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Date: Sat, 18 Jan 2014 22:54:31 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mike Galbraith <bitbucket@online.de>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
        Len Brown <lenb@kernel.org>, linux-next@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: linux-next: build failure after merge of the tip tree
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On Sat, Jan 18, 2014 at 11:14:57AM -0800, H. Peter Anvin wrote:
> >> Could something like this work?
> >>
> >> 	local_irq_enable();
> >> 	mwait_idle_with_hints(0,0);
> >>

> This means an interrupt window is open and we can take an interrupt
> between checking need_resched and the MWAIT, which couldn't happen with
> __sti_mwait().
> 
> Are we sure that is actually safe?

current_set_polling_and_test() vs resched_task() should be good that
way, but I've got a terrible head-ache today so don't rely on anything
much I say.