From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754412Ab1K1UCx (ORCPT ); Mon, 28 Nov 2011 15:02:53 -0500 Received: from casper.infradead.org ([85.118.1.10]:59924 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755455Ab1K1UCu convert rfc822-to-8bit (ORCPT ); Mon, 28 Nov 2011 15:02:50 -0500 Message-ID: <1322510552.2921.167.camel@twins> Subject: Re: [PATCH 4/9] ftrace: Add enable/disable ftrace_ops control interface From: Peter Zijlstra To: Steven Rostedt Cc: Jiri Olsa , fweisbec@gmail.com, mingo@redhat.com, paulus@samba.org, acme@ghostprotocols.net, linux-kernel@vger.kernel.org Date: Mon, 28 Nov 2011 21:02:32 +0100 In-Reply-To: <1322508398.17003.9.camel@frodo> References: <1322417074-5834-1-git-send-email-jolsa@redhat.com> <1322417074-5834-5-git-send-email-jolsa@redhat.com> <1322508398.17003.9.camel@frodo> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-11-28 at 14:26 -0500, Steven Rostedt wrote: > > Are jump labels safe in NMI context yet? If not, this will need to wait > till we make it so. I don't think they are, we currently very much rely on that stop_machine() crap. NMIs can go straight through that. I think you can make it work with the stop_machine()-less approach, because then the NMI will trap on the INT3 which will wait for completion, sync and resume the NMI. That of course relies on the NMI vs IRET crap getting sorted. But even then, that's highly arch specific and I'm not sure we can make all archs that support both jump_label and NMIs work.