From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751514Ab0G1FYQ (ORCPT ); Wed, 28 Jul 2010 01:24:16 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:64322 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071Ab0G1FYM (ORCPT ); Wed, 28 Jul 2010 01:24:12 -0400 Message-ID: <4C4FBE2B.6030606@monstr.eu> Date: Wed, 28 Jul 2010 07:20:43 +0200 From: Michal Simek Reply-To: monstr@monstr.eu User-Agent: Thunderbird 2.0.0.22 (X11/20090625) MIME-Version: 1.0 To: Andrew Morton CC: rostedt@goodmis.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@elte.hu, linux-arch@vger.kernel.org Subject: Re: [PATCH] asm-generic: Use raw_local_irq_save/restore instead local_irq_save/restore References: <1274863724-14906-1-git-send-email-monstr@monstr.eu> <1274863724-14906-2-git-send-email-monstr@monstr.eu> <1274884963.22648.245.camel@gandalf.stny.rr.com> <20100526100805.171b3c48.akpm@linux-foundation.org> <4C4D4C2E.8010103@monstr.eu> <20100727161819.cf6feab1.akpm@linux-foundation.org> In-Reply-To: <20100727161819.cf6feab1.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > On Mon, 26 Jul 2010 10:49:50 +0200 > Michal Simek wrote: > >> start/stop_critical_timing function for preemptirqsoff, preemptoff >> and irqsoff tracers contains atomic_inc and atomic_dec operations. >> >> Atomic operations used local_irq_save/restore macros to ensure >> atomic access but they are traced by the same function which is causing >> recursion problem. >> >> The reason is when these tracers are turn ON then local_irq_save/restore >> macros are changed in include/linux/irqflags.h to call trace_hardirqs_on/off >> which call start/stop_critical_timing. >> >> Microblaze was affected because use generic atomic implementation. > > Seems that this will also affect blackfin, mn10300 and score. I guess > they aren't supporting tracing yet? If they uses asm-generic/atomic.h, then yes. It seems to me that Blackfin uses own asm/atomic.h. nm10300 and score are the same case as Microblaze. In include/linux/irqflags.h is written this commentary. /* * The local_irq_*() APIs are equal to the raw_local_irq*() * if !TRACE_IRQFLAGS. */ If architecture doesn't enable TRACE_IRQFLAGS then there is no difference in behavior. If yes and use asm-generic/atomic.h code, then IRQFLAG tracer freeze because it is traced part of irqsoff tracer because of recursion as is describe in patch description. > >> Signed-off-by: Michal Simek >> Acked-by: Steven Rostedt >> Signed-off-by: Andrew Morton > > hm, I wonder how my signoff got there. Doesn't matter. http://lkml.org/lkml/2010/5/26/364 Michal -- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian