From: Rik van Riel <riel@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>, Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] signal: simplify deadlock-avoidance in lock_task_sighand()
Date: Tue, 23 Sep 2014 07:45:22 -0400 [thread overview]
Message-ID: <54215D52.8030201@redhat.com> (raw)
In-Reply-To: <20140922172405.71c4a110@gandalf.local.home>
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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@redhat.com>
> 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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next prev parent reply other threads:[~2014-09-23 11:46 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-22 16:44 [PATCH 0/2] signal: simplify/document lock_task_sighand() logic Oleg Nesterov
2014-09-22 16:44 ` [PATCH 1/2] signal: simplify deadlock-avoidance in lock_task_sighand() Oleg Nesterov
2014-09-22 18:58 ` Steven Rostedt
2014-09-22 19:11 ` Oleg Nesterov
2014-09-22 21:24 ` Steven Rostedt
2014-09-23 11:45 ` Rik van Riel [this message]
2014-09-23 14:20 ` Peter Zijlstra
2014-09-23 14:30 ` Steven Rostedt
2014-09-23 19:03 ` Oleg Nesterov
2014-09-24 8:36 ` Paul E. McKenney
2014-09-23 15:55 ` Peter Zijlstra
2014-09-22 16:44 ` [PATCH 2/2] signal: document the RCU protection of ->sighand Oleg Nesterov
2014-09-22 19:00 ` Steven Rostedt
2014-09-23 11:50 ` Rik van Riel
2014-09-28 21:43 ` [PATCH v2 0/2] document ->sighand protection, rcu_read_unlock() deadlocks Oleg Nesterov
2014-09-28 21:44 ` [PATCH v2 1/2] signal: document the RCU protection of ->sighand Oleg Nesterov
2014-09-28 21:44 ` [PATCH v2 2/2] rcu: more info about potential deadlocks with rcu_read_unlock() Oleg Nesterov
2014-10-23 19:56 ` [PATCH v2 0/2] document ->sighand protection, rcu_read_unlock() deadlocks Oleg Nesterov
2014-10-23 20:29 ` Paul E. McKenney
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