Messages in this thread | | | Subject | RE: [PATCH] Fix the race between smp_call_function and CPU booting | From | Peter Zijlstra <> | Date | Tue, 13 Mar 2012 16:57:31 +0100 |
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On Tue, 2012-03-13 at 06:46 +0000, Liu, Chuansheng wrote: > > > -----Original Message----- > > From: Peter Zijlstra [mailto:peterz@infradead.org] > > Sent: Monday, March 12, 2012 5:58 PM > > To: Liu, Chuansheng > > Cc: linux-kernel@vger.kernel.org; Yanmin Zhang; tglx@linutronix.de > > Subject: Re: [PATCH] Fix the race between smp_call_function and CPU booting > > > > On Mon, 2012-03-12 at 09:27 +0000, Liu, Chuansheng wrote: > > > The solution is just to send smp call to active cpus instead of online > > > cpus. > > > > BTW, that solution is broken because !active cpus can still be online and > > actually running stuff, so sending IPIs to them is perfectly fine and actually > > required. > > > Based on current code base, the IPI can be handled only after the cpu is active, before CPU is active, > Any sending IPI is meanless.
Not so on the unplug case, we clear active long before we actually go offline and rebuild sched_domains.
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