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Message-Id: <20130726.134841.350005683675289021.davem@davemloft.net>
Date: Fri, 26 Jul 2013 13:48:41 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: eric.dumazet@...il.com
Cc: bhutchings@...arflare.com, oliver@...kum.org, grundler@...gle.com,
freddy@...x.com.tw, netdev@...r.kernel.org,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
louis@...x.com.tw, allan@...x.com.tw
Subject: Re: [PATCH] usbnet: do not pretend to support SG/TSO
From: Eric Dumazet <eric.dumazet@...il.com>
Date: Tue, 23 Jul 2013 17:15:54 -0700
> From: Eric Dumazet <edumazet@...gle.com>
>
> usbnet doesn't support yet SG, so drivers should not advertise SG or TSO
> capabilities, as they allow TCP stack to build large TSO packets that
> need to be linearized and might use order-5 pages.
>
> This adds an extra copy overhead and possible allocation failures.
>
> Current code ignore skb_linearize() return code so crashes are even
> possible.
>
> Best is to not pretend SG/TSO is supported, and add this again when/if
> usbnet really supports SG for devices who could get a performance gain.
>
> Based on a prior patch from Freddy Xin <freddy@...x.com.tw>
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Applied, thanks Eric.
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