From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754337AbZCLMQH (ORCPT ); Thu, 12 Mar 2009 08:16:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752918AbZCLMPz (ORCPT ); Thu, 12 Mar 2009 08:15:55 -0400 Received: from vpn.id2.novell.com ([195.33.99.129]:36650 "EHLO vpn.id2.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752383AbZCLMPy convert rfc822-to-8bit (ORCPT ); Thu, 12 Mar 2009 08:15:54 -0400 Message-Id: <49B90B31.76E4.0078.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 8.0.0 Date: Thu, 12 Mar 2009 12:16:33 +0000 From: "Jan Beulich" To: Cc: "Andi Kleen" Subject: [PATCH] eliminate spurious pointless WARN_ON()s Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Namely during early boot, the panic() or BUG() paths may end up in smp_call_function_*() with just a single online CPU. In that situation the warnings generated are not only meaningless, but also result in relevant output being cluttered. Therefore, defer the WARN_ON() checks until after the (unaffected from the problem that is being attempted to be detected here) cases have been handled. Signed-off-by: Jan Beulich Cc: Andi Kleen --- kernel/smp.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- linux-2.6.29-rc7/kernel/smp.c 2009-03-04 09:11:00.000000000 +0100 +++ 2.6.29-rc7-smp-call-defer-warn/kernel/smp.c 2009-02-13 12:17:02.000000000 +0100 @@ -222,9 +222,6 @@ int smp_call_function_single(int cpu, vo int me = get_cpu(); int err = 0; - /* Can deadlock when called with interrupts disabled */ - WARN_ON(irqs_disabled()); - if (cpu == me) { local_irq_save(flags); func(info); @@ -232,6 +229,9 @@ int smp_call_function_single(int cpu, vo } else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { struct call_single_data *data; + /* Can deadlock when called with interrupts disabled */ + WARN_ON(irqs_disabled()); + if (!wait) { /* * We are calling a function on a single CPU @@ -325,9 +325,6 @@ void smp_call_function_many(const struct unsigned long flags; int cpu, next_cpu; - /* Can deadlock when called with interrupts disabled */ - WARN_ON(irqs_disabled()); - /* So, what's a CPU they want? Ignoring this one. */ cpu = cpumask_first_and(mask, cpu_online_mask); if (cpu == smp_processor_id()) @@ -347,6 +344,9 @@ void smp_call_function_many(const struct return; } + /* Can deadlock when called with interrupts disabled */ + WARN_ON(irqs_disabled()); + data = kmalloc(sizeof(*data) + cpumask_size(), GFP_ATOMIC); if (unlikely(!data)) { /* Slow path. */