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Linux/kernel/trace/trace_sched_switch.c

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  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 (!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 (!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 
248 

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