From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751863AbaKQIXx (ORCPT ); Mon, 17 Nov 2014 03:23:53 -0500 Received: from mail4.hitachi.co.jp ([133.145.228.5]:45721 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751791AbaKQIXu (ORCPT ); Mon, 17 Nov 2014 03:23:50 -0500 Message-ID: <5469B08E.90104@hitachi.com> Date: Mon, 17 Nov 2014 17:23:42 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: SF Markus Elfring Cc: Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S. Miller" , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Coccinelle Subject: Re: [PATCH 1/1] kprobes: Deletion of an unnecessary check before the function call "module_put" References: <5307CAA2.8060406@users.sourceforge.net> <530A086E.8010901@users.sourceforge.net> <530A72AA.3000601@users.sourceforge.net> <530B5FB6.6010207@users.sourceforge.net> <530C5E18.1020800@users.sourceforge.net> <530CD2C4.4050903@users.sourceforge.net> <530CF8FF.8080600@users.sourceforge.net> <530DD06F.4090703@users.sourceforge.net> <5317A59D.4@users.sourceforge.net> <546899CF.8020808@users.sourceforge.net> In-Reply-To: <546899CF.8020808@users.sourceforge.net> 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 (2014/11/16 21:34), SF Markus Elfring wrote: > From: Markus Elfring > Date: Sun, 16 Nov 2014 12:20:31 +0100 > > The module_put() function tests whether its argument is NULL and then > returns immediately. Thus the test around the call is not needed. > > This issue was detected by using the Coccinelle software. > > Signed-off-by: Markus Elfring > --- > kernel/kprobes.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 3995f54..f1e7d45 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1527,8 +1527,7 @@ int register_kprobe(struct kprobe *p) > out: > mutex_unlock(&kprobe_mutex); > > - if (probed_mod) > - module_put(probed_mod); > + module_put(probed_mod); This is OK, but I you request a comment line over there so that code reader can understand it is safe to pass a NULL pointer to module_put(). # and of course don't touch jump label around that :) Thank you, > > return ret; > } > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com