4 * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
7 #include <linux/module.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>
17 static struct trace_array *ctx_trace;
18 static int __read_mostly tracer_enabled;
20 static DEFINE_MUTEX(sched_register_mutex);
23 probe_sched_switch(struct rq *__rq, struct task_struct *prev,
24 struct task_struct *next)
26 struct trace_array_cpu *data;
34 tracing_record_cmdline(prev);
35 tracing_record_cmdline(next);
41 local_irq_save(flags);
42 cpu = raw_smp_processor_id();
43 data = ctx_trace->data[cpu];
45 if (likely(!atomic_read(&data->disabled)))
46 tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
48 local_irq_restore(flags);
52 probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
54 struct trace_array_cpu *data;
58 if (!likely(tracer_enabled))
62 tracing_record_cmdline(current);
64 local_irq_save(flags);
65 cpu = raw_smp_processor_id();
66 data = ctx_trace->data[cpu];
68 if (likely(!atomic_read(&data->disabled)))
69 tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
72 local_irq_restore(flags);
75 static void sched_switch_reset(struct trace_array *tr)
79 tr->time_start = ftrace_now(tr->cpu);
81 for_each_online_cpu(cpu)
82 tracing_reset(tr, cpu);
85 static int tracing_sched_register(void)
89 ret = register_trace_sched_wakeup(probe_sched_wakeup);
91 pr_info("wakeup trace: Couldn't activate tracepoint"
92 " probe to kernel_sched_wakeup\n");
96 ret = register_trace_sched_wakeup_new(probe_sched_wakeup);
98 pr_info("wakeup trace: Couldn't activate tracepoint"
99 " probe to kernel_sched_wakeup_new\n");
103 ret = register_trace_sched_switch(probe_sched_switch);
105 pr_info("sched trace: Couldn't activate tracepoint"
106 " probe to kernel_sched_schedule\n");
107 goto fail_deprobe_wake_new;
111 fail_deprobe_wake_new:
112 unregister_trace_sched_wakeup_new(probe_sched_wakeup);
114 unregister_trace_sched_wakeup(probe_sched_wakeup);
118 static void tracing_sched_unregister(void)
120 unregister_trace_sched_switch(probe_sched_switch);
121 unregister_trace_sched_wakeup_new(probe_sched_wakeup);
122 unregister_trace_sched_wakeup(probe_sched_wakeup);
125 static void tracing_start_sched_switch(void)
127 mutex_lock(&sched_register_mutex);
128 if (!(sched_ref++)) {
130 tracing_sched_register();
132 mutex_unlock(&sched_register_mutex);
135 static void tracing_stop_sched_switch(void)
137 mutex_lock(&sched_register_mutex);
138 if (!(--sched_ref)) {
139 tracing_sched_unregister();
142 mutex_unlock(&sched_register_mutex);
145 void tracing_start_cmdline_record(void)
147 tracing_start_sched_switch();
150 void tracing_stop_cmdline_record(void)
152 tracing_stop_sched_switch();
156 * tracing_cmdline_assign_trace - assign a trace array for ctx switch
157 * @tr: trace array pointer to assign
159 * Some tracers might want to record the context switches in their
160 * trace. This function lets those tracers assign the trace array
163 void tracing_cmdline_assign_trace(struct trace_array *tr)
168 static void start_sched_trace(struct trace_array *tr)
170 sched_switch_reset(tr);
171 tracing_start_cmdline_record();
174 static void stop_sched_trace(struct trace_array *tr)
176 tracing_stop_cmdline_record();
179 static void sched_switch_trace_init(struct trace_array *tr)
184 start_sched_trace(tr);
187 static void sched_switch_trace_reset(struct trace_array *tr)
189 if (tr->ctrl && sched_ref)
190 stop_sched_trace(tr);
193 static void sched_switch_trace_ctrl_update(struct trace_array *tr)
195 /* When starting a new trace, reset the buffers */
197 start_sched_trace(tr);
199 stop_sched_trace(tr);
202 static void sched_switch_trace_start(struct trace_array *tr)
204 sched_switch_reset(tr);
205 tracing_start_sched_switch();
208 static void sched_switch_trace_stop(struct trace_array *tr)
210 tracing_stop_sched_switch();
213 static struct tracer sched_switch_trace __read_mostly =
215 .name = "sched_switch",
216 .init = sched_switch_trace_init,
217 .reset = sched_switch_trace_reset,
218 .start = sched_switch_trace_start,
219 .stop = sched_switch_trace_stop,
220 .ctrl_update = sched_switch_trace_ctrl_update,
221 #ifdef CONFIG_FTRACE_SELFTEST
222 .selftest = trace_selftest_startup_sched_switch,
226 __init static int init_sched_switch_trace(void)
228 return register_tracer(&sched_switch_trace);
230 device_initcall(init_sched_switch_trace);