Date: Fri, 9 Aug 2013 11:02:57 -0400
From: Tejun Heo <tj@kernel.org>
To: Chris Metcalf <cmetcalf@tilera.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Cody P Schafer <cody@linux.vnet.ibm.com>
Subject: Re: [PATCH v4 1/2] workqueue: add new schedule_on_cpu_mask() API
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Hello, Chris.

On Wed, Aug 07, 2013 at 04:49:44PM -0400, Chris Metcalf wrote:
> This primitive allows scheduling work to run on a particular set of
> cpus described by a "struct cpumask".  This can be useful, for example,
> if you have a per-cpu variable that requires code execution only if the
> per-cpu variable has a certain value (for example, is a non-empty list).

So, this allows scheduling work items on !online CPUs.  Workqueue does
allow scheduling per-cpu work items on offline CPUs if the CPU has
ever been online, but the behavior when scheduling work items on cpu
which has never been online is undefined.  I think the interface at
least needs to verify that the the target cpus have been online,
trigger warning and mask off invalid CPUs otherwise.

Thanks.

-- 
tejun
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