mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-28 07:04:00 +08:00
64ae572bc7
Reading the sched_cmdline_ref and sched_tgid_ref initial state within
tracing_start_sched_switch without holding the sched_register_mutex is
racy against concurrent updates, which can lead to tracepoint probes
being registered more than once (and thus trigger warnings within
tracepoint.c).
[ May be the fix for this bug ]
Link: https://lore.kernel.org/r/000000000000ab6f84056c786b93@google.com
Link: http://lkml.kernel.org/r/20190817141208.15226-1-mathieu.desnoyers@efficios.com
Cc: stable@vger.kernel.org
CC: Steven Rostedt (VMware) <rostedt@goodmis.org>
CC: Joel Fernandes (Google) <joel@joelfernandes.org>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Paul E. McKenney <paulmck@linux.ibm.com>
Reported-by: syzbot+774fddf07b7ab29a1e55@syzkaller.appspotmail.com
Fixes: d914ba37d7 ("tracing: Add support for recording tgid of tasks")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
150 lines
3.1 KiB
C
150 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* trace context switch
|
|
*
|
|
* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
|
|
*
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/ftrace.h>
|
|
#include <trace/events/sched.h>
|
|
|
|
#include "trace.h"
|
|
|
|
#define RECORD_CMDLINE 1
|
|
#define RECORD_TGID 2
|
|
|
|
static int sched_cmdline_ref;
|
|
static int sched_tgid_ref;
|
|
static DEFINE_MUTEX(sched_register_mutex);
|
|
|
|
static void
|
|
probe_sched_switch(void *ignore, bool preempt,
|
|
struct task_struct *prev, struct task_struct *next)
|
|
{
|
|
int flags;
|
|
|
|
flags = (RECORD_TGID * !!sched_tgid_ref) +
|
|
(RECORD_CMDLINE * !!sched_cmdline_ref);
|
|
|
|
if (!flags)
|
|
return;
|
|
tracing_record_taskinfo_sched_switch(prev, next, flags);
|
|
}
|
|
|
|
static void
|
|
probe_sched_wakeup(void *ignore, struct task_struct *wakee)
|
|
{
|
|
int flags;
|
|
|
|
flags = (RECORD_TGID * !!sched_tgid_ref) +
|
|
(RECORD_CMDLINE * !!sched_cmdline_ref);
|
|
|
|
if (!flags)
|
|
return;
|
|
tracing_record_taskinfo(current, flags);
|
|
}
|
|
|
|
static int tracing_sched_register(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup\n");
|
|
return ret;
|
|
}
|
|
|
|
ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup_new\n");
|
|
goto fail_deprobe;
|
|
}
|
|
|
|
ret = register_trace_sched_switch(probe_sched_switch, NULL);
|
|
if (ret) {
|
|
pr_info("sched trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_switch\n");
|
|
goto fail_deprobe_wake_new;
|
|
}
|
|
|
|
return ret;
|
|
fail_deprobe_wake_new:
|
|
unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
|
|
fail_deprobe:
|
|
unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
|
|
return ret;
|
|
}
|
|
|
|
static void tracing_sched_unregister(void)
|
|
{
|
|
unregister_trace_sched_switch(probe_sched_switch, NULL);
|
|
unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
|
|
unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
|
|
}
|
|
|
|
static void tracing_start_sched_switch(int ops)
|
|
{
|
|
bool sched_register;
|
|
|
|
mutex_lock(&sched_register_mutex);
|
|
sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
|
|
|
|
switch (ops) {
|
|
case RECORD_CMDLINE:
|
|
sched_cmdline_ref++;
|
|
break;
|
|
|
|
case RECORD_TGID:
|
|
sched_tgid_ref++;
|
|
break;
|
|
}
|
|
|
|
if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
|
|
tracing_sched_register();
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
static void tracing_stop_sched_switch(int ops)
|
|
{
|
|
mutex_lock(&sched_register_mutex);
|
|
|
|
switch (ops) {
|
|
case RECORD_CMDLINE:
|
|
sched_cmdline_ref--;
|
|
break;
|
|
|
|
case RECORD_TGID:
|
|
sched_tgid_ref--;
|
|
break;
|
|
}
|
|
|
|
if (!sched_cmdline_ref && !sched_tgid_ref)
|
|
tracing_sched_unregister();
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
void tracing_start_cmdline_record(void)
|
|
{
|
|
tracing_start_sched_switch(RECORD_CMDLINE);
|
|
}
|
|
|
|
void tracing_stop_cmdline_record(void)
|
|
{
|
|
tracing_stop_sched_switch(RECORD_CMDLINE);
|
|
}
|
|
|
|
void tracing_start_tgid_record(void)
|
|
{
|
|
tracing_start_sched_switch(RECORD_TGID);
|
|
}
|
|
|
|
void tracing_stop_tgid_record(void)
|
|
{
|
|
tracing_stop_sched_switch(RECORD_TGID);
|
|
}
|