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Date: Wed, 24 Mar 2010 08:31:26 +1100
From: Anton Blanchard <anton@samba.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>, Ingo Molnar <mingo@elte.hu>,
       Jens Axboe <jens.axboe@oracle.com>,
       Nick Piggin <nickpiggin@yahoo.com.au>,
       Rusty Russell <rusty@rustcorp.com.au>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       paulmck@linux.vnet.ibm.com, Milton Miller <miltonm@bga.com>,
       Nick Piggin <npiggin@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] smp_call_function_many SMP race
Message-ID: <20100323213126.GA5594@kryten>
References: <20100323111556.GK24064@kryten>
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Hi Peter,

> A rather simple question since my brain isn't quite ready processing the
> content here..

After working my way through that bug my brain wasn't in good shape
either because:

> Isn't reverting that one patch a simpler solution than adding all that
> extra logic? If not, then the above statement seems false and we had a
> bug even with that preempt_enable/disable() pair.

I screwed up the explanation :( The commit message that causes it is
54fdade1c3332391948ec43530c02c4794a38172 (generic-ipi: make struct
call_function_data lockless), and backing it out fixes the issue.

Anton