Re: [PATCH 2/7] genirq/affinity: assign vectors to all present CPUs

From	Christoph Hellwig <hch@lst.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/7] genirq/affinity: assign vectors to all present CPUs
Date	2017-05-23 11:40 +0200
Message-ID	<tKesh-1hY-5@gated-at.bofh.it> (permalink)
References	<tILVn-84l-11@gated-at.bofh.it> <tILVo-84l-35@gated-at.bofh.it> <tJDVL-2VV-1@gated-at.bofh.it>
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On Sun, May 21, 2017 at 08:31:47PM +0200, Thomas Gleixner wrote:
> On Fri, 19 May 2017, Christoph Hellwig wrote:
> > -	/* Stabilize the cpumasks */
> > -	get_online_cpus();
> 
> How is that protected against physical CPU hotplug? Physical CPU hotplug
> manipulates the present mask.

It does indeed seem to.  Documentation/core-api/cpu_hotplug.rst claims
there are no locking rules for manipulations of cpu_present_mask,
maybe it needs and update to mention get/put_online_cpus() ?

Or maybe I should just switch to possible_cpu mask here like a lot of
code seems to do to avoid the hot plug issues, but that might be a bit
of a waste.

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spread MSI(-X) vectors to all possible CPUs V2 Christoph Hellwig <hch@lst.de> - 2017-05-19 11:00 +0200
  [PATCH 1/7] genirq: allow assigning affinity to present but not online CPUs Christoph Hellwig <hch@lst.de> - 2017-05-19 11:00 +0200
  [PATCH 2/7] genirq/affinity: assign vectors to all present CPUs Christoph Hellwig <hch@lst.de> - 2017-05-19 11:00 +0200
    Re: [PATCH 2/7] genirq/affinity: assign vectors to all present  CPUs Thomas Gleixner <tglx@linutronix.de> - 2017-05-21 20:40 +0200
      Re: [PATCH 2/7] genirq/affinity: assign vectors to all present CPUs Christoph Hellwig <hch@lst.de> - 2017-05-23 11:40 +0200

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