From: Greg KH Date: Mon, 03 Jul 2017 06:19:37 +0000 Subject: Re: [PATCH] staging: sm750fb: skip unnecessary comparisons Message-Id: <20170703061937.GA13523@kroah.com> List-Id: References: <20170703001809.GA1480@lynnl.wit> In-Reply-To: <20170703001809.GA1480@lynnl.wit> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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