From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759566Ab3BZEqK (ORCPT ); Mon, 25 Feb 2013 23:46:10 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:10367 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1759187Ab3BZEqG convert rfc822-to-8bit (ORCPT ); Mon, 25 Feb 2013 23:46:06 -0500 X-IronPort-AV: E=Sophos;i="4.84,737,1355068800"; d="scan'208";a="6769063" Message-ID: <512C3DA6.8080304@cn.fujitsu.com> Date: Tue, 26 Feb 2013 12:44:22 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.8) Gecko/20121012 Thunderbird/10.0.8 MIME-Version: 1.0 To: Andrew Morton CC: Simon Horman , "linux-kernel@vger.kernel.org" , "kexec@lists.infradead.org" , "Eric W. Biederman" , Zhang Yanfei Subject: Re: [PATCH v2] kexec: Use min_t to simplify logic References: <512A25A1.4040002@gmail.com> <20130225003651.GD17964@verge.net.au> <20130225153554.19cde4b4.akpm@linux-foundation.org> In-Reply-To: <20130225153554.19cde4b4.akpm@linux-foundation.org> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/02/26 12:45:13, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/02/26 12:45:14 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2013年02月26日 07:35, Andrew Morton 写道: > On Mon, 25 Feb 2013 09:36:51 +0900 > Simon Horman wrote: > >> On Sun, Feb 24, 2013 at 10:37:21PM +0800, Zhang Yanfei wrote: >>> From: Zhang Yanfei >>> >>> This is just a tweak: using min_t to simplify logic of variable >>> assignments. >>> >>> v2: >>> - Rewrite patch description as Simon suggested. >>> - Fix an inappropriate if test introduced by v1. Thanks Simon. >> >> Hi Zhang, >> >> thanks for the update. >> >> Signed-off-by: Simon Horman > > Signed-off-by: implies that you were involved in the development or > patch delivery. Were you? If not, an Acked-by or Reviewed-by is more > appropriate. > > Also, the need to use min_t rather than min is a sign that the types > are screwed up. Let's take a look. > >>> >>> diff --git a/kernel/kexec.c b/kernel/kexec.c >>> index 2436ffc..effd655 100644 >>> --- a/kernel/kexec.c >>> +++ b/kernel/kexec.c >>> @@ -822,13 +822,8 @@ static int kimage_load_normal_segment(struct kimage *image, >>> /* Start with a clear page */ >>> clear_page(ptr); >>> ptr += maddr & ~PAGE_MASK; >>> - mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK); >>> - if (mchunk > mbytes) >>> - mchunk = mbytes; >>> - >>> - uchunk = mchunk; >>> - if (uchunk > ubytes) >>> - uchunk = ubytes; >>> + mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK)); >>> + uchunk = min_t(size_t, ubytes, mchunk); > > The types of ubytes and mbytes are clearly wrong. They are initialised > from a size_t and they are manipulated alongside size_t's. Ah, yes. I didn't realize this before. > > 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. Yes. > >>> result = copy_from_user(ptr, buf, uchunk); >>> kunmap(page); >>> @@ -874,13 +869,9 @@ static int kimage_load_crash_segment(struct kimage *image, >>> } >>> ptr = kmap(page); >>> ptr += maddr & ~PAGE_MASK; >>> - mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK); >>> - if (mchunk > mbytes) >>> - mchunk = mbytes; >>> - >>> - uchunk = mchunk; >>> - if (uchunk > ubytes) { >>> - uchunk = ubytes; >>> + mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK)); >>> + uchunk = min_t(size_t, ubytes, mchunk); >>> + if (mchunk > uchunk) { >>> /* Zero the trailing part of the page */ >>> memset(ptr + uchunk, 0, mchunk - uchunk); >>> } > > Again, mybtes and ubytes have the wrong type. > >>> @@ -1461,8 +1452,7 @@ void vmcoreinfo_append_str(const char *fmt, ...) >>> r = vsnprintf(buf, sizeof(buf), fmt, args); >>> va_end(args); >>> >>> - if (r + vmcoreinfo_size > vmcoreinfo_max_size) >>> - r = vmcoreinfo_max_size - vmcoreinfo_size; >>> + r = min_t(size_t, r, vmcoreinfo_max_size - vmcoreinfo_size); >>> >>> memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r); > > vmcoreinfo_max_size is a size_t and vmcoreinfo_size is a size_t and > memcpy's `size' argument is a size_t. Therefore the type of `r' should > be... what? int! bzzzzt. yes. So I will split the patch into two, first fix the wrong types here. Then use min_t to simply the logic. Thanks Zhang > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec >