From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-da0-f47.google.com ([209.85.210.47]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1U9bBI-0001c2-4S for kexec@lists.infradead.org; Sun, 24 Feb 2013 12:59:53 +0000 Received: by mail-da0-f47.google.com with SMTP id s35so1068939dak.20 for ; Sun, 24 Feb 2013 04:59:51 -0800 (PST) Message-ID: <512A0EBB.30406@gmail.com> Date: Sun, 24 Feb 2013 20:59:39 +0800 From: Zhang Yanfei MIME-Version: 1.0 Subject: Re: [PATCH] kexec: use min_t/max_t to avoid 'if (foo == bar)' thing References: <512990F4.3030203@cn.fujitsu.com> <20130224105533.GG18639@verge.net.au> In-Reply-To: <20130224105533.GG18639@verge.net.au> 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: Simon Horman Cc: "kexec@lists.infradead.org" , Andrew Morton , Zhang Yanfei , "Eric W. Biederman" , "linux-kernel@vger.kernel.org" 5LqOIDIwMTPlubQwMuaciDI05pelIDE4OjU1LCBTaW1vbiBIb3JtYW4g5YaZ6YGTOgo+IE9uIFN1 biwgRmViIDI0LCAyMDEzIGF0IDEyOjAzOjAwUE0gKzA4MDAsIFpoYW5nIFlhbmZlaSB3cm90ZToK Pj4gVGhpcyBpcyBqdXN0IGEgdHdlYWs6IHVzaW5nIG1pbl90L21heF90IHRvIGF2b2lkIGBpZiAo Zm9vID0gYmFyKScgdGhpbmcuCj4gCj4gLSBzLz0vPT0vOyBzL1svXW1heF90Ly8KPiAKPiAKPiBC dXQgaW4gYW55IGNhc2UgdGhlIGNoYW5nZSBpcyBtb3JlIHRoYW4gdGhhdC4KPiBJJ2QgYmUgaGFw cGllciB3aXRoIHNvbWV0aGluZyBsaWtlOgo+IAo+IAlrZXhlYzogVXNlIG1pbl90IHRvIHNpbXBs aWZ5IGxvZ2ljCgpIbW0sIGFncmVlZC4KCj4gCj4+IENjOiAiRXJpYyBXLiBCaWVkZXJtYW4iIDxl YmllZGVybUB4bWlzc2lvbi5jb20+Cj4+IENjOiBBbmRyZXcgTW9ydG9uIDxha3BtQGxpbnV4LWZv dW5kYXRpb24ub3JnPgo+PiBDYzogU2ltb24gSG9ybWFuIDxob3Jtc0B2ZXJnZS5uZXQuYXU+Cj4+ IFNpZ25lZC1vZmYtYnk6IFpoYW5nIFlhbmZlaSA8emhhbmd5YW5mZWlAY24uZnVqaXRzdS5jb20+ Cj4+IC0tLQo+PiAga2VybmVsL2tleGVjLmMgfCAgIDIwICsrKysrLS0tLS0tLS0tLS0tLS0tCj4+ ICAxIGZpbGVzIGNoYW5nZWQsIDUgaW5zZXJ0aW9ucygrKSwgMTUgZGVsZXRpb25zKC0pCj4+Cj4+ IGRpZmYgLS1naXQgYS9rZXJuZWwva2V4ZWMuYyBiL2tlcm5lbC9rZXhlYy5jCj4+IGluZGV4IDI0 MzZmZmMuLjA2NWRiODcgMTAwNjQ0Cj4+IC0tLSBhL2tlcm5lbC9rZXhlYy5jCj4+ICsrKyBiL2tl cm5lbC9rZXhlYy5jCj4+IEBAIC04MjIsMTMgKzgyMiw4IEBAIHN0YXRpYyBpbnQga2ltYWdlX2xv YWRfbm9ybWFsX3NlZ21lbnQoc3RydWN0IGtpbWFnZSAqaW1hZ2UsCj4+ICAJCS8qIFN0YXJ0IHdp dGggYSBjbGVhciBwYWdlICovCj4+ICAJCWNsZWFyX3BhZ2UocHRyKTsKPj4gIAkJcHRyICs9IG1h ZGRyICYgflBBR0VfTUFTSzsKPj4gLQkJbWNodW5rID0gUEFHRV9TSVpFIC0gKG1hZGRyICYgflBB R0VfTUFTSyk7Cj4+IC0JCWlmIChtY2h1bmsgPiBtYnl0ZXMpCj4+IC0JCQltY2h1bmsgPSBtYnl0 ZXM7Cj4+IC0KPj4gLQkJdWNodW5rID0gbWNodW5rOwo+PiAtCQlpZiAodWNodW5rID4gdWJ5dGVz KQo+PiAtCQkJdWNodW5rID0gdWJ5dGVzOwo+PiArCQltY2h1bmsgPSBtaW5fdChzaXplX3QsIG1i eXRlcywgUEFHRV9TSVpFIC0gKG1hZGRyICYgflBBR0VfTUFTSykpOwo+PiArCQl1Y2h1bmsgPSBt aW5fdChzaXplX3QsIHVieXRlcywgbWNodW5rKTsKPj4gIAo+PiAgCQlyZXN1bHQgPSBjb3B5X2Zy b21fdXNlcihwdHIsIGJ1ZiwgdWNodW5rKTsKPj4gIAkJa3VubWFwKHBhZ2UpOwo+PiBAQCAtODc0 LDEzICs4NjksOSBAQCBzdGF0aWMgaW50IGtpbWFnZV9sb2FkX2NyYXNoX3NlZ21lbnQoc3RydWN0 IGtpbWFnZSAqaW1hZ2UsCj4+ICAJCX0KPj4gIAkJcHRyID0ga21hcChwYWdlKTsKPj4gIAkJcHRy ICs9IG1hZGRyICYgflBBR0VfTUFTSzsKPj4gLQkJbWNodW5rID0gUEFHRV9TSVpFIC0gKG1hZGRy ICYgflBBR0VfTUFTSyk7Cj4+IC0JCWlmIChtY2h1bmsgPiBtYnl0ZXMpCj4+IC0JCQltY2h1bmsg PSBtYnl0ZXM7Cj4+IC0KPj4gLQkJdWNodW5rID0gbWNodW5rOwo+PiArCQltY2h1bmsgPSBtaW5f dChzaXplX3QsIG1ieXRlcywgUEFHRV9TSVpFIC0gKG1hZGRyICYgflBBR0VfTUFTSykpOwo+PiAr CQl1Y2h1bmsgPSBtaW5fdChzaXplX3QsIHVieXRlcywgbWNodW5rKTsKPiAKPiBUaGUgbGluZSBh Ym92ZSBtZWFucyB0aGF0IHVjaHVuayBjYW4gbm93IG5ldmVyIGJlIGdyZWF0ZXIgdGhhbiB1Ynl0 ZXMuCj4gCj4+ICAJCWlmICh1Y2h1bmsgPiB1Ynl0ZXMpIHsKPiAKPiBTbyB0aGUgZm9sbG93aW5n IHNlZW1zIG1vcmUgYXBwcm9wcmlhdGUgdG8gbWU6Cj4gCj4gCQlpZiAobWNodW5rID4gdWNodW5r KSB7CgpPb3BzLCB0aGlzIGlzIHJlYWxseSBhIG1pc3Rha2UuIFRoYW5rcy4KCkkgd2lsbCBzZW5k IHRoZSB2MiBwYXRjaC4KCj4gCj4gCj4+IC0JCQl1Y2h1bmsgPSB1Ynl0ZXM7Cj4+ICAJCQkvKiBa ZXJvIHRoZSB0cmFpbGluZyBwYXJ0IG9mIHRoZSBwYWdlICovCj4+ICAJCQltZW1zZXQocHRyICsg dWNodW5rLCAwLCBtY2h1bmsgLSB1Y2h1bmspOwo+PiAgCQl9Cj4+IEBAIC0xNDYxLDggKzE0NTIs NyBAQCB2b2lkIHZtY29yZWluZm9fYXBwZW5kX3N0cihjb25zdCBjaGFyICpmbXQsIC4uLikKPj4g IAlyID0gdnNucHJpbnRmKGJ1Ziwgc2l6ZW9mKGJ1ZiksIGZtdCwgYXJncyk7Cj4+ICAJdmFfZW5k KGFyZ3MpOwo+PiAgCj4+IC0JaWYgKHIgKyB2bWNvcmVpbmZvX3NpemUgPiB2bWNvcmVpbmZvX21h eF9zaXplKQo+PiAtCQlyID0gdm1jb3JlaW5mb19tYXhfc2l6ZSAtIHZtY29yZWluZm9fc2l6ZTsK Pj4gKwlyID0gbWluX3Qoc2l6ZV90LCByLCB2bWNvcmVpbmZvX21heF9zaXplIC0gdm1jb3JlaW5m b19zaXplKTsKPj4gIAo+PiAgCW1lbWNweSgmdm1jb3JlaW5mb19kYXRhW3ZtY29yZWluZm9fc2l6 ZV0sIGJ1Ziwgcik7Cj4+ICAKPj4gLS0gCj4+IDEuNy4xCj4+Cj4gLS0KPiBUbyB1bnN1YnNjcmli ZSBmcm9tIHRoaXMgbGlzdDogc2VuZCB0aGUgbGluZSAidW5zdWJzY3JpYmUgbGludXgta2VybmVs IiBpbgo+IHRoZSBib2R5IG9mIGEgbWVzc2FnZSB0byBtYWpvcmRvbW9Admdlci5rZXJuZWwub3Jn Cj4gTW9yZSBtYWpvcmRvbW8gaW5mbyBhdCAgaHR0cDovL3ZnZXIua2VybmVsLm9yZy9tYWpvcmRv bW8taW5mby5odG1sCj4gUGxlYXNlIHJlYWQgdGhlIEZBUSBhdCAgaHR0cDovL3d3dy50dXgub3Jn L2xrbWwvCgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18K a2V4ZWMgbWFpbGluZyBsaXN0CmtleGVjQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3Rz LmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9rZXhlYwo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757988Ab3BXM7x (ORCPT ); Sun, 24 Feb 2013 07:59:53 -0500 Received: from mail-da0-f51.google.com ([209.85.210.51]:56355 "EHLO mail-da0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755551Ab3BXM7v (ORCPT ); Sun, 24 Feb 2013 07:59:51 -0500 Message-ID: <512A0EBB.30406@gmail.com> Date: Sun, 24 Feb 2013 20:59:39 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.5) Gecko/20120607 Thunderbird/10.0.5 MIME-Version: 1.0 To: Simon Horman CC: Zhang Yanfei , "Eric W. Biederman" , Andrew Morton , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] kexec: use min_t/max_t to avoid 'if (foo == bar)' thing References: <512990F4.3030203@cn.fujitsu.com> <20130224105533.GG18639@verge.net.au> In-Reply-To: <20130224105533.GG18639@verge.net.au> 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24日 18:55, Simon Horman 写道: > On Sun, Feb 24, 2013 at 12:03:00PM +0800, Zhang Yanfei wrote: >> This is just a tweak: using min_t/max_t to avoid `if (foo = bar)' thing. > > - s/=/==/; s/[/]max_t// > > > But in any case the change is more than that. > I'd be happier with something like: > > kexec: Use min_t to simplify logic Hmm, agreed. > >> Cc: "Eric W. Biederman" >> Cc: Andrew Morton >> Cc: Simon Horman >> Signed-off-by: Zhang Yanfei >> --- >> kernel/kexec.c | 20 +++++--------------- >> 1 files changed, 5 insertions(+), 15 deletions(-) >> >> diff --git a/kernel/kexec.c b/kernel/kexec.c >> index 2436ffc..065db87 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); >> >> 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; >> + mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK)); >> + uchunk = min_t(size_t, ubytes, mchunk); > > The line above means that uchunk can now never be greater than ubytes. > >> if (uchunk > ubytes) { > > So the following seems more appropriate to me: > > if (mchunk > uchunk) { Oops, this is really a mistake. Thanks. I will send the v2 patch. > > >> - uchunk = ubytes; >> /* Zero the trailing part of the page */ >> memset(ptr + uchunk, 0, mchunk - uchunk); >> } >> @@ -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); >> >> -- >> 1.7.1 >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/