1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace context switch
4 *
5 * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
6 *
7 */
8#include <linux/module.h>
9#include <linux/kallsyms.h>
10#include <linux/uaccess.h>
11#include <linux/ftrace.h>
12#include <trace/events/sched.h>
13
14#include "trace.h"
15
16#define RECORD_CMDLINE 1
17#define RECORD_TGID 2
18
19static int sched_cmdline_ref;
20static int sched_tgid_ref;
21static DEFINE_MUTEX(sched_register_mutex);
22
23static void
24probe_sched_switch(void *ignore, bool preempt,
25 struct task_struct *prev, struct task_struct *next,
26 unsigned int prev_state)
27{
28 int flags;
29
30 flags = (RECORD_TGID * !!sched_tgid_ref) +
31 (RECORD_CMDLINE * !!sched_cmdline_ref);
32
33 if (!flags)
34 return;
35 tracing_record_taskinfo_sched_switch(prev, next, flags);
36}
37
38static void
39probe_sched_wakeup(void *ignore, struct task_struct *wakee)
40{
41 int flags;
42
43 flags = (RECORD_TGID * !!sched_tgid_ref) +
44 (RECORD_CMDLINE * !!sched_cmdline_ref);
45
46 if (!flags)
47 return;
48 tracing_record_taskinfo_sched_switch(current, next: wakee, flags);
49}
50
51static int tracing_sched_register(void)
52{
53 int ret;
54
55 ret = register_trace_sched_wakeup(probe: probe_sched_wakeup, NULL);
56 if (ret) {
57 pr_info("wakeup trace: Couldn't activate tracepoint"
58 " probe to kernel_sched_wakeup\n");
59 return ret;
60 }
61
62 ret = register_trace_sched_wakeup_new(probe: probe_sched_wakeup, NULL);
63 if (ret) {
64 pr_info("wakeup trace: Couldn't activate tracepoint"
65 " probe to kernel_sched_wakeup_new\n");
66 goto fail_deprobe;
67 }
68
69 ret = register_trace_sched_switch(probe: probe_sched_switch, NULL);
70 if (ret) {
71 pr_info("sched trace: Couldn't activate tracepoint"
72 " probe to kernel_sched_switch\n");
73 goto fail_deprobe_wake_new;
74 }
75
76 return ret;
77fail_deprobe_wake_new:
78 unregister_trace_sched_wakeup_new(probe: probe_sched_wakeup, NULL);
79fail_deprobe:
80 unregister_trace_sched_wakeup(probe: probe_sched_wakeup, NULL);
81 return ret;
82}
83
84static void tracing_sched_unregister(void)
85{
86 unregister_trace_sched_switch(probe: probe_sched_switch, NULL);
87 unregister_trace_sched_wakeup_new(probe: probe_sched_wakeup, NULL);
88 unregister_trace_sched_wakeup(probe: probe_sched_wakeup, NULL);
89}
90
91static void tracing_start_sched_switch(int ops)
92{
93 bool sched_register;
94
95 mutex_lock(&sched_register_mutex);
96 sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
97
98 switch (ops) {
99 case RECORD_CMDLINE:
100 sched_cmdline_ref++;
101 break;
102
103 case RECORD_TGID:
104 sched_tgid_ref++;
105 break;
106 }
107
108 if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
109 tracing_sched_register();
110 mutex_unlock(lock: &sched_register_mutex);
111}
112
113static void tracing_stop_sched_switch(int ops)
114{
115 mutex_lock(&sched_register_mutex);
116
117 switch (ops) {
118 case RECORD_CMDLINE:
119 sched_cmdline_ref--;
120 break;
121
122 case RECORD_TGID:
123 sched_tgid_ref--;
124 break;
125 }
126
127 if (!sched_cmdline_ref && !sched_tgid_ref)
128 tracing_sched_unregister();
129 mutex_unlock(lock: &sched_register_mutex);
130}
131
132void tracing_start_cmdline_record(void)
133{
134 tracing_start_sched_switch(RECORD_CMDLINE);
135}
136
137void tracing_stop_cmdline_record(void)
138{
139 tracing_stop_sched_switch(RECORD_CMDLINE);
140}
141
142void tracing_start_tgid_record(void)
143{
144 tracing_start_sched_switch(RECORD_TGID);
145}
146
147void tracing_stop_tgid_record(void)
148{
149 tracing_stop_sched_switch(RECORD_TGID);
150}
151

source code of linux/kernel/trace/trace_sched_switch.c