linux-kernel - Re: [patch]workqueue: copy attr with all fields.

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Message-ID: <20130730054955.GA5225@kernel.org>
Date:	Tue, 30 Jul 2013 13:49:55 +0800
From:	Shaohua Li <shli@...nel.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [patch]workqueue: copy attr with all fields.

On Mon, Jul 29, 2013 at 11:35:23AM -0400, Tejun Heo wrote:
> Hello,
> 
> On Mon, Jul 29, 2013 at 08:52:59PM +0800, Shaohua Li wrote:
> > Ah, ok, I thought it's straightforward... It's a bug fix.
> 
> It never is, seriously.  If it's something trivial / straighforward,
> please say so in the patch description because not doing so forces
> other people to guess the intention behind the change which sucks and
> this isn't even that trivial.
> 
> > echo '0' > /sys/bus/workqueue/devices/xxx/numa
> > cat /sys/bus/workqueue/devices/xxx/numa
> > I got 1. It should be 0, the reason is copy_workqueue_attrs() called in
> > apply_workqueue_attrs() doesn't copy no_numa field.
> 
> Note that copy_workqueue_attrs() is also used while creating worker
> pools and this change would mean that there will be worker pools with
> no_numa attribute assigned basically randomly depending on which wq
> created the pool for the first time which should be fine AFAICS but
> isn't very nice.  Given that there's only single place where a pool's
> attrs is set, maybe it'd be best to clear no_numa right after copy and
> explain what's going on there?

alloc_workqueue_attrs() always zero the new allocated attr.

Thanks,
Shaohua
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