From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753666AbaAGSbW (ORCPT ); Tue, 7 Jan 2014 13:31:22 -0500 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.226]:22757 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752618AbaAGSbO (ORCPT ); Tue, 7 Jan 2014 13:31:14 -0500 Date: Tue, 7 Jan 2014 13:31:11 -0500 From: Steven Rostedt To: Dave Martin Cc: Arnd Bergmann , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" , sahara , Keun-O Park , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 19/19] [INCOMPLETE] ARM: make return_address available for ARM_UNWIND Message-ID: <20140107133111.0fe49c21@gandalf.local.home> In-Reply-To: <20140107163629.GC3350@e103592.cambridge.arm.com> References: <1359123276-15833-1-git-send-email-arnd@arndb.de> <201401071533.35309.arnd@arndb.de> <20140107144130.GJ27432@n2100.arm.linux.org.uk> <4325142.7drL5ndxN9@wuerfel> <20140107163629.GC3350@e103592.cambridge.arm.com> X-Mailer: Claws Mail 3.9.2 (GTK+ 2.24.22; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 7 Jan 2014 16:36:29 +0000 Dave Martin wrote: > My other concern was that we might end up in a recursive trace due to > the use of non-notrace core functions in the unwinder. But I seem to > remember Steve Rostedt saying the the tracer guards against recursive > invocation nowadays -- if so, that shouldn't be a problem. I guess it matters what type of tracing you are talking about. The function tracer protects against all recursive contexts (normal, softirq, irq and NMI) and so does the ring buffer (same levels). Those may be the only ones that matter, as things like events shouldn't recurse, unless you have an event in the unwinder itself. But that's where you take the doctor's advice of "don't do that". -- Steve