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Subject: Re: [PATCH] drivers/net/tile/: on-chip network drivers for the
 tile architecture
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Chris Metcalf <cmetcalf@tilera.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
In-Reply-To: <4CD19DCF.1040709@tilera.com>
References: <201011012107.oA1L7TGd031588@farm-0027.internal.tilera.com>
	 <20101103125959.3231daa1@s6510>  <4CD19DCF.1040709@tilera.com>
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Date: Wed, 03 Nov 2010 18:50:22 +0100
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Le mercredi 03 novembre 2010 à 13:37 -0400, Chris Metcalf a écrit :
> Stephen, thanks for your feedback!
> 
> On 11/3/2010 12:59 PM, Stephen Hemminger wrote:
> > 1. MUST not use volatile, see volatile-considered-harmful.txt
> 
> The "harmful" use of volatile is in trying to fake out SMP.  Believe me,
> with a 64-core architecture, we know our SMP guidelines. :-)  Our use here
> is simply to force the compiler to issue a load, for the side-effect of
> populating the TLB, for example.
> 
> However, your response does suggest that simply the syntactic use of
> "volatile" will cause a red flag for readers.  I'll move this to an inline
> function in a header with a comment explaining what it's for, and use the
> function instead.

Please read Documentation/volatile-considered-harmful.txt

Then if there is a problem, we can make change to the documentation, but
volatile use in new code is _strictly_ forbidden.

ACCESS_ONCE() is your friend, we might document it in
Documentation/volatile-considered-harmful.txt