Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755376AbaDVJdK (ORCPT ); Tue, 22 Apr 2014 05:33:10 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:13495 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754531AbaDVJcy (ORCPT ); Tue, 22 Apr 2014 05:32:54 -0400 Message-ID: <53563709.2000408@huawei.com> Date: Tue, 22 Apr 2014 17:31:53 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Jianyu Zhan CC: Ingo Molnar , , , , , LKML Subject: Re: [PATCH] perf-event/cgroup: explicitly init the early_init field References: <1398144517-9496-1-git-send-email-nasa4836@gmail.com> <20140422060654.GB9133@gmail.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.18.230] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/4/22 15:12, Jianyu Zhan wrote: > On Tue, Apr 22, 2014 at 2:06 PM, Ingo Molnar wrote: >> How can that field ever be nonzero? >> >> I.e. under what exact circumstances does this patch make sense? > > Hi, Ingo, > > More explanation. > > Sure, for this global variable struct, if not initailized, its all > fields will be initialized > to 0 or null(depending on its type). The point here is no to deprive > the rights of compiler/linker of doing this initialization, it is mainly for > documentation reason. Actually this field's value would affect how ->css_alloc > should implemented. > > Concretely, if early_init is nonzero, then ->css_alloc *must not* call kzalloc, > because in cgroup implementation, ->css_alloc will be called earlier before > mm_init(). > > I don't think that the value of one field(early_init) has a so subtle > restrition on the another field(css_alloc) is a good thing, > but since > it is there, > docment it should be needed. > > I could resend the patch with more comment. > nack As I said in another mail thread, this change makes no sense. -- 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/