From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932604Ab2JZMbf (ORCPT ); Fri, 26 Oct 2012 08:31:35 -0400 Received: from mga03.intel.com ([143.182.124.21]:45723 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932541Ab2JZMbe (ORCPT ); Fri, 26 Oct 2012 08:31:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,654,1344236400"; d="scan'208";a="209657159" Date: Fri, 26 Oct 2012 20:31:38 +0800 From: Yuanhan Liu To: Richard Yang Cc: Stefani Seibold , Yuanhan Liu , linux-kernel@vger.kernel.org, Andrew Morton , Fengguang Wu , Stephen Rothwell Subject: Re: [PATCH] kfifo: remove unnecessary type check Message-ID: <20121026123138.GF2778@yliu-dev.sh.intel.com> References: <1351215971-11639-1-git-send-email-yliu.null@gmail.com> <1351229911.12511.1.camel@wall-e> <20121026061145.GA2778@yliu-dev.sh.intel.com> <20121026095244.GA815@richard.(null)> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121026095244.GA815@richard.(null)> 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 Fri, Oct 26, 2012 at 05:52:44PM +0800, Richard Yang wrote: > On Fri, Oct 26, 2012 at 02:11:45PM +0800, Yuanhan Liu wrote: > >On Fri, Oct 26, 2012 at 07:38:31AM +0200, Stefani Seibold wrote: > >> Am Freitag, den 26.10.2012, 09:46 +0800 schrieb Yuanhan Liu: > >> > From: Yuanhan Liu > >> > > >> > Firstly, this kind of type check doesn't work. It does something similay > >> > like following: > >> > void * __dummy = NULL; > >> > __buf = __dummy; > >> > > >> > __dummy is defined as void *. Thus it will not trigger warnings as > >> > expected. > >> > > >> > Second, we don't need that kind of check. Since the prototype > >> > of __kfifo_out is: > >> > unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, unsigned int len) > >> > > >> > buf is defined as void *, so we don't need do the type check. Remove it. > >> > > >> > LINK: https://lkml.org/lkml/2012/10/25/386 > >> > LINK: https://lkml.org/lkml/2012/10/25/584 > >> > > >> > Cc: Andrew Morton > >> > Cc: Wei Yang > >> > Cc: Stefani Seibold > >> > Cc: Fengguang Wu > >> > Cc: Stephen Rothwell > >> > Signed-off-by: Yuanhan Liu > >> > --- > >> > include/linux/kfifo.h | 20 -------------------- > >> > 1 file changed, 20 deletions(-) > >> > > >> > diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h > >> > index 10308c6..b8c1d03 100644 > >> > --- a/include/linux/kfifo.h > >> > +++ b/include/linux/kfifo.h > >> > @@ -390,10 +390,6 @@ __kfifo_int_must_check_helper( \ > >> > unsigned int __ret; \ > >> > const size_t __recsize = sizeof(*__tmp->rectype); \ > >> > struct __kfifo *__kfifo = &__tmp->kfifo; \ > >> > - if (0) { \ > >> > - typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \ > >> > - __dummy = (typeof(__val))NULL; \ > >> > - } \ > >> > if (__recsize) \ > >> > __ret = __kfifo_in_r(__kfifo, __val, sizeof(*__val), \ > >> > __recsize); \ > >> > @@ -432,8 +428,6 @@ __kfifo_uint_must_check_helper( \ > >> > unsigned int __ret; \ > >> > const size_t __recsize = sizeof(*__tmp->rectype); \ > >> > struct __kfifo *__kfifo = &__tmp->kfifo; \ > >> > - if (0) \ > >> > - __val = (typeof(__tmp->ptr))0; \ > >> > if (__recsize) \ > >> > __ret = __kfifo_out_r(__kfifo, __val, sizeof(*__val), \ > >> > __recsize); \ > >> > @@ -473,8 +467,6 @@ __kfifo_uint_must_check_helper( \ > >> > unsigned int __ret; \ > >> > const size_t __recsize = sizeof(*__tmp->rectype); \ > >> > struct __kfifo *__kfifo = &__tmp->kfifo; \ > >> > - if (0) \ > >> > - __val = (typeof(__tmp->ptr))NULL; \ > >> > if (__recsize) \ > >> > __ret = __kfifo_out_peek_r(__kfifo, __val, sizeof(*__val), \ > >> > __recsize); \ > >> > @@ -512,10 +504,6 @@ __kfifo_uint_must_check_helper( \ > >> > unsigned long __n = (n); \ > >> > const size_t __recsize = sizeof(*__tmp->rectype); \ > >> > struct __kfifo *__kfifo = &__tmp->kfifo; \ > >> > - if (0) { \ > >> > - typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \ > >> > - __dummy = (typeof(__buf))NULL; \ > >> > - } \ > >> > (__recsize) ?\ > >> > __kfifo_in_r(__kfifo, __buf, __n, __recsize) : \ > >> > __kfifo_in(__kfifo, __buf, __n); \ > >> > @@ -565,10 +553,6 @@ __kfifo_uint_must_check_helper( \ > >> > unsigned long __n = (n); \ > >> > const size_t __recsize = sizeof(*__tmp->rectype); \ > >> > struct __kfifo *__kfifo = &__tmp->kfifo; \ > >> > - if (0) { \ > >> > - typeof(__tmp->ptr) __dummy = NULL; \ > >> > - __buf = __dummy; \ > >> > - } \ > >> > (__recsize) ?\ > >> > __kfifo_out_r(__kfifo, __buf, __n, __recsize) : \ > >> > __kfifo_out(__kfifo, __buf, __n); \ > >> > @@ -777,10 +761,6 @@ __kfifo_uint_must_check_helper( \ > >> > unsigned long __n = (n); \ > >> > const size_t __recsize = sizeof(*__tmp->rectype); \ > >> > struct __kfifo *__kfifo = &__tmp->kfifo; \ > >> > - if (0) { \ > >> > - typeof(__tmp->ptr) __dummy __attribute__ ((unused)) = NULL; \ > >> > - __buf = __dummy; \ > >> > - } \ > >> > (__recsize) ? \ > >> > __kfifo_out_peek_r(__kfifo, __buf, __n, __recsize) : \ > >> > __kfifo_out_peek(__kfifo, __buf, __n); \ > >> > >> Did you tried to compile the whole kernel including all the drivers with > >> your patch? > > > >Hi Stefani, > > > >I did a build test, it did't introduce any new compile errors and > >warnings. While, I haven't tried make allmodconfig then. Does this patch > >seems wrong to you? > > Hmm, in my mind, those warnings are produced by the code you removed. > So it is reasonable that you see no new warnings. Hi Yang, Nope. It's not hard to tell they are old warnings. And as you can see from the email I posted, I did a build compile with and without applying this patch, and does make C=2 2>/tmp/out.{before,after}. I then compared the two file, they are exactly same. So, no new warnings introduced. Thanks, Yuanhan Liu