From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756567Ab3B0Wbg (ORCPT ); Wed, 27 Feb 2013 17:31:36 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:56815 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752474Ab3B0Wbf (ORCPT ); Wed, 27 Feb 2013 17:31:35 -0500 Date: Wed, 27 Feb 2013 14:31:33 -0800 From: Andrew Morton To: Zhang Yanfei Cc: Joe Perches , "Eric W. Biederman" , Simon Horman , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3 2/2] kexec: Use min_t to simplify logic Message-Id: <20130227143133.7208d381.akpm@linux-foundation.org> In-Reply-To: <512C789D.1090404@cn.fujitsu.com> References: <512C44E4.70907@cn.fujitsu.com> <512C4881.90409@cn.fujitsu.com> <1361867881.2023.16.camel@joe-AO722> <512C76FE.4070109@cn.fujitsu.com> <20130226005328.e2d31a97.akpm@linux-foundation.org> <512C789D.1090404@cn.fujitsu.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 26 Feb 2013 16:55:57 +0800 Zhang Yanfei wrote: > ___ 2013___02___26___ 16:53, Andrew Morton ______: > > On Tue, 26 Feb 2013 16:49:02 +0800 Zhang Yanfei wrote: > > > >>>> diff --git a/kernel/kexec.c b/kernel/kexec.c > >>> [] > >>>> @@ -822,13 +822,9 @@ static int kimage_load_normal_segment(struct kimage *image, > >>> [] > >>>> + mchunk = min_t(size_t, mbytes, > >>>> + (size_t)(PAGE_SIZE - (maddr & ~PAGE_MASK))); > >>> > >>> #define min_t(type, x, y) ({ \ > >>> type __min1 = (x); \ > >>> type __min2 = (y); \ > >>> __min1 < __min2 ? __min1: __min2; }) > >>> > >>> > >>> > >> > >> Hmm, from the definition, the cast is redundant. > >> > >> Maybe I misunderstood what Andrew meant in the mail related to v2: > >> > >> "The types of PAGE_SIZE and PAGE_MASK are vague - iirc they once had > >> different types on different architectures, so some form of casting is > >> unavoidable here." > >> > >> Andrew, could you please explain the casting you meant above? > > > > I mean that a cast (or min_t, which is a cast) will be needed. > > The code you have here casts the same thing two times, which isn't > > necessary. > > > > > > Thanks. > > Should I resend the patch again? After removing this redundant cast, > it is the same with v2. That patch was pretty busted. This should fix everything up: --- a/kernel/kexec.c~kexec-use-min_t-to-simplify-logic-fix +++ a/kernel/kexec.c @@ -820,8 +820,8 @@ static int kimage_load_normal_segment(st clear_page(ptr); ptr += maddr & ~PAGE_MASK; mchunk = min_t(size_t, mbytes, - (size_t)(PAGE_SIZE - (maddr & ~PAGE_MASK))); - uchunk = min_t(size_t, ubytes, mchunk); + PAGE_SIZE - (maddr & ~PAGE_MASK)); + uchunk = min(ubytes, mchunk); result = copy_from_user(ptr, buf, uchunk); kunmap(page); @@ -868,8 +868,8 @@ static int kimage_load_crash_segment(str ptr = kmap(page); ptr += maddr & ~PAGE_MASK; mchunk = min_t(size_t, mbytes, - (size_t)(PAGE_SIZE - (maddr & ~PAGE_MASK))); - uchunk = min_t(size_t, ubytes, mchunk); + PAGE_SIZE - (maddr & ~PAGE_MASK)); + uchunk = min(ubytes, mchunk); if (mchunk > uchunk) { /* Zero the trailing part of the page */ memset(ptr + uchunk, 0, mchunk - uchunk); @@ -1451,7 +1451,7 @@ void vmcoreinfo_append_str(const char *f r = vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); - r = min_t(size_t, r, vmcoreinfo_max_size - vmcoreinfo_size); + r = min(r, vmcoreinfo_max_size - vmcoreinfo_size); memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r); _