Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753924AbYJVLUm (ORCPT ); Wed, 22 Oct 2008 07:20:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751894AbYJVLUe (ORCPT ); Wed, 22 Oct 2008 07:20:34 -0400 Received: from charlotte.tuxdriver.com ([70.61.120.58]:53850 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751878AbYJVLUe (ORCPT ); Wed, 22 Oct 2008 07:20:34 -0400 Date: Wed, 22 Oct 2008 07:18:25 -0400 From: Neil Horman To: Alexander van Heukelum Cc: Ingo Molnar , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, vgoyal@redhat.com, hbabu@us.ibm.com, hpa@zytor.com, akpm@linux-foundation.org, ebiederm@xmission.com, tglx@linutronix.de Subject: Re: [PATCH 5/7] i386, dumpstack: use x86_64's method to account die_nest_count Message-ID: <20081022111825.GF18951@hmsreliant.think-freely.org> References: <1224669614-25863-1-git-send-email-heukelum@fastmail.fm> <1224669614-25863-2-git-send-email-heukelum@fastmail.fm> <1224669614-25863-3-git-send-email-heukelum@fastmail.fm> <1224669614-25863-4-git-send-email-heukelum@fastmail.fm> <1224669614-25863-5-git-send-email-heukelum@fastmail.fm> <1224669614-25863-6-git-send-email-heukelum@fastmail.fm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1224669614-25863-6-git-send-email-heukelum@fastmail.fm> User-Agent: Mutt/1.5.18 (2008-05-17) X-Spam-Score: -1.4 (-) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2542 Lines: 87 On Wed, Oct 22, 2008 at 12:00:12PM +0200, Alexander van Heukelum wrote: > oops_begin/oops_end should always be used in pairs. On x86_64 > oops_begin increments die_nest_count, and oops_end decrements > die_nest_count. Doing this makes oops_begin and oops_end equal > to the x86_64 versions. > > Signed-off-by: Alexander van Heukelum Acked-by: Neil Horman > --- > arch/x86/kernel/dumpstack_32.c | 29 +++++++++++++++++------------ > 1 files changed, 17 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c > index a29b88f..7c7d691 100644 > --- a/arch/x86/kernel/dumpstack_32.c > +++ b/arch/x86/kernel/dumpstack_32.c > @@ -289,21 +289,24 @@ static unsigned int die_nest_count; > > unsigned __kprobes long oops_begin(void) > { > + int cpu; > unsigned long flags; > > oops_enter(); > > - if (die_owner != raw_smp_processor_id()) { > - console_verbose(); > - raw_local_irq_save(flags); > - __raw_spin_lock(&die_lock); > - die_owner = smp_processor_id(); > - die_nest_count = 0; > - bust_spinlocks(1); > - } else { > - raw_local_irq_save(flags); > + /* racy, but better than risking deadlock. */ > + raw_local_irq_save(flags); > + cpu = smp_processor_id(); > + if (!__raw_spin_trylock(&die_lock)) { > + if (cpu == die_owner) > + /* nested oops. should stop eventually */; > + else > + __raw_spin_lock(&die_lock); > } > die_nest_count++; > + die_owner = cpu; > + console_verbose(); > + bust_spinlocks(1); > return flags; > } > > @@ -315,13 +318,15 @@ void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr) > bust_spinlocks(0); > die_owner = -1; > add_taint(TAINT_DIE); > - __raw_spin_unlock(&die_lock); > + die_nest_count--; > + if (!die_nest_count) > + /* Nest count reaches zero, release the lock. */ > + __raw_spin_unlock(&die_lock); > raw_local_irq_restore(flags); > - > oops_exit(); > + > if (!signr) > return; > - > if (in_interrupt()) > panic("Fatal exception in interrupt"); > if (panic_on_oops) > -- > 1.5.4.3 > > -- /**************************************************** * Neil Horman * Software Engineer, Red Hat ****************************************************/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/