linux-kernel - Re: [PATCH] incorrect use of init

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Date:	Wed, 24 Dec 2014 20:11:07 +0100
From:	Nicholas Mc Guire <der.herr@...r.at>
To:	Prarit Bhargava <prarit@...hat.com>
Cc:	Dan Williams <dan.j.williams@...el.com>,
	Vinod Koul <vinod.koul@...el.com>, dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] incorrect use of init_completion fixup

On Wed, 24 Dec 2014, Prarit Bhargava wrote:

> 
> 
> On 12/23/2014 12:52 PM, Nicholas Mc Guire wrote:
> > The successive init_completion calls should be reinit_completion here.
> > 
> 
> Hi Nicholas,
> 
> I know enough about this code to break it ;) ... what condition did you hit that
> led you to this patch?
>

Was writing up documentation for completion (also posted today) and the 
intended API is reinit_completion which is just resetting the counter but
not touching the related waitqueu. So the failure scenario would be
a race between accessing elements on the current wait-queue and the 
init_completion reinitializing this very wait-queue. 

Further if switching from init_completion -> reinit_completion brakes
anything then it really *is* broken now.

thx!
hofrat
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