From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161170AbcFCUqR (ORCPT ); Fri, 3 Jun 2016 16:46:17 -0400 Received: from bear.ext.ti.com ([198.47.19.11]:34691 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161043AbcFCUqG (ORCPT ); Fri, 3 Jun 2016 16:46:06 -0400 Subject: Re: [PATCH V2] checkpatch: Flag code that returns a negative number less than 1 To: Joe Perches , Andy Whitcroft References: <1464967533-14634-1-git-send-email-nm@ti.com> <1464984122-16381-1-git-send-email-nm@ti.com> <1464986529.11800.24.camel@perches.com> CC: , , Andrew Morton From: Nishanth Menon Message-ID: <5751EC88.4020300@ti.com> Date: Fri, 3 Jun 2016 15:46:00 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1464986529.11800.24.camel@perches.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/03/2016 03:42 PM, Joe Perches wrote: > On Fri, 2016-06-03 at 15:02 -0500, Nishanth Menon wrote: >> In some functions, returning a -ve decimal value is actually a valid >> return condition when the function is returning a value, however, it >> can also be misused for returning an error value that should ideally >> be a valid error code defined in include/uapi/asm-generic/errno-base.h >> or include/uapi/asm-generic/errno.h. The notable exception is "-1" >> which has quiet a history of usage as pointed out by Joe Perches. >> >> Considering typical error of doing the following: >> int fn(void) >> { >> /* ... error condition ... */ >> return -2; >> } >> >> void fn1(void) >> { >> /* some code */ >> if (fn() < 0) { >> pr_err("Error occurred\n"); >> return; >> } >> /* other cases... */ >> } >> >> Flag this as a check case for developer verification. >> >> The check is done for negative values less than 1 and tools >> directory is exempt from this requirement based on Joe Perches' >> suggestion. >> >> Suggested-by: Joe Perches > > No, I didn't suggest this. Sorry, I had hoped to give you credit for the recommended regex optimization and recommendations you gave. > I'm not at all sure it's even a good idea. OK. I can drop this if we'd not want to go down this road. we can catch stuff in review as much as possible, I was hoping we can catch the easy ones by forcing a relook by developers. > >> Signed-off-by: Nishanth Menon >> --- >> Changes in V2: >> - change in regex for check for check for less than 1 >> - Update in commit message to the effect >> - Added Suggested-by for Joe's recommendation on regex. >> >> V1: https://patchwork.kernel.org/patch/9153345/ >> >> scripts/checkpatch.pl | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl >> index 4904ced676d4..a2e677b5fd78 100755 >> --- a/scripts/checkpatch.pl >> +++ b/scripts/checkpatch.pl >> @@ -4351,6 +4351,12 @@ sub process { >> } >> } >> >> +# return with a value is not usually a good sign, unless the function is supposed to return a value >> + if ($realfile !~ /^tools/ && defined($stat) && $stat =~ /^.\s*return\s*-\s*(?!1\b)\d+\s*;/s) { > > I think > if ($realfile != /^tools/ && $line =~ /\breturn\s*-\s*(?!1\b)\d+\s*;/ > would be better as it would catch return -2 in a macro or a > multi-line statement like > if () return -2; > Nice. >> + CHK("RETURN_NUMBER", >> + "Suspect error return with a value, If this is error value, refer to include/uapi/asm-generic/errno-base.h and include/uapi/asm-generic/errno.h\n" . $herecurr); > > That's an awfully long message. > > Maybe something like: > "Perhaps better to use standard ERRNO system error symbols" > Fair enough. Will hold off a respin based on direction we would like to take. -- Regards, Nishanth Menon