From: Andi Kleen <ak@suse.de>
To: Chuck Ebbert <cebbert@redhat.com>
Cc: Loic Prylli <loic@myri.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] MTRR: Fix race causing set_mtrr to go into infinite loop
Date: Tue, 26 Jun 2007 00:34:41 +0200 [thread overview]
Message-ID: <200706260034.41940.ak@suse.de> (raw)
In-Reply-To: <46803C1D.2040009@redhat.com>
On Tuesday 26 June 2007 00:05:17 Chuck Ebbert wrote:
> On 06/25/2007 05:38 PM, Loic Prylli wrote:
>
> [cc: Andi]
>
> > Processors synchronization in set_mtrr requires the .gate field
> > to be set after .count field is properly initialized. Without an explicit
> > barrier, the compiler was reordering those memory stores. That was sometimes
> > causing a processor (in ipi_handler) to see the .gate change and
> > decrement .count before the latter is set by set_mtrr() (which
> > then hangs in a infinite loop with irqs disabled).
Hmm, perhaps we should just put the smp_wmb into atomic_set().
Near all other atomic operations have memory barriers too. I think
that would be the better fix.
-Andi
next prev parent reply other threads:[~2007-06-25 22:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-25 21:38 [PATCH] MTRR: Fix race causing set_mtrr to go into infinite loop Loic Prylli
2007-06-25 22:05 ` Chuck Ebbert
2007-06-25 22:34 ` Andi Kleen [this message]
2007-06-26 1:40 ` Loic Prylli
2007-06-28 19:52 ` Chuck Ebbert
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