Merge git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6
[linux-2.6] / 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         int cpu;
28         int pc;
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         pc = preempt_count();
40         local_irq_save(flags);
41         cpu = raw_smp_processor_id();
42         data = ctx_trace->data[cpu];
43
44         if (likely(!atomic_read(&data->disabled)))
45                 tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
46
47         local_irq_restore(flags);
48 }
49
50 static void
51 probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
52 {
53         struct trace_array_cpu *data;
54         unsigned long flags;
55         int cpu, pc;
56
57         if (!likely(tracer_enabled))
58                 return;
59
60         pc = preempt_count();
61         tracing_record_cmdline(current);
62
63         local_irq_save(flags);
64         cpu = raw_smp_processor_id();
65         data = ctx_trace->data[cpu];
66
67         if (likely(!atomic_read(&data->disabled)))
68                 tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
69                                            flags, pc);
70
71         local_irq_restore(flags);
72 }
73
74 static void sched_switch_reset(struct trace_array *tr)
75 {
76         int cpu;
77
78         tr->time_start = ftrace_now(tr->cpu);
79
80         for_each_online_cpu(cpu)
81                 tracing_reset(tr, cpu);
82 }
83
84 static int tracing_sched_register(void)
85 {
86         int ret;
87
88         ret = register_trace_sched_wakeup(probe_sched_wakeup);
89         if (ret) {
90                 pr_info("wakeup trace: Couldn't activate tracepoint"
91                         " probe to kernel_sched_wakeup\n");
92                 return ret;
93         }
94
95         ret = register_trace_sched_wakeup_new(probe_sched_wakeup);
96         if (ret) {
97                 pr_info("wakeup trace: Couldn't activate tracepoint"
98                         " probe to kernel_sched_wakeup_new\n");
99                 goto fail_deprobe;
100         }
101
102         ret = register_trace_sched_switch(probe_sched_switch);
103         if (ret) {
104                 pr_info("sched trace: Couldn't activate tracepoint"
105                         " probe to kernel_sched_schedule\n");
106                 goto fail_deprobe_wake_new;
107         }
108
109         return ret;
110 fail_deprobe_wake_new:
111         unregister_trace_sched_wakeup_new(probe_sched_wakeup);
112 fail_deprobe:
113         unregister_trace_sched_wakeup(probe_sched_wakeup);
114         return ret;
115 }
116
117 static void tracing_sched_unregister(void)
118 {
119         unregister_trace_sched_switch(probe_sched_switch);
120         unregister_trace_sched_wakeup_new(probe_sched_wakeup);
121         unregister_trace_sched_wakeup(probe_sched_wakeup);
122 }
123
124 static void tracing_start_sched_switch(void)
125 {
126         long ref;
127
128         ref = atomic_inc_return(&sched_ref);
129         if (ref == 1)
130                 tracing_sched_register();
131 }
132
133 static void tracing_stop_sched_switch(void)
134 {
135         long ref;
136
137         ref = atomic_dec_and_test(&sched_ref);
138         if (ref)
139                 tracing_sched_unregister();
140 }
141
142 void tracing_start_cmdline_record(void)
143 {
144         tracing_start_sched_switch();
145 }
146
147 void tracing_stop_cmdline_record(void)
148 {
149         tracing_stop_sched_switch();
150 }
151
152 static void start_sched_trace(struct trace_array *tr)
153 {
154         sched_switch_reset(tr);
155         tracing_start_cmdline_record();
156         tracer_enabled = 1;
157 }
158
159 static void stop_sched_trace(struct trace_array *tr)
160 {
161         tracer_enabled = 0;
162         tracing_stop_cmdline_record();
163 }
164
165 static void sched_switch_trace_init(struct trace_array *tr)
166 {
167         ctx_trace = tr;
168
169         if (tr->ctrl)
170                 start_sched_trace(tr);
171 }
172
173 static void sched_switch_trace_reset(struct trace_array *tr)
174 {
175         if (tr->ctrl)
176                 stop_sched_trace(tr);
177 }
178
179 static void sched_switch_trace_ctrl_update(struct trace_array *tr)
180 {
181         /* When starting a new trace, reset the buffers */
182         if (tr->ctrl)
183                 start_sched_trace(tr);
184         else
185                 stop_sched_trace(tr);
186 }
187
188 static struct tracer sched_switch_trace __read_mostly =
189 {
190         .name           = "sched_switch",
191         .init           = sched_switch_trace_init,
192         .reset          = sched_switch_trace_reset,
193         .ctrl_update    = sched_switch_trace_ctrl_update,
194 #ifdef CONFIG_FTRACE_SELFTEST
195         .selftest    = trace_selftest_startup_sched_switch,
196 #endif
197 };
198
199 __init static int init_sched_switch_trace(void)
200 {
201         int ret = 0;
202
203         if (atomic_read(&sched_ref))
204                 ret = tracing_sched_register();
205         if (ret) {
206                 pr_info("error registering scheduler trace\n");
207                 return ret;
208         }
209         return register_tracer(&sched_switch_trace);
210 }
211 device_initcall(init_sched_switch_trace);