From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752736Ab2BTK2N (ORCPT ); Mon, 20 Feb 2012 05:28:13 -0500 Received: from e5.ny.us.ibm.com ([32.97.182.145]:55789 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364Ab2BTK2K (ORCPT ); Mon, 20 Feb 2012 05:28:10 -0500 Date: Mon, 20 Feb 2012 15:43:37 +0530 From: Srikar Dronamraju To: Ingo Molnar Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, jkenisto@us.ibm.com, a.p.zijlstra@chello.nl, ananth@in.ibm.com, anton@redhat.com, masami.hiramatsu.pt@hitachi.com, acme@infradead.org, oleg@redhat.com, tglx@linutronix.de, Benjamin Herrenschmidt , Josh Stone , linux-tip-commits@vger.kernel.org Subject: Re: [tip:perf/uprobes] uprobes/core: Clean up, refactor and improve the code Message-ID: <20120220101337.GE22680@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20120220060825.GA22680@linux.vnet.ibm.com> <20120220073823.GA30810@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20120220073823.GA30810@elte.hu> User-Agent: Mutt/1.5.20 (2009-06-14) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12022010-5930-0000-0000-00000556C4AB Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ingo Molnar [2012-02-20 08:38:23]: > > * Srikar Dronamraju wrote: > > > The volatiles were added to arch/x86/kernel/kprobes.c because > > of commit 7115e3fcf45 and 315eb8a2a1b. The volatiles are > > required because gcc 4.6 gave a warning about the asm operand > > for test_bit. So the same were added to > > arch/x86/kernel/uprobes.c. > > Seems like a GCC bug - a bogus warning - or does it generate bad > code as well? Yes it is a gcc bug and was fixed by Jakub. As per Josh, only the first long is output if compiled on the buggy gcc. > > In any case, kprobes.c did it correctly, it added the volatile > *and a comment*, pointing out that it's a GCC bug. No such > warning was added to uprobes.c, making the volatile look > entirely spurious. okay. > > So feel free to re-add the volatile in a followup patch, just > make sure the GCC workaround nature is documented. > > Thanks, > > Ingo >