From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751209AbdFAPDq (ORCPT ); Thu, 1 Jun 2017 11:03:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51598 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751096AbdFAPDp (ORCPT ); Thu, 1 Jun 2017 11:03:45 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3476D1A6749 Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jpoimboe@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 3476D1A6749 Date: Thu, 1 Jun 2017 10:03:39 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Linus Torvalds , Andy Lutomirski , Jiri Slaby , Ingo Molnar , "H. Peter Anvin" Subject: Re: [RFC PATCH 10/10] x86/unwind: add undwarf unwinder Message-ID: <20170601150339.q3yalx5kshuligaj@treble> References: <89552d4047e5aed843f7b6a54277f9af62da6a82.1496293620.git.jpoimboe@redhat.com> <20170601121356.5yoeq74el77sewoo@hirez.programming.kicks-ass.net> <20170601123609.ku5zq2huhlneq2dn@treble> <20170601131204.odhgktimjz6czdyu@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170601131204.odhgktimjz6czdyu@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 01 Jun 2017 15:03:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 01, 2017 at 03:12:04PM +0200, Peter Zijlstra wrote: > > Based on your previous comment I was thinking I would disable preemption > > for the entire unwind_next_frame() step, but not *between* steps. I > > suppose we could require the unwind caller to disable preemption but I'd > > like to avoid that if possible. > > Right, keeping it disabled across a frame should be ok I suppose. But then we'd either have to require the unwind user to explicitly disable preemption, or we'd need to add a new unwind_end() interface which the caller would be required to use when they're done unwinding. Neither is ideal. -- Josh