From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757624AbbBFQYl (ORCPT ); Fri, 6 Feb 2015 11:24:41 -0500 Received: from smtprelay0183.hostedemail.com ([216.40.44.183]:33271 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753938AbbBFQYk (ORCPT ); Fri, 6 Feb 2015 11:24:40 -0500 X-Session-Marker: 6E657665747340676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::,RULES_HIT:41:355:379:541:599:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3353:3622:3865:3868:3870:3871:3872:5007:6261:7576:7808:7875:10004:10400:10848:10967:11026:11232:11658:11914:12043:12114:12296:12517:12519:12555:12740:13069:13161:13229:13255:13311:13357:21080:21088,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: maid93_7eb8484bd3644 X-Filterd-Recvd-Size: 2560 Date: Fri, 6 Feb 2015 11:24:29 -0500 From: Steven Rostedt To: Al Viro Cc: linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH v2 3/7] trace_events_filter.c: switch to memcmp() and memmem() for matching Message-ID: <20150206112429.6772a254@gandalf.local.home> In-Reply-To: <1423195215-25134-3-git-send-email-viro@ZenIV.linux.org.uk> References: <20150205224632.GW29656@ZenIV.linux.org.uk> <1423195215-25134-3-git-send-email-viro@ZenIV.linux.org.uk> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) 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 On Fri, 6 Feb 2015 04:00:11 +0000 Al Viro wrote: > From: Al Viro > > we know the lengths in advance... > > Signed-off-by: Al Viro > --- > kernel/trace/trace_events_filter.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c > index ced69da..6c4a96b 100644 > --- a/kernel/trace/trace_events_filter.c > +++ b/kernel/trace/trace_events_filter.c > @@ -271,21 +271,25 @@ static int filter_pred_none(struct filter_pred *pred, void *event) > > static int regex_match_full(char *str, struct regex *r, int len) > { > - if (strncmp(str, r->pattern, len) == 0) > + if (len - 1 != r->len) > + return 0; > + if (memcmp(str, r->pattern, r->len) == 0) > return 1; > return 0; > } > > static int regex_match_front(char *str, struct regex *r, int len) > { > - if (strncmp(str, r->pattern, r->len) == 0) > + if (len - 1 < r->len) > + return 0; > + if (memcmp(str, r->pattern, r->len) == 0) > return 1; > return 0; > } > > static int regex_match_middle(char *str, struct regex *r, int len) > { > - if (strnstr(str, r->pattern, len)) > + if (memmem(str, len, r->pattern, r->len)) Since len includes '\0', shouldn't this be: if (memmem(str, len - 1, r->pattern, r->len); It doesn't break the code either way, the algorithm still works, and the original code did not pass in len-1 either. But if this is optimizing the code, might as well eliminate one extra loop. -- Steve > return 1; > return 0; > }