linux-kernel - Re: [PATCH] sched/vtime: Prevent unstable evaluation of WARN(vtime->state)

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Date:   Fri, 14 Feb 2020 17:23:09 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: [PATCH] sched/vtime: Prevent unstable evaluation of
 WARN(vtime->state)

On Thu, Jan 23, 2020 at 07:08:49PM +0100, Frederic Weisbecker wrote:
> From: Chris Wilson <chris@...is-wilson.co.uk>
> 
> As the vtime is sampled under loose seqcount protection by kcpustat, the
> vtime fields may change as the code flows. Where logic dictates a field
> has a static value, use a READ_ONCE.
> 
> Fixes: 74722bb223d0 ("sched/vtime: Bring up complete kcpustat accessor")
> Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...nel.org>
> Signed-off-by: Frederic Weisbecker <frederic@...nel.org>

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