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/sched.h>
  14
  15 #include "trace.h"
  16
  17 static struct trace_array       *ctx_trace;
  18 static int __read_mostly        tracer_enabled;
  19 static atomic_t                 sched_ref;
  20
  21 static void
  22 probe_sched_switch(struct rq *__rq, struct task_struct *prev,
  23                         struct task_struct *next)
  24 {
  25         struct trace_array_cpu *data;
  26         unsigned long flags;
  27         long disabled;
  28         int cpu;
  29
  30         if (!atomic_read(&sched_ref))
  31                 return;
  32
  33         tracing_record_cmdline(prev);
  34         tracing_record_cmdline(next);
  35
  36         if (!tracer_enabled)
  37                 return;
  38
  39         local_irq_save(flags);
  40         cpu = raw_smp_processor_id();
  41         data = ctx_trace->data[cpu];
  42         disabled = atomic_inc_return(&data->disabled);
  43
  44         if (likely(disabled == 1))
  45                 tracing_sched_switch_trace(ctx_trace, data, prev, next, flags);
  46
  47         atomic_dec(&data->disabled);
  48         local_irq_restore(flags);
  49 }
  50
  51 static void
  52 probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
  53 {
  54         struct trace_array_cpu *data;
  55         unsigned long flags;
  56         long disabled;
  57         int cpu;
  58
  59         if (!likely(tracer_enabled))
  60                 return;
  61
  62         tracing_record_cmdline(current);
  63
  64         local_irq_save(flags);
  65         cpu = raw_smp_processor_id();
  66         data = ctx_trace->data[cpu];
  67         disabled = atomic_inc_return(&data->disabled);
  68
  69         if (likely(disabled == 1))
  70                 tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
  71                         flags);
  72
  73         atomic_dec(&data->disabled);
  74         local_irq_restore(flags);
  75 }
  76
  77 static void sched_switch_reset(struct trace_array *tr)
  78 {
  79         int cpu;
  80
  81         tr->time_start = ftrace_now(tr->cpu);
  82
  83         for_each_online_cpu(cpu)
  84                 tracing_reset(tr->data[cpu]);
  85 }
  86
  87 static int tracing_sched_register(void)
  88 {
  89         int ret;
  90
  91         ret = register_trace_sched_wakeup(probe_sched_wakeup);
  92         if (ret) {
  93                 pr_info("wakeup trace: Couldn't activate tracepoint"
  94                         " probe to kernel_sched_wakeup\n");
  95                 return ret;
  96         }
  97
  98         ret = register_trace_sched_wakeup_new(probe_sched_wakeup);
  99         if (ret) {
 100                 pr_info("wakeup trace: Couldn't activate tracepoint"
 101                         " probe to kernel_sched_wakeup_new\n");
 102                 goto fail_deprobe;
 103         }
 104
 105         ret = register_trace_sched_switch(probe_sched_switch);
 106         if (ret) {
 107                 pr_info("sched trace: Couldn't activate tracepoint"
 108                         " probe to kernel_sched_schedule\n");
 109                 goto fail_deprobe_wake_new;
 110         }
 111
 112         return ret;
 113 fail_deprobe_wake_new:
 114         unregister_trace_sched_wakeup_new(probe_sched_wakeup);
 115 fail_deprobe:
 116         unregister_trace_sched_wakeup(probe_sched_wakeup);
 117         return ret;
 118 }
 119
 120 static void tracing_sched_unregister(void)
 121 {
 122         unregister_trace_sched_switch(probe_sched_switch);
 123         unregister_trace_sched_wakeup_new(probe_sched_wakeup);
 124         unregister_trace_sched_wakeup(probe_sched_wakeup);
 125 }
 126
 127 static void tracing_start_sched_switch(void)
 128 {
 129         long ref;
 130
 131         ref = atomic_inc_return(&sched_ref);
 132         if (ref == 1)
 133                 tracing_sched_register();
 134 }
 135
 136 static void tracing_stop_sched_switch(void)
 137 {
 138         long ref;
 139
 140         ref = atomic_dec_and_test(&sched_ref);
 141         if (ref)
 142                 tracing_sched_unregister();
 143 }
 144
 145 void tracing_start_cmdline_record(void)
 146 {
 147         tracing_start_sched_switch();
 148 }
 149
 150 void tracing_stop_cmdline_record(void)
 151 {
 152         tracing_stop_sched_switch();
 153 }
 154
 155 static void start_sched_trace(struct trace_array *tr)
 156 {
 157         sched_switch_reset(tr);
 158         tracing_start_cmdline_record();
 159         tracer_enabled = 1;
 160 }
 161
 162 static void stop_sched_trace(struct trace_array *tr)
 163 {
 164         tracer_enabled = 0;
 165         tracing_stop_cmdline_record();
 166 }
 167
 168 static void sched_switch_trace_init(struct trace_array *tr)
 169 {
 170         ctx_trace = tr;
 171
 172         if (tr->ctrl)
 173                 start_sched_trace(tr);
 174 }
 175
 176 static void sched_switch_trace_reset(struct trace_array *tr)
 177 {
 178         if (tr->ctrl)
 179                 stop_sched_trace(tr);
 180 }
 181
 182 static void sched_switch_trace_ctrl_update(struct trace_array *tr)
 183 {
 184         /* When starting a new trace, reset the buffers */
 185         if (tr->ctrl)
 186                 start_sched_trace(tr);
 187         else
 188                 stop_sched_trace(tr);
 189 }
 190
 191 static struct tracer sched_switch_trace __read_mostly =
 192 {
 193         .name           = "sched_switch",
 194         .init           = sched_switch_trace_init,
 195         .reset          = sched_switch_trace_reset,
 196         .ctrl_update    = sched_switch_trace_ctrl_update,
 197 #ifdef CONFIG_FTRACE_SELFTEST
 198         .selftest    = trace_selftest_startup_sched_switch,
 199 #endif
 200 };
 201
 202 __init static int init_sched_switch_trace(void)
 203 {
 204         int ret = 0;
 205
 206         if (atomic_read(&sched_ref))
 207                 ret = tracing_sched_register();
 208         if (ret) {
 209                 pr_info("error registering scheduler trace\n");
 210                 return ret;
 211         }
 212         return register_tracer(&sched_switch_trace);
 213 }
 214 device_initcall(init_sched_switch_trace);