Re: [PATCH] net: fix race in the receive/select

[Andi Kleen]

On Wed, Jul 01, 2009 at 11:39:24AM +0800, Herbert Xu wrote:
> Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
> > 
> > At least on x86 I can't see how it happens. mb() is only a compile
> > time barrier and the compiler doesn't optimize over indirect callbacks
> > like __pollwait() anyways.
> 
> mb() does more than just a compiler barrier, it also issues mfence.

mfence is not needed for normal C code (not using non temporal
stores) in the Linux memory model on x86 and is a no-op. Only the compile
time barrier matters.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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