Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759608Ab2FAMiO (ORCPT ); Fri, 1 Jun 2012 08:38:14 -0400 Received: from mail-gg0-f174.google.com ([209.85.161.174]:37537 "EHLO mail-gg0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757142Ab2FAMiN convert rfc822-to-8bit (ORCPT ); Fri, 1 Jun 2012 08:38:13 -0400 MIME-Version: 1.0 In-Reply-To: <20120601104925.5135263c@kryten> References: <20120601104925.5135263c@kryten> Date: Fri, 1 Jun 2012 21:38:13 +0900 Message-ID: Subject: Re: [PATCH] fault-inject: Avoid call to random32() if fault injection is disabled From: Akinobu Mita To: Anton Blanchard Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1446 Lines: 41 2012/6/1 Anton Blanchard : > > After enabling CONFIG_FAILSLAB I noticed random32 in profiles even > if slub fault injection wasn't enabled at runtime. > > should_fail forces a comparison against random32() even if > probability is 0: > > ? ? ? ?if (attr->probability <= random32() % 100) > ? ? ? ? ? ? ? ?return false; > > Add a check up front for probability == 0 and avoid all of the more > complicated checks. > > Signed-off-by: Anton Blanchard > --- > > Index: linux-build/lib/fault-inject.c > =================================================================== > --- linux-build.orig/lib/fault-inject.c 2012-02-11 21:22:32.303459860 +1100 > +++ linux-build/lib/fault-inject.c ? ? ?2012-02-11 22:38:10.470977505 +1100 > @@ -101,6 +101,10 @@ static inline bool fail_stacktrace(struc > > ?bool should_fail(struct fault_attr *attr, ssize_t size) > ?{ > + ? ? ? /* No need to check any other properties if the probability is 0 */ > + ? ? ? if (attr->probability == 0) > + ? ? ? ? ? ? ? return false; > + > ? ? ? ?if (attr->task_filter && !fail_task(attr, current)) > ? ? ? ? ? ? ? ?return false; > Looks good to me. Acked-by: Akinobu Mita -- 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/