From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752245AbaFJQzq (ORCPT ); Tue, 10 Jun 2014 12:55:46 -0400 Received: from smtprelay0038.hostedemail.com ([216.40.44.38]:42858 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752041AbaFJQzp (ORCPT ); Tue, 10 Jun 2014 12:55:45 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::,RULES_HIT:41:355:379:541:800:960:973:982:988:989:1260:1261:1277:1311:1313:1314:1345:1373:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:1981:2194:2197:2199:2200:2393:2559:2562:2828:3138:3139:3140:3141:3142:3354:3653:3865:3866:3868:3870:3871:3874:4250:4321:4470:5007:6119:6120:7652:7903:8603:8957:9040:10004:10400:10848:11026:11658:11914:12043:12517:12519:12555:13095:13146:13161:13181:13229:13230,0,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: soup76_31e5810fd3934 X-Filterd-Recvd-Size: 3197 Message-ID: <1402419340.30479.18.camel@joe-AO725> Subject: [RFC PATCH] checkpatch: Attempt to find unnecessary 'out of memory' messages From: Joe Perches To: Andrew Morton Cc: Dan Carpenter , Andy Whitcroft , LKML , Julia Lawall Date: Tue, 10 Jun 2014 09:55:40 -0700 Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.10.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Logging messages that show some type of "out of memory" error are generally unnecessary as there is a generic message and a stack dump done by the memory subsystem. These messages generally increase kernel size without much added value. Emit a warning on these types of messages. This test looks for any inserted message function, then looks at the previous line for an "if (!foo)" or "if (foo == NULL)" test and then looks at the preceding statement for an allocation function like "foo = kmalloc()" ie: this code matches: foo = kmalloc(); if (foo == NULL) { printk("Out of memory\n"); return -ENOMEM; } This test is very crude and incomplete. This test can miss quite a lot of of OOM messages that do not have this specific form. ie: this code does not match: foo = kmalloc(); if (!foo) { rtn = -ENOMEM; printk("Out of memory!\n"); goto out; } This test could also be a false positive when the logging message itself does not specify anything about memory, but I did not find any false positives in my limited testing. spatch could be a better solution but correctness seems non-trivial for that tool too. Signed-off-by: Joe Perches --- scripts/checkpatch.pl | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 010b18e..64bee42 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -4009,6 +4009,23 @@ sub process { } } +# check for unnecessary "Out of Memory" messages + if ($line =~ /^\+.*\b$logFunctions\s*\(/ && + $prevline =~ /^[ \+]\s*if\s*\(\s*(\!\s*|NULL\s*==\s*)?($Lval)(\s*==\s*NULL\s*)?\s*\)/ && + (defined $1 || defined $3) && + $linenr > 3) { + my $testval = $2; + my $testline = $lines[$linenr - 3]; + + my ($s, $c) = ctx_statement_block($linenr - 3, $realcnt, 0); +# print("line: <$line>\nprevline: <$prevline>\ns: <$s>\nc: <$c>\n\n\n"); + + if ($c =~ /(?:^|\n)[ \+]\s*(?:$Type\s*)?\Q$testval\E\s*=\s*(?:\([^\)]*\)\s*)?\s*(?:devm_)?(?:[kv][czm]alloc(?:_node|_array)?\b|kstrdup|(?:dev_)?alloc_skb)/) { + WARN("OOM_MESSAGE", + "Possible unnecessary 'out of memory' message\n" . $hereprev); + } + } + # check for bad placement of section $InitAttribute (e.g.: __initdata) if ($line =~ /(\b$InitAttribute\b)/) { my $attr = $1;