From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755399Ab2KUQyq (ORCPT ); Wed, 21 Nov 2012 11:54:46 -0500 Received: from mail-da0-f46.google.com ([209.85.210.46]:33987 "EHLO mail-da0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755336Ab2KUQyo (ORCPT ); Wed, 21 Nov 2012 11:54:44 -0500 Date: Wed, 21 Nov 2012 08:54:39 -0800 From: Greg KH To: Sachin Kamat Cc: linux-kernel@vger.kernel.org, patches@linaro.org Subject: Re: [PATCH 1/1] tty: vt: Remove redundant null check before kfree. Message-ID: <20121121165439.GA4421@kroah.com> References: <1353475147-28308-1-git-send-email-sachin.kamat@linaro.org> <20121121144624.GA21766@kroah.com> <20121121151604.GA21983@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 21, 2012 at 08:59:08PM +0530, Sachin Kamat wrote: > On 21 November 2012 20:46, Greg KH wrote: > > On Wed, Nov 21, 2012 at 08:21:40PM +0530, Sachin Kamat wrote: > >> On 21 November 2012 20:16, Greg KH wrote: > >> > On Wed, Nov 21, 2012 at 10:49:07AM +0530, Sachin Kamat wrote: > >> >> kfree on a NULL pointer is a no-op. > >> >> > >> >> Signed-off-by: Sachin Kamat > >> >> --- > >> >> drivers/tty/vt/consolemap.c | 6 ++---- > >> >> 1 files changed, 2 insertions(+), 4 deletions(-) > >> >> > >> >> diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c > >> >> index 2aaa0c2..248381b 100644 > >> >> --- a/drivers/tty/vt/consolemap.c > >> >> +++ b/drivers/tty/vt/consolemap.c > >> >> @@ -410,10 +410,8 @@ static void con_release_unimap(struct uni_pagedir *p) > >> >> kfree(p->inverse_translations[i]); > >> >> p->inverse_translations[i] = NULL; > >> >> } > >> >> - if (p->inverse_trans_unicode) { > >> >> - kfree(p->inverse_trans_unicode); > >> >> - p->inverse_trans_unicode = NULL; > >> >> - } > >> >> + kfree(p->inverse_trans_unicode); > >> >> + p->inverse_trans_unicode = NULL; > >> > > >> > kfree with NULL is a no-op, but the line after that just caused a kernel > >> > crash if it was NULL, so I can't accept this type of thing. > >> > > >> > Please be more careful. > >> > >> My mistake. Apologies for the same. > >> > >> Do we need to assign the pointer to NULL after freeing? > > > > It depends if it is checked later on, is it? > > I will re-send this patch after deleting the assignment? You tell me, please determine if it really is correct or not, before sending a patch. You did test this, right? greg k-h