kernel/trace/trace_sched_switch.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * trace context switch
0004  *
0005  * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
0006  *
0007  */
0008 #include <linux/module.h>
0009 #include <linux/kallsyms.h>
0010 #include <linux/uaccess.h>
0011 #include <linux/ftrace.h>
0012 #include <trace/events/sched.h>
0013
0014 #include "trace.h"
0015
0016 #define RECORD_CMDLINE  1
0017 #define RECORD_TGID 2
0018
0019 static int      sched_cmdline_ref;
0020 static int      sched_tgid_ref;
0021 static DEFINE_MUTEX(sched_register_mutex);
0022
0023 static void
0024 probe_sched_switch(void *ignore, bool preempt,
0025            struct task_struct *prev, struct task_struct *next,
0026            unsigned int prev_state)
0027 {
0028     int flags;
0029
0030     flags = (RECORD_TGID * !!sched_tgid_ref) +
0031         (RECORD_CMDLINE * !!sched_cmdline_ref);
0032
0033     if (!flags)
0034         return;
0035     tracing_record_taskinfo_sched_switch(prev, next, flags);
0036 }
0037
0038 static void
0039 probe_sched_wakeup(void *ignore, struct task_struct *wakee)
0040 {
0041     int flags;
0042
0043     flags = (RECORD_TGID * !!sched_tgid_ref) +
0044         (RECORD_CMDLINE * !!sched_cmdline_ref);
0045
0046     if (!flags)
0047         return;
0048     tracing_record_taskinfo_sched_switch(current, wakee, flags);
0049 }
0050
0051 static int tracing_sched_register(void)
0052 {
0053     int ret;
0054
0055     ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
0056     if (ret) {
0057         pr_info("wakeup trace: Couldn't activate tracepoint"
0058             " probe to kernel_sched_wakeup\n");
0059         return ret;
0060     }
0061
0062     ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
0063     if (ret) {
0064         pr_info("wakeup trace: Couldn't activate tracepoint"
0065             " probe to kernel_sched_wakeup_new\n");
0066         goto fail_deprobe;
0067     }
0068
0069     ret = register_trace_sched_switch(probe_sched_switch, NULL);
0070     if (ret) {
0071         pr_info("sched trace: Couldn't activate tracepoint"
0072             " probe to kernel_sched_switch\n");
0073         goto fail_deprobe_wake_new;
0074     }
0075
0076     return ret;
0077 fail_deprobe_wake_new:
0078     unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
0079 fail_deprobe:
0080     unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
0081     return ret;
0082 }
0083
0084 static void tracing_sched_unregister(void)
0085 {
0086     unregister_trace_sched_switch(probe_sched_switch, NULL);
0087     unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
0088     unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
0089 }
0090
0091 static void tracing_start_sched_switch(int ops)
0092 {
0093     bool sched_register;
0094
0095     mutex_lock(&sched_register_mutex);
0096     sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
0097
0098     switch (ops) {
0099     case RECORD_CMDLINE:
0100         sched_cmdline_ref++;
0101         break;
0102
0103     case RECORD_TGID:
0104         sched_tgid_ref++;
0105         break;
0106     }
0107
0108     if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
0109         tracing_sched_register();
0110     mutex_unlock(&sched_register_mutex);
0111 }
0112
0113 static void tracing_stop_sched_switch(int ops)
0114 {
0115     mutex_lock(&sched_register_mutex);
0116
0117     switch (ops) {
0118     case RECORD_CMDLINE:
0119         sched_cmdline_ref--;
0120         break;
0121
0122     case RECORD_TGID:
0123         sched_tgid_ref--;
0124         break;
0125     }
0126
0127     if (!sched_cmdline_ref && !sched_tgid_ref)
0128         tracing_sched_unregister();
0129     mutex_unlock(&sched_register_mutex);
0130 }
0131
0132 void tracing_start_cmdline_record(void)
0133 {
0134     tracing_start_sched_switch(RECORD_CMDLINE);
0135 }
0136
0137 void tracing_stop_cmdline_record(void)
0138 {
0139     tracing_stop_sched_switch(RECORD_CMDLINE);
0140 }
0141
0142 void tracing_start_tgid_record(void)
0143 {
0144     tracing_start_sched_switch(RECORD_TGID);
0145 }
0146
0147 void tracing_stop_tgid_record(void)
0148 {
0149     tracing_stop_sched_switch(RECORD_TGID);
0150 }