Re: [PATCH 1/2] signal: simplify deadlock-avoidance in lock_task_sighand()

From: Peter Zijlstra
Date: Tue Sep 23 2014 - 10:20:45 EST


On Tue, Sep 23, 2014 at 07:45:22AM -0400, Rik van Riel wrote:

> > 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.

But with CONFIG_PREEMPT we get preemptible RCU but not the
spinlock->rt_mutex conversion.
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