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Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed()

From Wanpeng Li <wanpeng.li@hotmail.com>
Newsgroups linux.kernel
Subject Re: [PATCH] sched: fix tsk->pi_lock isn't held when do_set_cpus_allowed()
Date 2015-08-25 10:40 +0200
Message-ID <q1hVV-1br-19@gated-at.bofh.it> (permalink)
References <q1hCx-P0-5@gated-at.bofh.it> <q1hCx-P0-3@gated-at.bofh.it> <q1hMe-10g-9@gated-at.bofh.it> <q1hVV-1br-21@gated-at.bofh.it>
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On 8/25/15 4:30 PM, Ingo Molnar wrote:
> * Wanpeng Li <wanpeng.li@hotmail.com> wrote:
>
>>>> --- a/kernel/cpuset.c
>>>> +++ b/kernel/cpuset.c
>>>> @@ -2376,8 +2376,12 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
>>>>   void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
>>>>   {
>>>> +	unsigned long flags;
>>>> +
>>>>   	rcu_read_lock();
>>>> +	raw_spin_lock_irqsave(&tsk->pi_lock, flags);
>>>>   	do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
>>>> +	raw_spin_lock_irqsave(&tsk->pi_lock, flags);
>>> Just curious, Will introduce deadlock after acquire lock twice? ;)
>> Could you point out where acquires lock twice?
> In the code you quote?

Shame me, sorry for sending out the wrong version. I fix in it soon in v2.

Regards,
Wanpeng Li

>
> Thanks,
>
> 	Ingo

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Re: [PATCH] sched: fix tsk->pi_lock isn't held when  do_set_cpus_allowed() Leo Yan <leo.yan@linaro.org> - 2015-08-25 10:20 +0200
  Re: [PATCH] sched: fix tsk->pi_lock isn't held when  do_set_cpus_allowed() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-08-25 10:30 +0200
    Re: [PATCH] sched: fix tsk->pi_lock isn't held when  do_set_cpus_allowed() Wanpeng Li <wanpeng.li@hotmail.com> - 2015-08-25 10:40 +0200
    Re: [PATCH] sched: fix tsk->pi_lock isn't held when  do_set_cpus_allowed() Ingo Molnar <mingo@kernel.org> - 2015-08-25 10:40 +0200

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