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/marker.h>
  13 #include <linux/ftrace.h>
  14
  15 #include "trace.h"
  16
  17 static struct trace_array       *ctx_trace;
  18 static int __read_mostly        tracer_enabled;
  19
  20 static void
  21 ctx_switch_func(void *__rq, struct task_struct *prev, struct task_struct *next)
  22 {
  23         struct trace_array *tr = ctx_trace;
  24         struct trace_array_cpu *data;
  25         unsigned long flags;
  26         long disabled;
  27         int cpu;
  28
  29         if (!tracer_enabled)
  30                 return;
  31
  32         tracing_record_cmdline(prev);
  33
  34         local_irq_save(flags);
  35         cpu = raw_smp_processor_id();
  36         data = tr->data[cpu];
  37         disabled = atomic_inc_return(&data->disabled);
  38
  39         if (likely(disabled == 1))
  40                 tracing_sched_switch_trace(tr, data, prev, next, flags);
  41
  42         atomic_dec(&data->disabled);
  43         local_irq_restore(flags);
  44 }
  45
  46 static void
  47 wakeup_func(void *__rq, struct task_struct *wakee, struct task_struct *curr)
  48 {
  49         struct trace_array *tr = ctx_trace;
  50         struct trace_array_cpu *data;
  51         unsigned long flags;
  52         long disabled;
  53         int cpu;
  54
  55         if (!tracer_enabled)
  56                 return;
  57
  58         tracing_record_cmdline(curr);
  59
  60         local_irq_save(flags);
  61         cpu = raw_smp_processor_id();
  62         data = tr->data[cpu];
  63         disabled = atomic_inc_return(&data->disabled);
  64
  65         if (likely(disabled == 1))
  66                 tracing_sched_wakeup_trace(tr, data, wakee, curr, flags);
  67
  68         atomic_dec(&data->disabled);
  69         local_irq_restore(flags);
  70 }
  71
  72 void
  73 ftrace_ctx_switch(void *__rq, struct task_struct *prev,
  74                   struct task_struct *next)
  75 {
  76         /*
  77          * If tracer_switch_func only points to the local
  78          * switch func, it still needs the ptr passed to it.
  79          */
  80         ctx_switch_func(__rq, prev, next);
  81
  82         /*
  83          * Chain to the wakeup tracer (this is a NOP if disabled):
  84          */
  85         wakeup_sched_switch(prev, next);
  86 }
  87
  88 void
  89 ftrace_wake_up_task(void *__rq, struct task_struct *wakee,
  90                     struct task_struct *curr)
  91 {
  92         wakeup_func(__rq, wakee, curr);
  93
  94         /*
  95          * Chain to the wakeup tracer (this is a NOP if disabled):
  96          */
  97         wakeup_sched_wakeup(wakee, curr);
  98 }
  99
 100 void
 101 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
 102 {
 103         struct trace_array *tr = ctx_trace;
 104         struct trace_array_cpu *data;
 105         unsigned long flags;
 106         long disabled;
 107         int cpu;
 108
 109         if (!tracer_enabled)
 110                 return;
 111
 112         local_irq_save(flags);
 113         cpu = raw_smp_processor_id();
 114         data = tr->data[cpu];
 115         disabled = atomic_inc_return(&data->disabled);
 116
 117         if (likely(disabled == 1))
 118                 __trace_special(tr, data, arg1, arg2, arg3);
 119
 120         atomic_dec(&data->disabled);
 121         local_irq_restore(flags);
 122 }
 123
 124 static void sched_switch_reset(struct trace_array *tr)
 125 {
 126         int cpu;
 127
 128         tr->time_start = ftrace_now(tr->cpu);
 129
 130         for_each_online_cpu(cpu)
 131                 tracing_reset(tr->data[cpu]);
 132 }
 133
 134 static void start_sched_trace(struct trace_array *tr)
 135 {
 136         sched_switch_reset(tr);
 137         tracer_enabled = 1;
 138 }
 139
 140 static void stop_sched_trace(struct trace_array *tr)
 141 {
 142         tracer_enabled = 0;
 143 }
 144
 145 static void sched_switch_trace_init(struct trace_array *tr)
 146 {
 147         ctx_trace = tr;
 148
 149         if (tr->ctrl)
 150                 start_sched_trace(tr);
 151 }
 152
 153 static void sched_switch_trace_reset(struct trace_array *tr)
 154 {
 155         if (tr->ctrl)
 156                 stop_sched_trace(tr);
 157 }
 158
 159 static void sched_switch_trace_ctrl_update(struct trace_array *tr)
 160 {
 161         /* When starting a new trace, reset the buffers */
 162         if (tr->ctrl)
 163                 start_sched_trace(tr);
 164         else
 165                 stop_sched_trace(tr);
 166 }
 167
 168 static struct tracer sched_switch_trace __read_mostly =
 169 {
 170         .name           = "sched_switch",
 171         .init           = sched_switch_trace_init,
 172         .reset          = sched_switch_trace_reset,
 173         .ctrl_update    = sched_switch_trace_ctrl_update,
 174 #ifdef CONFIG_FTRACE_SELFTEST
 175         .selftest    = trace_selftest_startup_sched_switch,
 176 #endif
 177 };
 178
 179 __init static int init_sched_switch_trace(void)
 180 {
 181         return register_tracer(&sched_switch_trace);
 182 }
 183 device_initcall(init_sched_switch_trace);