From: Ben Hutchings <bhutchings@solarflare.com>
To: Ed Cashin <ecashin@coraid.com>
Cc: <davem@davemloft.net>, <akpm@linux-foundation.org>,
<jesse@nicira.com>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: do not disable sg for AoE
Date: Wed, 19 Sep 2012 20:55:04 +0100 [thread overview]
Message-ID: <1348084504.2636.41.camel@bwh-desktop.uk.solarflarecom.com> (raw)
In-Reply-To: <1348079358.4585@cat.he.net>
On Tue, 2012-09-18 at 20:20 -0400, Ed Cashin wrote:
> A change in a series of VLAN-related changes appears to have
> inadvertently disabled the use of the scatter gather feature of
> network cards for transmission of non-IP ethernet protocols like ATA
> over Ethernet (AoE). Below is a reference to the commit that
> introduces a "harmonize_features" function that turns off scatter
> gather when the NIC does not support hardware checksumming for the
> ethernet protocol of an sk buff.
>
> commit f01a5236bd4b140198fbcc550f085e8361fd73fa
> Author: Jesse Gross <jesse@nicira.com>
> Date: Sun Jan 9 06:23:31 2011 +0000
>
> net offloading: Generalize netif_get_vlan_features().
>
> The can_checksum_protocol function is not equipped to consider a
> protocol that does not require checksumming. Calling it for a
> protocol that requires no checksum is inappropriate.
Right, but...
[...]
> diff --git a/net/core/dev.c b/net/core/dev.c
> index d7fe32c..5531159 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2134,7 +2134,8 @@ static bool can_checksum_protocol(netdev_features_t features, __be16 protocol)
> static netdev_features_t harmonize_features(struct sk_buff *skb,
> __be16 protocol, netdev_features_t features)
> {
> - if (!can_checksum_protocol(features, protocol)) {
> + if (protocol != htons(ETH_P_AOE) &&
the generic way to check that would be skb->ip_summed != CHECKSUM_NONE.
Ben.
> + !can_checksum_protocol(features, protocol)) {
> features &= ~NETIF_F_ALL_CSUM;
> features &= ~NETIF_F_SG;
> } else if (illegal_highdma(skb->dev, skb)) {
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
next prev parent reply other threads:[~2012-09-19 19:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-19 0:20 [PATCH] net: do not disable sg for AoE Ed Cashin
2012-09-19 19:55 ` Ben Hutchings [this message]
2012-09-20 1:16 ` [PATCH 0/2] do not disable sg when packet requires no checksum Ed Cashin
2012-09-20 1:17 ` [PATCH 1/2] aoe: mark AoE packets as requiring no checksumming Ed Cashin
2012-09-20 1:25 ` Ben Hutchings
2012-09-20 1:40 ` Ed Cashin
2012-09-20 1:20 ` [PATCH 2/2] net: do not disable sg for packets requiring no checksum Ed Cashin
2012-09-19 20:00 ` [PATCH] net: do not disable sg for AoE David Miller
2012-09-19 20:14 ` Ed Cashin
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