linux-kernel - Re: [PATCH 1/2] percpu: allow pcpu_alloc() to be called with IRQs off

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Date:	Tue, 27 Oct 2009 13:55:27 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Jiri Kosina <jkosina@...e.cz>
CC:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Jeff Mahoney <jeffm@...e.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>, linux-ia64@...r.kernel.org
Subject: Re: [PATCH 1/2] percpu: allow pcpu_alloc() to be called with IRQs
 off

Jiri Kosina wrote:
> pcpu_alloc() and pcpu_extend_area_map() perform a series of
> spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe
> with respect to being called from contexts which have IRQs off.
> 
> This patch converts the code to perform save/restore of flags instead,
> making pcpu_alloc() (or __alloc_percpu() respectively) to be called
> from early kernel startup stage, where IRQs are off.
> 
> This is needed for proper initialization of per-cpu rq_weight data from
> sched_init().
> 
> Signed-off-by: Jiri Kosina <jkosina@...e.cz>

Acked-by: Tejun Heo <tj@...nel.org>

I'll wait for response on the series and push it through percpu#fixes
tomorrow if there's no objection.

Thanks.

-- 
tejun
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