1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
|
/*
* trace context switch
*
* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/marker.h>
#include <linux/ftrace.h>
#include "trace.h"
static struct trace_array *ctx_trace;
static int __read_mostly tracer_enabled;
static atomic_t sched_ref;
static void
sched_switch_func(void *private, void *__rq, struct task_struct *prev,
struct task_struct *next)
{
struct trace_array **ptr = private;
struct trace_array *tr = *ptr;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
tracing_record_cmdline(prev);
tracing_record_cmdline(next);
if (!tracer_enabled)
return;
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_switch_trace(tr, data, prev, next, flags);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static notrace void
sched_switch_callback(void *probe_data, void *call_data,
const char *format, va_list *args)
{
struct task_struct *prev;
struct task_struct *next;
struct rq *__rq;
if (!atomic_read(&sched_ref))
return;
/* skip prev_pid %d next_pid %d prev_state %ld */
(void)va_arg(*args, int);
(void)va_arg(*args, int);
(void)va_arg(*args, long);
__rq = va_arg(*args, typeof(__rq));
prev = va_arg(*args, typeof(prev));
next = va_arg(*args, typeof(next));
/*
* If tracer_switch_func only points to the local
* switch func, it still needs the ptr passed to it.
*/
sched_switch_func(probe_data, __rq, prev, next);
}
static void
wakeup_func(void *private, void *__rq, struct task_struct *wakee, struct
task_struct *curr)
{
struct trace_array **ptr = private;
struct trace_array *tr = *ptr;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
if (!tracer_enabled)
return;
tracing_record_cmdline(curr);
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_wakeup_trace(tr, data, wakee, curr, flags);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static notrace void
wake_up_callback(void *probe_data, void *call_data,
const char *format, va_list *args)
{
struct task_struct *curr;
struct task_struct *task;
struct rq *__rq;
if (likely(!tracer_enabled))
return;
/* Skip pid %d state %ld */
(void)va_arg(*args, int);
(void)va_arg(*args, long);
/* now get the meat: "rq %p task %p rq->curr %p" */
__rq = va_arg(*args, typeof(__rq));
task = va_arg(*args, typeof(task));
curr = va_arg(*args, typeof(curr));
tracing_record_cmdline(task);
tracing_record_cmdline(curr);
wakeup_func(probe_data, __rq, task, curr);
}
static void sched_switch_reset(struct trace_array *tr)
{
int cpu;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
tracing_reset(tr->data[cpu]);
}
static int tracing_sched_register(void)
{
int ret;
ret = marker_probe_register("kernel_sched_wakeup",
"pid %d state %ld ## rq %p task %p rq->curr %p",
wake_up_callback,
&ctx_trace);
if (ret) {
pr_info("wakeup trace: Couldn't add marker"
" probe to kernel_sched_wakeup\n");
return ret;
}
ret = marker_probe_register("kernel_sched_wakeup_new",
"pid %d state %ld ## rq %p task %p rq->curr %p",
wake_up_callback,
&ctx_trace);
if (ret) {
pr_info("wakeup trace: Couldn't add marker"
" probe to kernel_sched_wakeup_new\n");
goto fail_deprobe;
}
ret = marker_probe_register("kernel_sched_schedule",
"prev_pid %d next_pid %d prev_state %ld "
"## rq %p prev %p next %p",
sched_switch_callback,
&ctx_trace);
if (ret) {
pr_info("sched trace: Couldn't add marker"
" probe to kernel_sched_schedule\n");
goto fail_deprobe_wake_new;
}
return ret;
fail_deprobe_wake_new:
marker_probe_unregister("kernel_sched_wakeup_new",
wake_up_callback,
&ctx_trace);
fail_deprobe:
marker_probe_unregister("kernel_sched_wakeup",
wake_up_callback,
&ctx_trace);
return ret;
}
static void tracing_sched_unregister(void)
{
marker_probe_unregister("kernel_sched_schedule",
sched_switch_callback,
&ctx_trace);
marker_probe_unregister("kernel_sched_wakeup_new",
wake_up_callback,
&ctx_trace);
marker_probe_unregister("kernel_sched_wakeup",
wake_up_callback,
&ctx_trace);
}
static void tracing_start_sched_switch(void)
{
long ref;
ref = atomic_inc_return(&sched_ref);
if (ref == 1)
tracing_sched_register();
}
static void tracing_stop_sched_switch(void)
{
long ref;
ref = atomic_dec_and_test(&sched_ref);
if (ref)
tracing_sched_unregister();
}
void tracing_start_cmdline_record(void)
{
tracing_start_sched_switch();
}
void tracing_stop_cmdline_record(void)
{
tracing_stop_sched_switch();
}
static void start_sched_trace(struct trace_array *tr)
{
sched_switch_reset(tr);
tracing_start_cmdline_record();
tracer_enabled = 1;
}
static void stop_sched_trace(struct trace_array *tr)
{
tracer_enabled = 0;
tracing_stop_cmdline_record();
}
static void sched_switch_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
if (tr->ctrl)
start_sched_trace(tr);
}
static void sched_switch_trace_reset(struct trace_array *tr)
{
if (tr->ctrl)
stop_sched_trace(tr);
}
static void sched_switch_trace_ctrl_update(struct trace_array *tr)
{
/* When starting a new trace, reset the buffers */
if (tr->ctrl)
start_sched_trace(tr);
else
stop_sched_trace(tr);
}
static struct tracer sched_switch_trace __read_mostly =
{
.name = "sched_switch",
.init = sched_switch_trace_init,
.reset = sched_switch_trace_reset,
.ctrl_update = sched_switch_trace_ctrl_update,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_sched_switch,
#endif
};
__init static int init_sched_switch_trace(void)
{
int ret = 0;
if (atomic_read(&sched_ref))
ret = tracing_sched_register();
if (ret) {
pr_info("error registering scheduler trace\n");
return ret;
}
return register_tracer(&sched_switch_trace);
}
device_initcall(init_sched_switch_trace);
|