linux-kernel - Re: [PATCH] workqueue: fix selection of wake_cpu in kick

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Message-ID: <ZiFCn2RLWhk7i4oB@slm.duckdns.org>
Date: Thu, 18 Apr 2024 05:56:15 -1000
From: Tejun Heo <tj@...nel.org>
To: Sven Schnelle <svens@...ux.ibm.com>
Cc: Lai Jiangshan <jiangshanlai@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] workqueue: fix selection of wake_cpu in kick_pool()

On Thu, Apr 18, 2024 at 07:54:37AM +0200, Sven Schnelle wrote:
> Tejun Heo <tj@...nel.org> writes:
> 
> > Hello,
> >
> > On Wed, Apr 17, 2024 at 05:36:38PM +0200, Sven Schnelle wrote:
> >> > This generally seems like a good idea but isn't this still racy? The CPU may
> >> > go down between setting p->wake_cpu and wake_up_process().
> >> 
> >> Don't know without reading the source, but how does this code normally
> >> protect against that?
> >
> > Probably by wrapping determining the wake_cpu and the wake_up inside
> > cpu_read_lock() section.
> 
> Thanks. Should i send a v2 and incorporate your additional changes or do
> you want to do that?

Yes, please send a v2.

Thanks.

-- 
tejun