* Re: Possible deadlock errors in tools/perf/builtin-sched.c
[not found] <CAAo+4rXNLdgvAiT2-B8cWtLNPnWoGo9RWMW=8SPchzRgxJ4BhA@mail.gmail.com>
@ 2021-08-28 8:06 ` 叶澄锋
2021-08-31 18:46 ` Jiri Olsa
1 sibling, 0 replies; 3+ messages in thread
From: 叶澄锋 @ 2021-08-28 8:06 UTC (permalink / raw)
To: peterz, mingo, acme
Cc: mark.rutland, alexander.shishkin, jolsa, namhyung,
linux-perf-users, linux-kernel, CAI Yuandao
Dear developers:
Thank you for your checking.
It seems there are two deadlock errors on the
locksched->work_done_wait_mutexandsched->start_work_mutex.
They are triggered due to one thread(A) runs function run_one_test
locating in a loop and unreleasing the two locks in
thewait_for_tasksfunction, and another thread(B) runs function
thread_func acquiring the two locks.
Because the two locks are not properly released in thread A, there
will be a deadlock problem if thread B acquires the two locks.
The related codes are below:
Thread A:
static void create_tasks(struct perf_sched *sched)
{
...;
err = pthread_mutex_lock(&sched->start_work_mutex);
...;
err = pthread_mutex_lock(&sched->work_done_wait_mutex);
...;
}
static int perf_sched__replay(struct perf_sched *sched)
{
...;
create_tasks(sched);
printf("------------------------------------------------------------\n");
for (i = 0; i < sched->replay_repeat; i++)
run_one_test(sched); // multiple reacquisition on the lock
sched->work_done_wait_mutex and sched->start_work_mutex
return 0;
}
static void run_one_test(struct perf_sched *sched)
{
...;
wait_for_tasks(sched);
...;
}
static void wait_for_tasks(struct perf_sched *sched)
{
...;
pthread_mutex_unlock(&sched->work_done_wait_mutex);
...;
ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
...;
pthread_mutex_unlock(&sched->start_work_mutex);
...;
ret = pthread_mutex_lock(&sched->start_work_mutex);
....;
}
Thread B:
static void *thread_func(void *ctx)
{
...;
ret = pthread_mutex_lock(&sched->start_work_mutex);
...;
ret = pthread_mutex_unlock(&sched->start_work_mutex);
...;
ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
...;
ret = pthread_mutex_unlock(&sched->work_done_wait_mutex);
..;
}
PS: The previous email fails to reach the maillist, so I send it again.
Thanks,
叶澄锋 <dg573847474@gmail.com> 于2021年8月28日周六 下午3:57写道:
>
> Dear developers:
>
> Thank you for your checking.
>
> It seems there are two deadlock errors on the locksched->work_done_wait_mutexandsched->start_work_mutex.
>
> They are triggered due to one thread(A) runs function run_one_test locating in a loop and unreleasing the two locks in thewait_for_tasksfunction, and another thread(B) runs function thread_func acquiring the two locks.
>
> Because the two locks are not properly released in thread A, there will be a deadlock problem if thread B acquires the two locks.
>
> The related codes are below:
>
> Thread A:
>
> static void create_tasks(struct perf_sched *sched)
> {
> ...;
> err = pthread_mutex_lock(&sched->start_work_mutex);
> ...;
> err = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> }
> static int perf_sched__replay(struct perf_sched *sched)
> {
> ...;
>
> create_tasks(sched);
> printf("------------------------------------------------------------\n");
> for (i = 0; i < sched->replay_repeat; i++)
> run_one_test(sched); // multiple reacquisition on the lock sched->work_done_wait_mutex and sched->start_work_mutex
>
> return 0;
> }
>
> static void run_one_test(struct perf_sched *sched)
> {
> ...;
> wait_for_tasks(sched);
> ...;
> }
> static void wait_for_tasks(struct perf_sched *sched)
> {
> ...;
> pthread_mutex_unlock(&sched->work_done_wait_mutex);
>
> ...;
> ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> pthread_mutex_unlock(&sched->start_work_mutex);
>
> ...;
>
> ret = pthread_mutex_lock(&sched->start_work_mutex);
> ....;
> }
>
> Thread B:
>
> static void *thread_func(void *ctx)
> {
>
> ...;
> ret = pthread_mutex_lock(&sched->start_work_mutex);
> ...;
> ret = pthread_mutex_unlock(&sched->start_work_mutex);
>
> ...;
>
> ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> ret = pthread_mutex_unlock(&sched->work_done_wait_mutex);
> ..;
>
> }
>
>
> Thanks,
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Possible deadlock errors in tools/perf/builtin-sched.c
[not found] <CAAo+4rXNLdgvAiT2-B8cWtLNPnWoGo9RWMW=8SPchzRgxJ4BhA@mail.gmail.com>
2021-08-28 8:06 ` Possible deadlock errors in tools/perf/builtin-sched.c 叶澄锋
@ 2021-08-31 18:46 ` Jiri Olsa
2021-09-01 5:19 ` CAI Yuandao
1 sibling, 1 reply; 3+ messages in thread
From: Jiri Olsa @ 2021-08-31 18:46 UTC (permalink / raw)
To: 叶澄锋
Cc: peterz, mingo, acme, mark.rutland, alexander.shishkin, namhyung,
linux-perf-users, linux-kernel, CAI Yuandao
On Sat, Aug 28, 2021 at 03:57:17PM +0800, 叶澄锋 wrote:
> Dear developers:
>
> Thank you for your checking.
>
> It seems there are two deadlock errors on the lock
> *sched->work_done_wait_mutex*and*sched->start_work_mutex.*
>
> They are triggered due to one thread(A) runs function *run_one_test* locating
> in a loop and unreleasing the two locks in the*wait_for_tasks*function, and
> another thread(B) runs function *thread_func *acquiring the two locks.
>
> Because the two locks are not properly released in thread A, there will be
> a deadlock problem if thread B acquires the two locks.
hi,
do you have a way to reproduce this?
thanks,
jirka
>
> The related codes are below:
>
> Thread A:
>
> static void create_tasks(struct perf_sched *sched)
> {
> ...;
> err = pthread_mutex_lock(&sched->start_work_mutex);
> ...;
> err = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> }
> static int perf_sched__replay(struct perf_sched *sched)
> {
> ...;
>
> create_tasks(sched);
> printf("------------------------------------------------------------\n");
> for (i = 0; i < sched->replay_repeat; i++)
> run_one_test(sched); // multiple reacquisition on the lock
> sched->work_done_wait_mutex and sched->start_work_mutex
>
> return 0;
> }
>
> static void run_one_test(struct perf_sched *sched)
> {
> ...;
> wait_for_tasks(sched);
> ...;
> }
> static void wait_for_tasks(struct perf_sched *sched)
> {
> ...;
> pthread_mutex_unlock(&sched->work_done_wait_mutex);
>
> ...;
> ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> pthread_mutex_unlock(&sched->start_work_mutex);
>
> ...;
>
> ret = pthread_mutex_lock(&sched->start_work_mutex);
> ....;
> }
>
> Thread B:
>
> static void *thread_func(void *ctx)
> {
>
> ...;
> ret = pthread_mutex_lock(&sched->start_work_mutex);
> ...;
> ret = pthread_mutex_unlock(&sched->start_work_mutex);
>
> ...;
>
> ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> ret = pthread_mutex_unlock(&sched->work_done_wait_mutex);
> ..;
>
> }
>
>
> Thanks,
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Possible deadlock errors in tools/perf/builtin-sched.c
2021-08-31 18:46 ` Jiri Olsa
@ 2021-09-01 5:19 ` CAI Yuandao
0 siblings, 0 replies; 3+ messages in thread
From: CAI Yuandao @ 2021-09-01 5:19 UTC (permalink / raw)
To: Jiri Olsa
Cc: peterz, mingo, acme, mark.rutland, alexander.shishkin, namhyung,
linux-perf-users, linux-kernel, 叶澄锋
Hi Jirka,
They were found by our static code analyzer and manually checked as true positives by us. Are they real bugs?
Best,
Ryan
On 1/9/2021, 2:46 AM, "Jiri Olsa" <jolsa@redhat.com> wrote:
On Sat, Aug 28, 2021 at 03:57:17PM +0800, 叶澄锋 wrote:
> Dear developers:
>
> Thank you for your checking.
>
> It seems there are two deadlock errors on the lock
> *sched->work_done_wait_mutex*and*sched->start_work_mutex.*
>
> They are triggered due to one thread(A) runs function *run_one_test* locating
> in a loop and unreleasing the two locks in the*wait_for_tasks*function, and
> another thread(B) runs function *thread_func *acquiring the two locks.
>
> Because the two locks are not properly released in thread A, there will be
> a deadlock problem if thread B acquires the two locks.
hi,
do you have a way to reproduce this?
thanks,
jirka
>
> The related codes are below:
>
> Thread A:
>
> static void create_tasks(struct perf_sched *sched)
> {
> ...;
> err = pthread_mutex_lock(&sched->start_work_mutex);
> ...;
> err = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> }
> static int perf_sched__replay(struct perf_sched *sched)
> {
> ...;
>
> create_tasks(sched);
> printf("------------------------------------------------------------\n");
> for (i = 0; i < sched->replay_repeat; i++)
> run_one_test(sched); // multiple reacquisition on the lock
> sched->work_done_wait_mutex and sched->start_work_mutex
>
> return 0;
> }
>
> static void run_one_test(struct perf_sched *sched)
> {
> ...;
> wait_for_tasks(sched);
> ...;
> }
> static void wait_for_tasks(struct perf_sched *sched)
> {
> ...;
> pthread_mutex_unlock(&sched->work_done_wait_mutex);
>
> ...;
> ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> pthread_mutex_unlock(&sched->start_work_mutex);
>
> ...;
>
> ret = pthread_mutex_lock(&sched->start_work_mutex);
> ....;
> }
>
> Thread B:
>
> static void *thread_func(void *ctx)
> {
>
> ...;
> ret = pthread_mutex_lock(&sched->start_work_mutex);
> ...;
> ret = pthread_mutex_unlock(&sched->start_work_mutex);
>
> ...;
>
> ret = pthread_mutex_lock(&sched->work_done_wait_mutex);
> ...;
> ret = pthread_mutex_unlock(&sched->work_done_wait_mutex);
> ..;
>
> }
>
>
> Thanks,
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <CAAo+4rXNLdgvAiT2-B8cWtLNPnWoGo9RWMW=8SPchzRgxJ4BhA@mail.gmail.com>
2021-08-28 8:06 ` Possible deadlock errors in tools/perf/builtin-sched.c 叶澄锋
2021-08-31 18:46 ` Jiri Olsa
2021-09-01 5:19 ` CAI Yuandao
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