From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from [222.73.24.84] (helo=song.cn.fujitsu.com) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1UACQd-0007OL-BV for kexec@lists.infradead.org; Tue, 26 Feb 2013 04:46:12 +0000 Message-ID: <512C3DA6.8080304@cn.fujitsu.com> Date: Tue, 26 Feb 2013 12:44:22 +0800 From: Zhang Yanfei MIME-Version: 1.0 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> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Andrew Morton Cc: Simon Horman , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Zhang Yanfei , "Eric W. Biederman" 5LqOIDIwMTPlubQwMuaciDI25pelIDA3OjM1LCBBbmRyZXcgTW9ydG9uIOWGmemBkzoKPiBPbiBN b24sIDI1IEZlYiAyMDEzIDA5OjM2OjUxICswOTAwCj4gU2ltb24gSG9ybWFuIDxob3Jtc0B2ZXJn ZS5uZXQuYXU+IHdyb3RlOgo+IAo+PiBPbiBTdW4sIEZlYiAyNCwgMjAxMyBhdCAxMDozNzoyMVBN ICswODAwLCBaaGFuZyBZYW5mZWkgd3JvdGU6Cj4+PiBGcm9tOiBaaGFuZyBZYW5mZWkgPHpoYW5n eWFuZmVpQGNuLmZ1aml0c3UuY29tPgo+Pj4KPj4+IFRoaXMgaXMganVzdCBhIHR3ZWFrOiB1c2lu ZyBtaW5fdCB0byBzaW1wbGlmeSBsb2dpYyBvZiB2YXJpYWJsZQo+Pj4gYXNzaWdubWVudHMuCj4+ Pgo+Pj4gdjI6Cj4+PiAtIFJld3JpdGUgcGF0Y2ggZGVzY3JpcHRpb24gYXMgU2ltb24gc3VnZ2Vz dGVkLgo+Pj4gLSBGaXggYW4gaW5hcHByb3ByaWF0ZSBpZiB0ZXN0IGludHJvZHVjZWQgYnkgdjEu IFRoYW5rcyBTaW1vbi4KPj4KPj4gSGkgWmhhbmcsCj4+Cj4+IHRoYW5rcyBmb3IgdGhlIHVwZGF0 ZS4KPj4KPj4gU2lnbmVkLW9mZi1ieTogU2ltb24gSG9ybWFuIDxob3Jtc0B2ZXJnZS5uZXQuYXU+ Cj4gCj4gU2lnbmVkLW9mZi1ieTogaW1wbGllcyB0aGF0IHlvdSB3ZXJlIGludm9sdmVkIGluIHRo ZSBkZXZlbG9wbWVudCBvcgo+IHBhdGNoIGRlbGl2ZXJ5LiAgV2VyZSB5b3U/ICBJZiBub3QsIGFu IEFja2VkLWJ5IG9yIFJldmlld2VkLWJ5IGlzIG1vcmUKPiBhcHByb3ByaWF0ZS4KPiAKPiBBbHNv LCB0aGUgbmVlZCB0byB1c2UgbWluX3QgcmF0aGVyIHRoYW4gbWluIGlzIGEgc2lnbiB0aGF0IHRo ZSB0eXBlcwo+IGFyZSBzY3Jld2VkIHVwLiAgTGV0J3MgdGFrZSBhIGxvb2suCj4gCj4+Pgo+Pj4g ZGlmZiAtLWdpdCBhL2tlcm5lbC9rZXhlYy5jIGIva2VybmVsL2tleGVjLmMKPj4+IGluZGV4IDI0 MzZmZmMuLmVmZmQ2NTUgMTAwNjQ0Cj4+PiAtLS0gYS9rZXJuZWwva2V4ZWMuYwo+Pj4gKysrIGIv a2VybmVsL2tleGVjLmMKPj4+IEBAIC04MjIsMTMgKzgyMiw4IEBAIHN0YXRpYyBpbnQga2ltYWdl X2xvYWRfbm9ybWFsX3NlZ21lbnQoc3RydWN0IGtpbWFnZSAqaW1hZ2UsCj4+PiAgCQkvKiBTdGFy dCB3aXRoIGEgY2xlYXIgcGFnZSAqLwo+Pj4gIAkJY2xlYXJfcGFnZShwdHIpOwo+Pj4gIAkJcHRy ICs9IG1hZGRyICYgflBBR0VfTUFTSzsKPj4+IC0JCW1jaHVuayA9IFBBR0VfU0laRSAtIChtYWRk ciAmIH5QQUdFX01BU0spOwo+Pj4gLQkJaWYgKG1jaHVuayA+IG1ieXRlcykKPj4+IC0JCQltY2h1 bmsgPSBtYnl0ZXM7Cj4+PiAtCj4+PiAtCQl1Y2h1bmsgPSBtY2h1bms7Cj4+PiAtCQlpZiAodWNo dW5rID4gdWJ5dGVzKQo+Pj4gLQkJCXVjaHVuayA9IHVieXRlczsKPj4+ICsJCW1jaHVuayA9IG1p bl90KHNpemVfdCwgbWJ5dGVzLCBQQUdFX1NJWkUgLSAobWFkZHIgJiB+UEFHRV9NQVNLKSk7Cj4+ PiArCQl1Y2h1bmsgPSBtaW5fdChzaXplX3QsIHVieXRlcywgbWNodW5rKTsKPiAKPiBUaGUgdHlw ZXMgb2YgdWJ5dGVzIGFuZCBtYnl0ZXMgYXJlIGNsZWFybHkgd3JvbmcuICBUaGV5IGFyZSBpbml0 aWFsaXNlZAo+IGZyb20gYSBzaXplX3QgYW5kIHRoZXkgYXJlIG1hbmlwdWxhdGVkIGFsb25nc2lk ZSBzaXplX3Qncy4KCkFoLCB5ZXMuIEkgZGlkbid0IHJlYWxpemUgdGhpcyBiZWZvcmUuCgo+IAo+ IFRoZSB0eXBlcyBvZiBQQUdFX1NJWkUgYW5kIFBBR0VfTUFTSyBhcmUgdmFndWUgLSBpaXJjIHRo ZXkgb25jZSBoYWQKPiBkaWZmZXJlbnQgdHlwZXMgb24gZGlmZmVyZW50IGFyY2hpdGVjdHVyZXMs IHNvIHNvbWUgZm9ybSBvZiBjYXN0aW5nIGlzCj4gdW5hdm9pZGFibGUgaGVyZS4KClllcy4KCj4g Cj4+PiAgCQlyZXN1bHQgPSBjb3B5X2Zyb21fdXNlcihwdHIsIGJ1ZiwgdWNodW5rKTsKPj4+ICAJ CWt1bm1hcChwYWdlKTsKPj4+IEBAIC04NzQsMTMgKzg2OSw5IEBAIHN0YXRpYyBpbnQga2ltYWdl X2xvYWRfY3Jhc2hfc2VnbWVudChzdHJ1Y3Qga2ltYWdlICppbWFnZSwKPj4+ICAJCX0KPj4+ICAJ CXB0ciA9IGttYXAocGFnZSk7Cj4+PiAgCQlwdHIgKz0gbWFkZHIgJiB+UEFHRV9NQVNLOwo+Pj4g LQkJbWNodW5rID0gUEFHRV9TSVpFIC0gKG1hZGRyICYgflBBR0VfTUFTSyk7Cj4+PiAtCQlpZiAo bWNodW5rID4gbWJ5dGVzKQo+Pj4gLQkJCW1jaHVuayA9IG1ieXRlczsKPj4+IC0KPj4+IC0JCXVj aHVuayA9IG1jaHVuazsKPj4+IC0JCWlmICh1Y2h1bmsgPiB1Ynl0ZXMpIHsKPj4+IC0JCQl1Y2h1 bmsgPSB1Ynl0ZXM7Cj4+PiArCQltY2h1bmsgPSBtaW5fdChzaXplX3QsIG1ieXRlcywgUEFHRV9T SVpFIC0gKG1hZGRyICYgflBBR0VfTUFTSykpOwo+Pj4gKwkJdWNodW5rID0gbWluX3Qoc2l6ZV90 LCB1Ynl0ZXMsIG1jaHVuayk7Cj4+PiArCQlpZiAobWNodW5rID4gdWNodW5rKSB7Cj4+PiAgCQkJ LyogWmVybyB0aGUgdHJhaWxpbmcgcGFydCBvZiB0aGUgcGFnZSAqLwo+Pj4gIAkJCW1lbXNldChw dHIgKyB1Y2h1bmssIDAsIG1jaHVuayAtIHVjaHVuayk7Cj4+PiAgCQl9Cj4gCj4gQWdhaW4sIG15 YnRlcyBhbmQgdWJ5dGVzIGhhdmUgdGhlIHdyb25nIHR5cGUuCj4gCj4+PiBAQCAtMTQ2MSw4ICsx NDUyLDcgQEAgdm9pZCB2bWNvcmVpbmZvX2FwcGVuZF9zdHIoY29uc3QgY2hhciAqZm10LCAuLi4p Cj4+PiAgCXIgPSB2c25wcmludGYoYnVmLCBzaXplb2YoYnVmKSwgZm10LCBhcmdzKTsKPj4+ICAJ dmFfZW5kKGFyZ3MpOwo+Pj4gIAo+Pj4gLQlpZiAociArIHZtY29yZWluZm9fc2l6ZSA+IHZtY29y ZWluZm9fbWF4X3NpemUpCj4+PiAtCQlyID0gdm1jb3JlaW5mb19tYXhfc2l6ZSAtIHZtY29yZWlu Zm9fc2l6ZTsKPj4+ICsJciA9IG1pbl90KHNpemVfdCwgciwgdm1jb3JlaW5mb19tYXhfc2l6ZSAt IHZtY29yZWluZm9fc2l6ZSk7Cj4+PiAgCj4+PiAgCW1lbWNweSgmdm1jb3JlaW5mb19kYXRhW3Zt Y29yZWluZm9fc2l6ZV0sIGJ1Ziwgcik7Cj4gCj4gdm1jb3JlaW5mb19tYXhfc2l6ZSBpcyBhIHNp emVfdCBhbmQgdm1jb3JlaW5mb19zaXplIGlzIGEgc2l6ZV90IGFuZAo+IG1lbWNweSdzIGBzaXpl JyBhcmd1bWVudCBpcyBhIHNpemVfdC4gIFRoZXJlZm9yZSB0aGUgdHlwZSBvZiBgcicgc2hvdWxk Cj4gYmUuLi4gIHdoYXQ/ICBpbnQhICBienp6enQuCgp5ZXMuCgpTbyBJIHdpbGwgc3BsaXQgdGhl IHBhdGNoIGludG8gdHdvLCBmaXJzdCBmaXggdGhlIHdyb25nIHR5cGVzIGhlcmUuIFRoZW4KdXNl IG1pbl90IHRvIHNpbXBseSB0aGUgbG9naWMuCgpUaGFua3MKWmhhbmcKCj4gCj4gCj4gX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KPiBrZXhlYyBtYWlsaW5n IGxpc3QKPiBrZXhlY0BsaXN0cy5pbmZyYWRlYWQub3JnCj4gaHR0cDovL2xpc3RzLmluZnJhZGVh ZC5vcmcvbWFpbG1hbi9saXN0aW5mby9rZXhlYwo+IAoKCl9fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fCmtleGVjIG1haWxpbmcgbGlzdAprZXhlY0BsaXN0cy5p bmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8v a2V4ZWMK 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 >