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/events/sched.h>
  14
  15 #include "trace.h"
  16
  17 static struct trace_array       *ctx_trace;
  18 static int __read_mostly        tracer_enabled;
  19 static int                      sched_ref;
  20 static DEFINE_MUTEX(sched_register_mutex);
  21 static int                      sched_stopped;
  22
  23
  24 void
  25 tracing_sched_switch_trace(struct trace_array *tr,
  26                            struct task_struct *prev,
  27                            struct task_struct *next,
  28                            unsigned long flags, int pc)
  29 {
  30         struct ftrace_event_call *call = &event_context_switch;
  31         struct ring_buffer *buffer = tr->trace_buffer.buffer;
  32         struct ring_buffer_event *event;
  33         struct ctx_switch_entry *entry;
  34
  35         event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
  36                                           sizeof(*entry), flags, pc);
  37         if (!event)
  38                 return;
  39         entry   = ring_buffer_event_data(event);
  40         entry->prev_pid                 = prev->pid;
  41         entry->prev_prio                = prev->prio;
  42         entry->prev_state               = prev->state;
  43         entry->next_pid                 = next->pid;
  44         entry->next_prio                = next->prio;
  45         entry->next_state               = next->state;
  46         entry->next_cpu = task_cpu(next);
  47
  48         if (!call_filter_check_discard(call, entry, buffer, event))
  49                 trace_buffer_unlock_commit(buffer, event, flags, pc);
  50 }
  51
  52 static void
  53 probe_sched_switch(void *ignore, struct task_struct *prev, struct task_struct *next)
  54 {
  55         struct trace_array_cpu *data;
  56         unsigned long flags;
  57         int cpu;
  58         int pc;
  59
  60         if (unlikely(!sched_ref))
  61                 return;
  62
  63         tracing_record_cmdline(prev);
  64         tracing_record_cmdline(next);
  65
  66         if (!tracer_enabled || sched_stopped)
  67                 return;
  68
  69         pc = preempt_count();
  70         local_irq_save(flags);
  71         cpu = raw_smp_processor_id();
  72         data = per_cpu_ptr(ctx_trace->trace_buffer.data, cpu);
  73
  74         if (likely(!atomic_read(&data->disabled)))
  75                 tracing_sched_switch_trace(ctx_trace, prev, next, flags, pc);
  76
  77         local_irq_restore(flags);
  78 }
  79
  80 void
  81 tracing_sched_wakeup_trace(struct trace_array *tr,
  82                            struct task_struct *wakee,
  83                            struct task_struct *curr,
  84                            unsigned long flags, int pc)
  85 {
  86         struct ftrace_event_call *call = &event_wakeup;
  87         struct ring_buffer_event *event;
  88         struct ctx_switch_entry *entry;
  89         struct ring_buffer *buffer = tr->trace_buffer.buffer;
  90
  91         event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
  92                                           sizeof(*entry), flags, pc);
  93         if (!event)
  94                 return;
  95         entry   = ring_buffer_event_data(event);
  96         entry->prev_pid                 = curr->pid;
  97         entry->prev_prio                = curr->prio;
  98         entry->prev_state               = curr->state;
  99         entry->next_pid                 = wakee->pid;
 100         entry->next_prio                = wakee->prio;
 101         entry->next_state               = wakee->state;
 102         entry->next_cpu                 = task_cpu(wakee);
 103
 104         if (!call_filter_check_discard(call, entry, buffer, event))
 105                 trace_buffer_unlock_commit(buffer, event, flags, pc);
 106 }
 107
 108 static void
 109 probe_sched_wakeup(void *ignore, struct task_struct *wakee, int success)
 110 {
 111         struct trace_array_cpu *data;
 112         unsigned long flags;
 113         int cpu, pc;
 114
 115         if (unlikely(!sched_ref))
 116                 return;
 117
 118         tracing_record_cmdline(current);
 119
 120         if (!tracer_enabled || sched_stopped)
 121                 return;
 122
 123         pc = preempt_count();
 124         local_irq_save(flags);
 125         cpu = raw_smp_processor_id();
 126         data = per_cpu_ptr(ctx_trace->trace_buffer.data, cpu);
 127
 128         if (likely(!atomic_read(&data->disabled)))
 129                 tracing_sched_wakeup_trace(ctx_trace, wakee, current,
 130                                            flags, pc);
 131
 132         local_irq_restore(flags);
 133 }
 134
 135 static int tracing_sched_register(void)
 136 {
 137         int ret;
 138
 139         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
 140         if (ret) {
 141                 pr_info("wakeup trace: Couldn't activate tracepoint"
 142                         " probe to kernel_sched_wakeup\n");
 143                 return ret;
 144         }
 145
 146         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
 147         if (ret) {
 148                 pr_info("wakeup trace: Couldn't activate tracepoint"
 149                         " probe to kernel_sched_wakeup_new\n");
 150                 goto fail_deprobe;
 151         }
 152
 153         ret = register_trace_sched_switch(probe_sched_switch, NULL);
 154         if (ret) {
 155                 pr_info("sched trace: Couldn't activate tracepoint"
 156                         " probe to kernel_sched_switch\n");
 157                 goto fail_deprobe_wake_new;
 158         }
 159
 160         return ret;
 161 fail_deprobe_wake_new:
 162         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
 163 fail_deprobe:
 164         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
 165         return ret;
 166 }
 167
 168 static void tracing_sched_unregister(void)
 169 {
 170         unregister_trace_sched_switch(probe_sched_switch, NULL);
 171         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
 172         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
 173 }
 174
 175 static void tracing_start_sched_switch(void)
 176 {
 177         mutex_lock(&sched_register_mutex);
 178         if (!(sched_ref++))
 179                 tracing_sched_register();
 180         mutex_unlock(&sched_register_mutex);
 181 }
 182
 183 static void tracing_stop_sched_switch(void)
 184 {
 185         mutex_lock(&sched_register_mutex);
 186         if (!(--sched_ref))
 187                 tracing_sched_unregister();
 188         mutex_unlock(&sched_register_mutex);
 189 }
 190
 191 void tracing_start_cmdline_record(void)
 192 {
 193         tracing_start_sched_switch();
 194 }
 195
 196 void tracing_stop_cmdline_record(void)
 197 {
 198         tracing_stop_sched_switch();
 199 }
 200
 201 /**
 202  * tracing_start_sched_switch_record - start tracing context switches
 203  *
 204  * Turns on context switch tracing for a tracer.
 205  */
 206 void tracing_start_sched_switch_record(void)
 207 {
 208         if (unlikely(!ctx_trace)) {
 209                 WARN_ON(1);
 210                 return;
 211         }
 212
 213         tracing_start_sched_switch();
 214
 215         mutex_lock(&sched_register_mutex);
 216         tracer_enabled++;
 217         mutex_unlock(&sched_register_mutex);
 218 }
 219
 220 /**
 221  * tracing_stop_sched_switch_record - start tracing context switches
 222  *
 223  * Turns off context switch tracing for a tracer.
 224  */
 225 void tracing_stop_sched_switch_record(void)
 226 {
 227         mutex_lock(&sched_register_mutex);
 228         tracer_enabled--;
 229         WARN_ON(tracer_enabled < 0);
 230         mutex_unlock(&sched_register_mutex);
 231
 232         tracing_stop_sched_switch();
 233 }
 234
 235 /**
 236  * tracing_sched_switch_assign_trace - assign a trace array for ctx switch
 237  * @tr: trace array pointer to assign
 238  *
 239  * Some tracers might want to record the context switches in their
 240  * trace. This function lets those tracers assign the trace array
 241  * to use.
 242  */
 243 void tracing_sched_switch_assign_trace(struct trace_array *tr)
 244 {
 245         ctx_trace = tr;
 246 }
 247