From: Suresh Siddha <suresh.b.siddha@intel.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"mm-commits@vger.kernel.org" <mm-commits@vger.kernel.org>,
"jens.axboe@oracle.com" <jens.axboe@oracle.com>,
"mingo@elte.hu" <mingo@elte.hu>,
"nickpiggin@yahoo.com.au" <nickpiggin@yahoo.com.au>,
"rusty@rustcorp.com.au" <rusty@rustcorp.com.au>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: + generic-ipi-fix-the-race-between-generic_smp_call_function_-and-hotplug_cfd.patch added to -mm tree
Date: Mon, 21 Sep 2009 22:32:33 -0700 [thread overview]
Message-ID: <1253597553.2519.8.camel@sbs-t61> (raw)
In-Reply-To: <4AB6FB62.3000605@cn.fujitsu.com>
On Sun, 2009-09-20 at 21:04 -0700, Xiao Guangrong wrote:
>
> Suresh Siddha wrote:
> >
> > I am referring to the missing csd_lock_wait() here that you had in the
> > first version of your patch. Let's say, if cpu X is going offline, we
> > need to ensure that the smp_call_function() initiated by cpu X (i.e.,
> > smp_call_function IPI sent to some other cpu's from cpu X) got serviced
> > before cpu X goes offline. We can't do csd_lock_wait() here, as that
> > might deadlock (as all the other cpu's are already in stop machine with
> > interrupts disabled).
> >
>
> It not happen because the preemption is disabled while send IPI request and
> can't schedule to stop machine path, it also stop cpu down.
Xiao, I am getting confused. I am referring to case '1' mentioned by you
here http://marc.info/?l=linux-kernel&m=125265516529139&w=2
thanks,
suresh
next prev parent reply other threads:[~2009-09-22 5:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200907310030.n6V0Uqgw001644@imap1.linux-foundation.org>
[not found] ` <1252616988.7205.102.camel@laptop>
2009-09-11 7:45 ` + generic-ipi-fix-the-race-between-generic_smp_call_function_-and-hotplug_cfd.patch added to -mm tree Xiao Guangrong
2009-09-11 7:50 ` Peter Zijlstra
2009-09-11 19:08 ` Suresh Siddha
2009-09-14 7:22 ` Xiao Guangrong
2009-09-15 0:16 ` Suresh Siddha
2009-09-15 2:03 ` Xiao Guangrong
2009-09-16 2:20 ` Suresh Siddha
2009-09-17 3:00 ` Xiao Guangrong
2009-09-17 7:45 ` Peter Zijlstra
2009-09-19 2:16 ` Suresh Siddha
2009-09-21 2:55 ` Xiao Guangrong
2009-09-21 3:11 ` Suresh Siddha
2009-09-21 4:04 ` Xiao Guangrong
2009-09-22 5:32 ` Suresh Siddha [this message]
2009-09-22 6:52 ` Xiao Guangrong
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