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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>,
	tglx@linutronix.de, linux-rt-users@vger.kernel.org,
	lkml <linux-kernel@vger.kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	Will Deacon <will@kernel.org>
Subject: Re: [RT] 5.9-rt14  softirq_ctrl.lock vs listening_hash[i].lock lockdep splat
Date: Wed, 9 Dec 2020 12:47:37 +0100	[thread overview]
Message-ID: <20201209114737.bvndv52pst4ownyc@linutronix.de> (raw)
In-Reply-To: <X9CheYjuXWc75Spa@hirez.programming.kicks-ass.net>

On 2020-12-09 11:05:45 [+0100], Peter Zijlstra wrote:
> In general we have the rule that as long as a lock is only ever used
> from task context (like the above ilb->lock, afaict) then it doesn't
> matter if you also take it with (soft)irqs disabled or not. But this
> softirq scheme breaks that. If you ever take a lock with BH disabled,
> you must now always take it with BH disabled, otherwise you risk
> deadlocks against the softirq_ctrl lock.
> 
> Or am I missing something obvious (again) ?

No. With this explanation it makes sense. Thank you.

Sebastian

      parent reply	other threads:[~2020-12-09 11:48 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-10  4:31 Mike Galbraith
2020-10-12 16:45 ` Sebastian Andrzej Siewior
2020-10-12 18:34   ` Mike Galbraith
2020-10-13  3:00     ` Mike Galbraith
2020-10-14 10:22       ` Sebastian Andrzej Siewior
2020-12-09 10:05 ` Peter Zijlstra
2020-12-09 10:25   ` Mike Galbraith
2020-12-09 10:32     ` Sebastian Andrzej Siewior
2020-12-09 11:47   ` Sebastian Andrzej Siewior [this message]

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