From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752199AbdGCGTk (ORCPT ); Mon, 3 Jul 2017 02:19:40 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58840 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbdGCGTi (ORCPT ); Mon, 3 Jul 2017 02:19:38 -0400 Date: Mon, 3 Jul 2017 08:19:37 +0200 From: Greg KH To: Lynn Lei Cc: sudipm.mukherjee@gmail.com, devel@driverdev.osuosl.org, linux-fbdev@vger.kernel.org, teddy.wang@siliconmotion.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] staging: sm750fb: skip unnecessary comparisons Message-ID: <20170703061937.GA13523@kroah.com> References: <20170703001809.GA1480@lynnl.wit> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170703001809.GA1480@lynnl.wit> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 03, 2017 at 09:26:47AM +0800, Lynn Lei wrote: > introduced early checks to skip unnecessary comparisons when flags set. Why? > > Signed-off-by: Lynn Lei > --- > drivers/staging/sm750fb/sm750.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/staging/sm750fb/sm750.c b/drivers/staging/sm750fb/sm750.c > index 386d4adcd91d..9e57a2d32465 100644 > --- a/drivers/staging/sm750fb/sm750.c > +++ b/drivers/staging/sm750fb/sm750.c > @@ -1171,11 +1171,16 @@ static int __init lynxfb_setup(char *options) > */ > while ((opt = strsep(&options, ":")) != NULL) { > /* options that mean for any lynx chips are configured here */ > - if (!strncmp(opt, "noaccel", strlen("noaccel"))) { > + > + /* > + * NOTE: the length of options is hard-coded > + * if any of those options changed please update its length > + */ That's not good, why require this? What is wrong with the original code here? It doesn't have that type of restriction, right? > + if (!g_noaccel && !strncmp(opt, "noaccel", 7)) { > g_noaccel = 1; > - } else if (!strncmp(opt, "nomtrr", strlen("nomtrr"))) { > + } else if (!g_nomtrr && !strncmp(opt, "nomtrr", 6)) { I don't see the benefit of this change at all, what am I missing? thanks, greg k-h