From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] usbnet: do not pretend to support SG/TSO
Date: Fri, 26 Jul 2013 13:48:41 -0700 (PDT)
Message-ID: <20130726.134841.350005683675289021.davem@davemloft.net>
References: <1374623813.3449.52.camel@edumazet-glaptop>
	<1374624310.3449.53.camel@edumazet-glaptop>
	<1374624954.3449.61.camel@edumazet-glaptop>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Cc: bhutchings@solarflare.com, oliver@neukum.org, grundler@google.com,
	freddy@asix.com.tw, netdev@vger.kernel.org,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	louis@asix.com.tw, allan@asix.com.tw
To: eric.dumazet@gmail.com
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1374624954.3449.61.camel@edumazet-glaptop>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 23 Jul 2013 17:15:54 -0700

> From: Eric Dumazet <edumazet@google.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@asix.com.tw>
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied, thanks Eric.