From: Christoph Hellwig <hch@lst.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Keith Busch <keith.busch@intel.com>,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/7] genirq/affinity: assign vectors to all present CPUs
Date: Tue, 23 May 2017 11:35:55 +0200 [thread overview]
Message-ID: <20170523093555.GA23632@lst.de> (raw)
In-Reply-To: <alpine.DEB.2.20.1705212028280.3023@nanos>
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.
next prev parent reply other threads:[~2017-05-23 9:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 8:57 spread MSI(-X) vectors to all possible CPUs V2 Christoph Hellwig
2017-05-19 8:57 ` [PATCH 1/7] genirq: allow assigning affinity to present but not online CPUs Christoph Hellwig
2017-05-19 8:57 ` [PATCH 2/7] genirq/affinity: assign vectors to all present CPUs Christoph Hellwig
2017-05-21 18:31 ` Thomas Gleixner
2017-05-23 9:35 ` Christoph Hellwig [this message]
2017-05-19 8:57 ` [PATCH 3/7] genirq/affinity: factor out a irq_affinity_set helper Christoph Hellwig
2017-05-21 19:03 ` Thomas Gleixner
2017-05-23 9:37 ` Christoph Hellwig
2017-05-19 8:57 ` [PATCH 4/7] genirq/affinity: update CPU affinity for CPU hotplug events Christoph Hellwig
2017-05-19 8:57 ` [PATCH 5/7] blk-mq: include all present CPUs in the default queue mapping Christoph Hellwig
2017-05-19 8:57 ` [PATCH 6/7] blk-mq: create hctx for each present CPU Christoph Hellwig
2017-05-19 8:57 ` [PATCH 7/7] nvme: allocate queues for all possible CPUs Christoph Hellwig
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