linux-kernel - Re: [PATCH] Preserve task state in reentrant calls to ___wait

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Message-ID: <20151107091954.GE17308@twins.programming.kicks-ass.net>
Date:	Sat, 7 Nov 2015 10:19:54 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Chris Bainbridge <chris.bainbridge@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	lv.zheng@...el.com, mingo@...hat.com, rjw@...ysocki.net,
	oleg@...hat.com, aystarik@...il.com
Subject: Re: [PATCH] Preserve task state in reentrant calls to ___wait_event

On Fri, Nov 06, 2015 at 08:44:08PM +0000, Chris Bainbridge wrote:
> I am assuming here that wait_event_timeout() is supposed to support reentrant
> calls.

Not really. It is sort of allowed, provided the inner one will rarely
block. And therefore the outer one will mostly work.

> If not, perhaps it should BUG_ON when called with a non-running task
> state,

There is a warning in __might_sleep() that catches some of this.

> and the SBS HC / ACPI EC code needs to be fixed to stop doing this.

Yes.
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