From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752441Ab2KTSCF (ORCPT ); Tue, 20 Nov 2012 13:02:05 -0500 Received: from shards.monkeyblade.net ([149.20.54.216]:42104 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751807Ab2KTSCE (ORCPT ); Tue, 20 Nov 2012 13:02:04 -0500 Date: Tue, 20 Nov 2012 13:02:02 -0500 (EST) Message-Id: <20121120.130202.1918742054229219388.davem@davemloft.net> To: shemminger@vyatta.com Cc: paolo.valente@unimore.it, jhs@mojatatu.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, rizzo@iet.unipi.it, fchecconi@gmail.com Subject: Re: [PATCH] pkt_sched: QFQ Plus: fair-queueing service at DRR cost From: David Miller In-Reply-To: <20121120095304.420ded7c@nehalam.linuxnetplumber.net> References: <20121119.184828.628106002307042971.davem@davemloft.net> <50ABC19E.9030209@unimore.it> <20121120095304.420ded7c@nehalam.linuxnetplumber.net> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stephen Hemminger Date: Tue, 20 Nov 2012 09:53:04 -0800 > There are actually lots of bogus warnings than seem to only occur > because gcc 4.4 does a bad job of checking. Later versions are fixed > and don't generate warnings. > > My preference is to not add the unnecessary initialization because > if you get in the habit of doing it. The whole purpose of the uninitialized > check is lost. Try again, this was with gcc-4.7.2-2 on Fedora. There are too many preconditions, across multiple basic block, which together ensure the skb is in fact initialized at the point in question and the compiler simply isn't sophisticated enough to see that.