 pr_info("wakeup trace: Couldn't activate tracepoint"
  65                         " probe to kernel_sched_wakeup_new\n");
  66                 goto fail_deprobe;
  67         }
  68
  69         ret = register_trace_sched_switch(probe_sched_switch, NULL);
  70         if (ret) {
  71                 pr_info("sched trace: Couldn't activate tracepoint"
  72                         " probe to kernel_sched_switch\n");
  73                 goto fail_deprobe_wake_new;
  74         }
  75
  76         return ret;
  77 fail_deprobe_wake_new:
  78         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  79 fail_deprobe:
  80         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  81         return ret;
  82 }
  83
  84 static void tracing_sched_unregister(void)
  85 {
  86         unregister_trace_sched_switch(probe_sched_switch, NULL);
  87         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  88         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  89 }
  90
  91 static void tracing_start_sched_switch(int ops)
  92 {
  93         bool sched_register;
  94
  95         mutex_lock(&sched_register_mutex);
  96         sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
  97
  98         switch (ops) {
  99         case RECORD_CMDLINE:
 100                 sched_cmdline_ref++;
 101                 break;
 102
 103         case RECORD_TGID:
 104                 sched_tgid_ref++;
 105                 break;
 106         }
 107
 108         if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
 109                 tracing_sched_register();
 110         mutex_unlock(&sched_register_mutex);
 111 }
 112
 113 static void tracing_stop_sched_switch(int ops)
 114 {
 115         mutex_lock(&sched_register_mutex);
 116
 117         switch (ops) {
 118         case RECORD_CMDLINE:
 119                 sched_cmdline_ref--;
 120                 break;
 121
 122         case RECORD_TGID:
 123                 sched_tgid_ref--;
 124                 break;
 125         }
 126
 127         if (!sched_cmdline_ref && !sched_tgid_ref)
 128                 tracing_sched_unregister();
 129         mutex_unlock(&sched_register_mutex);
 130 }
 131
 132 void tracing_start_cmdline_record(void)
 133 {
 134         tracing_start_sched_switch(RECORD_CMDLINE);
 135 }
 136
 137 void tracing_stop_cmdline_record(void)
 138 {
 139         tracing_stop_sched_switch(RECORD_CMDLINE);
 140 }
 141
 142 void tracing_start_tgid_record(void)
 143 {
 144         tracing_start_sched_switch(RECORD_TGID);
 145 }
 146
 147 void tracing_stop_tgid_record(void)
 148 {
 149         tracing_stop_sched_switch(RECORD_TGID);
 150 }