From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751878Ab1AXT4I (ORCPT ); Mon, 24 Jan 2011 14:56:08 -0500 Received: from mail.bluewatersys.com ([202.124.120.130]:6273 "EHLO hayes.bluewaternz.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751214Ab1AXT4G (ORCPT ); Mon, 24 Jan 2011 14:56:06 -0500 Message-ID: <4D3DD964.9020107@bluewatersys.com> Date: Tue, 25 Jan 2011 08:56:20 +1300 From: Ryan Mallon User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101208 Lightning/1.0b2 Thunderbird/3.1.7 MIME-Version: 1.0 To: Julia Lawall CC: Russell King , kernel-janitors@vger.kernel.org, Nicolas Ferre , Jean-Christophe PLAGNIOL-VILLARD , Andrew Victor , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] arch/arm/mach-at91/clock.c: Add missing IS_ERR test References: <1295898922-18822-1-git-send-email-julia@diku.dk> <1295898922-18822-3-git-send-email-julia@diku.dk> In-Reply-To: <1295898922-18822-3-git-send-email-julia@diku.dk> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/25/2011 08:55 AM, Julia Lawall wrote: > Function clk_get, defined just below this code, returns ERR_PTR not NULL in > an error case. > > The semantic match that finds this problem is as follows: > (http://coccinelle.lip6.fr/) > > // > @r@ > identifier f; > @@ > f(...) { ... return ERR_PTR(...); } > > @@ > identifier r.f, fld; > expression x; > statement S1,S2; > @@ > x = f(...) > ... when != IS_ERR(x) > ( > if (IS_ERR(x) ||...) S1 else S2 > | > *x->fld > ) > // I'm always really impressed by this tool :-). > > Signed-off-by: Julia Lawall > > --- > arch/arm/mach-at91/clock.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/mach-at91/clock.c b/arch/arm/mach-at91/clock.c > index 9113da6..c9ee6d0 100644 > --- a/arch/arm/mach-at91/clock.c > +++ b/arch/arm/mach-at91/clock.c > @@ -224,7 +224,7 @@ void __init at91_clock_associate(const char *id, struct device *dev, const char > { > struct clk *clk = clk_get(NULL, id); > > - if (!dev || !clk || !IS_ERR(clk_get(dev, func))) > + if (!dev || IS_ERR(clk) || !IS_ERR(clk_get(dev, func))) > return; I think we want: if (!dev || !clk || IS_ERR(clk) || !IS_ERR(clk_get(dev, func))) return; Since it is valid to return a NULL clk, and we don't want to try and dereference it if that is the case. We could also probably drop the !IS_ERR(clk_get(dev, func)) check, since as far as I can tell it is just checking to see if the clock is already associated, but there is no harm in re-assigning the same values, and the two assignments in at91_clock_associate are going to be much quicker than the lookup in clk_get. ~Ryan -- Bluewater Systems Ltd - ARM Technology Solution Centre Ryan Mallon 5 Amuri Park, 404 Barbadoes St ryan@bluewatersys.com PO Box 13 889, Christchurch 8013 http://www.bluewatersys.com New Zealand Phone: +64 3 3779127 Freecall: Australia 1800 148 751 Fax: +64 3 3779135 USA 1800 261 2934