From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: [PATCH v2.57] datapath: Add basic MPLS support to kernel Date: Tue, 20 May 2014 13:18:37 +0100 Message-ID: <20140520121837.GC23328@casper.infradead.org> References: <1400195227-21265-1-git-send-email-horms@verge.net.au> <1400195227-21265-2-git-send-email-horms@verge.net.au> <20140516084809.GA18920@verge.net.au> <20140516214806.GH8346@casper.infradead.org> <20140517013224.GA25978@verge.net.au> <20140519220219.GA20590@verge.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "dev-yBygre7rU0TnMu66kgdUjQ@public.gmane.org" , Ravi K , netdev To: Simon Horman Return-path: Content-Disposition: inline In-Reply-To: <20140519220219.GA20590-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-yBygre7rU0TnMu66kgdUjQ@public.gmane.org Sender: "dev" List-Id: netdev.vger.kernel.org On 05/20/14 at 07:02am, Simon Horman wrote: > [PATCH] datapath: 16bit inner_network_header field in struct ovs_gso_cb > > The motivation for this is to create a 16bit hole in struct ovs_gso_cb > which may be used for the inner_protocol field which is needed > for the proposed implementation of compatibility for MPLS GSO segmentation. > > This should be safe as inner_network_header is now an offset to > the inner_mac_header rather than skb->head. > > As pointed out by Thomas Graf simply making both inner offsets 16bis is not > safe as there have been cases of overflow with "with collapsed TCP frames > on IB when the headroom grew beyond 64K. See commit 50bceae9bd ``tcp: > Reallocate headroom if it would overflow csum_start'' for additional > details." > > This patch is based on suggestions by Thomas Graf and Jesse Gross. > > Cc: Thomas Graf > Cc: Jesse Gross > Signed-off-by: Simon Horman LGTM Reviewed-by: Thomas Graf