From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757439Ab1JRKFb (ORCPT ); Tue, 18 Oct 2011 06:05:31 -0400 Received: from helcar.apana.org.au ([209.40.204.226]:43245 "EHLO fornost.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753905Ab1JRKF3 (ORCPT ); Tue, 18 Oct 2011 06:05:29 -0400 Date: Tue, 18 Oct 2011 12:05:27 +0200 From: Herbert Xu To: Eric Dumazet Cc: Elmar Vonlanthen , linux-kernel@vger.kernel.org, netdev , Timo =?iso-8859-1?Q?Ter=E4s?= Subject: Re: PROBLEM: System call 'sendmsg' of process ospfd (quagga) causes kernel oops Message-ID: <20111018100527.GA15383@gondor.apana.org.au> References: <1318604266.2223.29.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <1318905032.2571.35.camel@edumazet-laptop> <20111018093411.GA15165@gondor.apana.org.au> <1318932093.2657.26.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1318932093.2657.26.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 18, 2011 at 12:01:33PM +0200, Eric Dumazet wrote: > > Adding an RCU protected structure to hold hard_header_len / > needed_headroom / needed_tailroom should be possible, but this adds yet > another pointer dereference... I don't think we need RCU here since the problem is simply that we're using two different values for skb allocations and skb_reserve. As long as we use one and the same value it should work. The value will rarely be incorrect and when it is, automatic reallocation will occur. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt