Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760051AbYCEGjb (ORCPT ); Wed, 5 Mar 2008 01:39:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757194AbYCEGjR (ORCPT ); Wed, 5 Mar 2008 01:39:17 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:36211 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755612AbYCEGjP (ORCPT ); Wed, 5 Mar 2008 01:39:15 -0500 Date: Wed, 5 Mar 2008 07:38:42 +0100 From: Ingo Molnar To: Julia Lawall Cc: yi.zhu@intel.com, linux-wireless@vger.kernel.org, ipw3945-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Harvey Harrison , Alexander Viro , linux-sparse@vger.kernel.org, Josh Triplett Subject: Re: [PATCH 6/9] drivers/net/wireless/iwlwifi/iwl-4965.c: Correct use of ! and & Message-ID: <20080305063842.GA24495@elte.hu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1198 Lines: 31 * Julia Lawall wrote: > From: Julia Lawall > > In commit e6bafba5b4765a5a252f1b8d31cbf6d2459da337, a bug was fixed > that involved converting !x & y to !(x & y). The code below shows the > same pattern, and thus should perhaps be fixed in the same way. > if (sta_ht_inf) { > if ((!sta_ht_inf->ht_supported) || > - (!sta_ht_inf->cap & IEEE80211_HT_CAP_SUP_WIDTH)) > + (!(sta_ht_inf->cap & IEEE80211_HT_CAP_SUP_WIDTH))) > return 0; i'm wondering, could Sparse be extended to check for such patterns? People are regularly running "make C=1" and are sending fixes to make entire subsystems sparse-warning-free, so Sparse is a nice mechanism that works and it keeps code clean in the long run. I dont think the "!X & Y" pattern is ever used legitimately [and even if it were used legitimately, it's easy to avoid the sparse false positive - while in the buggy case we have a clear bug]. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/