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From: Alexander Duyck <alexander.h.duyck@redhat.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>
Cc: romieu@fr.zoreil.com, netdev@vger.kernel.org, nix@esperi.org.uk,
	rl@hellgate.ch, gurligebis@gentoo.org
Subject: Re: [PATCH net-next 1/4] via-rhine: commit receive buffer address before descriptor status update.
Date: Tue, 07 Apr 2015 15:12:28 -0700	[thread overview]
Message-ID: <5524564C.9090809@redhat.com> (raw)
In-Reply-To: <1428443685.25985.212.camel@edumazet-glaptop2.roam.corp.google.com>


On 04/07/2015 02:54 PM, Eric Dumazet wrote:
> On Tue, 2015-04-07 at 17:27 -0400, David Miller wrote:
>
>> That's exactly dma_wmb().
>>
>> It barriers cpu writes so that the device sees things in a certain
>> order.
>>
>> It's what all the most common ethernet chip drivers use in their
>> descriptor handling routines now.
> To be fair, only 2 drivers currently use dma_wmb()

Hey, I got at least 4..  :-)  I only got around to patching 3 Intel 
drivers and one RealTek since that is what I had to test with.  I was 
honestly hoping there would be more interest from other developers to 
pick this up and update their drivers to avoid unnecessary barriers but 
it doesn't look like I have had much luck on that front.

Maybe what I can do is submit a set of patches over the next couple of 
weeks to try and update all the spots that either need to have a barrier 
added, such as what is being addressed here, or can have a barrier 
weakened as I have already done for a few other drivers.

- Alex

  reply	other threads:[~2015-04-07 22:12 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-06 18:01 [PATCH RFT net-next 0/4] via-rhine receive buffers rework Francois Romieu
2015-04-06 18:01 ` [PATCH net-next 1/4] via-rhine: commit receive buffer address before descriptor status update Francois Romieu
2015-04-07 19:52   ` David Miller
2015-04-07 21:02     ` Francois Romieu
2015-04-07 21:19       ` Alexander Duyck
2015-04-07 21:27       ` David Miller
2015-04-07 21:54         ` Eric Dumazet
2015-04-07 22:12           ` Alexander Duyck [this message]
2015-04-07 22:22             ` Eric Dumazet
2015-04-07 23:20               ` Alexander Duyck
2015-04-08 11:40                 ` David Laight
2015-04-07 19:54   ` Alexander Duyck
2015-04-06 18:01 ` [PATCH net-next 2/4] via-rhine: add allocation helpers Francois Romieu
2015-04-06 18:01 ` [PATCH net-next 3/4] via-rhine: gotoize rhine_open error path Francois Romieu
2015-04-06 18:01 ` [PATCH net-next 4/4] via-rhine: forbid holes in the receive descriptor ring Francois Romieu
2015-04-06 21:46 ` [PATCH RFT net-next 0/4] via-rhine receive buffers rework Nix
2015-04-07 10:46   ` Nix
2015-04-07 19:31     ` Francois Romieu
2015-04-07 19:41       ` Nix

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