linux-kernel - Re: [PATCH 1/2] workqueue: Add new function mod_fwd_delayed

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Message-Id: <E1cgdBA-0000LS-VU@stardust.g4.wien.funkfeuer.at>
Date:   Wed, 22 Feb 2017 21:06:23 +0100
From:   Harald Geyer <harald@...ib.org>
To:     Mark Brown <broonie@...nel.org>
cc:     Liam Girdwood <lgirdwood@...il.com>, Tejun Heo <tj@...nel.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] workqueue: Add new function mod_fwd_delayed_work()

Mark Brown writes:
> On Wed, Feb 22, 2017 at 05:41:24PM +0000, Harald Geyer wrote:
> > Drivers calling queue_delayed_work() or mod_delayed_work() multiple times
> > on the same work without coordination get undefined behaviour. Add a new
> > function, which is easier to use.
> 
> The obvious question here, especially in the case of mod_delayed_work(),
> is why not fix the existing functions to have the expected behaviour?

AFAICS the existing functions behave as documented. I don't feel to be an
authority to decide that the documented behaviour is not right. Actually
I think that what mod_delayed_work() does, is a valid operation, even
if many current users probably don't want it.

I guess many users don't care, because they are calling mod_delayed_work()
from only a single place with a constant delay. However reviewing all
107 use cases in 58 files to check if we can safely change the
behaviour, would be quite a lot of work.

I was suprised when I found that no function like mod_fwd_delayed_work()
existed, so you have a point there.

Harald
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