From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753669Ab2DZN3n (ORCPT ); Thu, 26 Apr 2012 09:29:43 -0400 Received: from seven.medozas.de ([188.40.89.202]:56141 "EHLO seven.medozas.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751869Ab2DZN3m (ORCPT ); Thu, 26 Apr 2012 09:29:42 -0400 Date: Thu, 26 Apr 2012 15:29:38 +0200 (CEST) From: Jan Engelhardt To: Peter Zijlstra cc: "Paul E. McKenney" , linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, patches@linaro.org Subject: Re: [PATCH RFC tip/core/rcu 5/6] rcu: Make __kfree_rcu() less dependent on compiler choices In-Reply-To: <1335444509.13683.13.camel@twins> Message-ID: References: <20120423164159.GA13819@linux.vnet.ibm.com> <1335199347-13926-1-git-send-email-paulmck@linux.vnet.ibm.com> <1335199347-13926-5-git-send-email-paulmck@linux.vnet.ibm.com> <1335444509.13683.13.camel@twins> User-Agent: Alpine 2.01 (LNX 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 2012-04-26 14:48, Peter Zijlstra wrote: >On Mon, 2012-04-23 at 09:42 -0700, Paul E. McKenney wrote: >> Currently, __kfree_rcu() is implemented as an inline function, and >> contains a BUILD_BUG_ON() that malfunctions if __kfree_rcu() is compiled >> as an out-of-line function. Unfortunately, there are compiler settings >> (e.g., -O0) that can result in __kfree_rcu() being compiled out of line, >> resulting in annoying build breakage. This commit therefore converts >> both __kfree_rcu() and __is_kfree_rcu_offset() from inline functions to >> macros to prevent such misbehavior on the part of the compiler. > >The kernel very explicitly doesn't support being compiled with -O0, so >this is a non-issue, I think you can make it work if you add >-finline-functions. > >I'd drop this, either make the entire kernel compile or don't bother. It was not originally meant to make the entire kernel compile with -O0, but only select modules/.c files. That, or __always_inline just does not always inline.