Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755549Ab3ENAln (ORCPT ); Mon, 13 May 2013 20:41:43 -0400 Received: from mail-ee0-f48.google.com ([74.125.83.48]:49676 "EHLO mail-ee0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754656Ab3ENAlm (ORCPT ); Mon, 13 May 2013 20:41:42 -0400 From: Ruslan Bilovol To: apw@canonical.com, joe@perches.com Cc: linux-kernel@vger.kernel.org Subject: [PATCH] checkpatch: add check for wrong "if (IS_ERR_OR_NULL()) return PTR_ERR()" uses Date: Tue, 14 May 2013 03:41:37 +0300 Message-Id: <1368492098-3140-1-git-send-email-ruslan.bilovol@ti.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2425 Lines: 72 This was many times discussed by Russell King and I also was about wrong usage of IS_ERR_OR_NULL() in my patch. So I added this check and other people will be at least warned about potentially wrong usage of mentioned macro. Quoting Russell: | Well, the whole reasoning here is that IS_ERR_OR_NULL() is far too easy | to get wrong - there are too many of this kind of crap in the kernel: | | foo = some_func(); | if (IS_ERR_OR_NULL(foo)) | return PTR_ERR(foo); | | which is wrong, because if foo _is_ NULL, the function doesn't return an | error, it returns success instead. Of course, if some_func() never ever | returns NULL in the first place, that can't happen, but then the additional | test there for a NULL pointer is, to put it bluntly, total bollocks. The full discussion may be found here: http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874 Tested on: + if (IS_ERR_OR_NULL(soc_dev)) + return PTR_ERR(soc_dev); + + if (IS_ERR_OR_NULL(soc_dev)) + return soc_dev ? PTR_ERR(soc_dev) : -ENODEV; The result is: WARNING: Use of IS_ERR_OR_NULL is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874 + if (IS_ERR_OR_NULL(soc_dev)) + return PTR_ERR(soc_dev); Signed-off-by: Ruslan Bilovol --- I'm not very experienced in the perl, so feel free to comment this patch or fix it :) scripts/checkpatch.pl | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index b954de5..6ec71bd 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -3262,6 +3262,15 @@ sub process { } } +# check for wrong "if (IS_ERR_OR_NULL()) return PTR_ERR()" uses + if ($prevline =~ /\bif\s*$\s*IS_ERR_OR_NULL\s*\(\s*($Lval)\s*$\s*\)/) { + my $expr = '\s*$\s*' . quotemeta($1) . '\s*$\s*;'; + if ($line =~ /\b(\s*PTR_ERR)$expr/) { + WARN('IS_ERR_OR_NULL', + "Use of IS_ERR_OR_NULL is usually wrong: see http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874\n" . $hereprev); + } + } + # prefer usleep_range over udelay if ($line =~ /\budelay\s*$\s*(\d+)\s*$/) { # ignore udelay's < 10, however -- 1.7.9.5 -- 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/