Re: [PATCH 1/2] signal: simplify deadlock-avoidance in lock_task_sighand()
From: Rik van Riel
Date: Tue Sep 23 2014 - 07:46:30 EST
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On 09/22/2014 05:24 PM, Steven Rostedt wrote:
> On Mon, 22 Sep 2014 21:11:30 +0200 Oleg Nesterov <oleg@xxxxxxxxxx>
> wrote:
>> so this patch doesn't try to change the rules.
>>
>> But perhaps we can simply remove this preempt_disable/enable?
>>
>> Or. We can shift rcu_read_unlock() from lock_task_sighand() to
>> unlock_task_sighand(). This way we can avoid preempt_disable too,
>> but I'd prefer to not do this.
>
> I really thing the preempt_disable/enable is not needed.
>
> Paul, Thomas, care to comment?
I suspect you are right. On normal kernels, rcu_read_lock() will
ensure preemption is disabled.
On -rt, the locks within are all sleepable mutexes.
Either way, things should be ok.
- --
All rights reversed
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