netdev - Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership.

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Date:	Wed, 02 May 2007 15:40:20 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Kumar Gala <galak@...nel.crashing.org>
CC:	jgarzik@...ox.com, netdev@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor
 ownership.

Kumar Gala wrote:
> On May 2, 2007, at 3:12 PM, Scott Wood wrote:
>> wmb() is a sync, smp_wmb() is an eieio.  Andy told me he would not  
>> accept a sync in those spots.
> 
> 
> Sorry, was looking at the iobarrier code.
> 
>> And the driver is already ppc-specific; it uses in/out_be32.
> 
> 
> True, but its hidden behind the gfar_read/write accessors.
> 
> Your change is a bit more blatant.

Well, Segher doesn't want me to use iobarrier (because it's not I/O). 
Andy doesn't want me to use wmb() (because it's sync).  I don't think 
something like gfar_wmb() would be appropriate.  So the remaining 
options are either eieio(), or a new non-arch-specific, 
non-driver-specific mem_wmb() (or whatever).

While I like the latter option, I don't think this bugfix should have to 
wait for it.

-Scott
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