From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932651AbcFCPtU (ORCPT ); Fri, 3 Jun 2016 11:49:20 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:44104 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932378AbcFCPtS (ORCPT ); Fri, 3 Jun 2016 11:49:18 -0400 Subject: Re: [PATCH] checkpatch: Flag code that returns a negative number To: Joe Perches , Nishanth Menon , Andy Whitcroft References: <1464967533-14634-1-git-send-email-nm@ti.com> <1464968493.11800.3.camel@perches.com> CC: , Andrew Morton From: "Andrew F. Davis" Message-ID: <5751A6F7.1030305@ti.com> Date: Fri, 3 Jun 2016 10:49:11 -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: <1464968493.11800.3.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 10:41 AM, Joe Perches wrote: > On Fri, 2016-06-03 at 10:25 -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 >> >> Considering typical newbie error of doing the following: >> int fn(void) >> { >> /* ... error condition ... */ >> return -1; >> } >> >> 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. > > I think it's not a newbie error to have a -1 return and it > seems like rather too many cases to even suggest be changed. > > $ git grep -E "\breturn\s+\-\s*[0-9]+" * | grep -v "^tools" | wc -l > 8388 > A quick look over some of these cases show many *should* be replaced with proper error codes. Removing the simple -1 case, which is often used for signaling one level up of an error, gives better results though: $ git grep -E "\breturn\s+\-\s*[2-9][0-9]*" * | grep -v "^tools" | wc -l 189 Andrew > >> diff --git 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 (defined($stat) && $stat =~ /^.\s*return\s*-[0-9]+\s*;/s) { >> + 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); >> + } >> + >> # unnecessary return in a void function >> # at end-of-function, with the previous line a single leading tab, then return; >> # and the line before that not a goto label target like "out:"