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
prev parent reply other threads:[~2020-12-09 11:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-10 4:31 [RT] 5.9-rt14 softirq_ctrl.lock vs listening_hash[i].lock lockdep splat 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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