netdev - RE: [PATCH 4/4] net/mlx4_en: Use atomic counter to decide when queue is full

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Message-ID: <953B660C027164448AE903364AC447D2868104FE@MTLDAG02.mtl.com>
Date:	Mon, 25 Jun 2012 13:06:06 +0000
From:	Yevgeny Petrilin <yevgenyp@...lanox.com>
To:	David Miller <davem@...emloft.net>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH 4/4] net/mlx4_en: Use atomic counter to decide when
 queue is full

> > The Transmit and transmit completion flows execute from different
> > contexts, which are not synchronized. Hence naive reading the of
> > consumer index might give wrong value by the time it is being used, That could lead to a state of transmit timeout.
> > Fix that by using atomic variable to maintain that index.
> >
> > Signed-off-by: Yevgeny Petrilin <yevgenyp@...lanox.co.il>
> 
> I'm not convinced.  There is only one place that actually changes the counter.
> 
> So it seems more like you have a missing memory barrier somewhere.
> 
> Other drivers do not need to use something as expansive as an atomic
> variable for this and neither should you.
> 
> I'm not applying this patch series, you'll need to resubmit it in it's
> entirety once you fix this patch.

Thanks,
I'll resubmit the other 3 and continue to work on this one.

Thanks,
Yevgeny
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