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Date: Thu, 13 Apr 2017 10:50:54 -0400 (EDT)
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Subject: Re: [patch V2 12/13] cpufreq/sparc-us2e: Replace racy task
 affinity logic
From: David Miller <davem@davemloft.net>
In-Reply-To: <alpine.DEB.2.20.1704131017590.2408@nanos>
References: <20170412200726.941336635@linutronix.de>
        <20170412201043.129216383@linutronix.de>
        <alpine.DEB.2.20.1704131017590.2408@nanos>
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From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 13 Apr 2017 10:19:07 +0200 (CEST)

> spu_queue_register() needs to invoke setup functions on a particular
> CPU. This is achieved by temporarily setting the affinity of the
> calling user space thread to the requested CPU and reset it to the original
> affinity afterwards.
> 
> That's racy vs. CPU hotplug and concurrent affinity settings for that
> thread resulting in code executing on the wrong CPU and overwriting the
> new affinity setting.
> 
> Replace it by using work_on_cpu_safe() which guarantees to run the code on
> the requested CPU or to fail in case the CPU is offline.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

Acked-by: David S. Miller <davem@davemloft.net>