From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756642Ab0DUVAA (ORCPT ); Wed, 21 Apr 2010 17:00:00 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:59776 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755034Ab0DUU76 (ORCPT ); Wed, 21 Apr 2010 16:59:58 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=paAL4ohm/ALP3pqg1fTygIW3hUq78uac8SEXJvOBwQ0Muqz8p5FZerw3cNOjmCMcx9 Rj3TkIm6QiCT1IvYxQDwsftPgE6aO/Avy/S86n8tCf//F0r5v8YmlLzi/d12IIsAHGJg pkJouUzVCu0eDHL6vmgzGoLhuqP1visPIXE0Q= Date: Wed, 21 Apr 2010 23:00:04 +0200 From: Frederic Weisbecker To: Don Zickus Cc: mingo@elte.hu, peterz@infradead.org, gorcunov@gmail.com, aris@redhat.com, linux-kernel@vger.kernel.org, randy.dunlap@oracle.com Subject: Re: [PATCH 5/6] [x86] watchdog: move trigger_all_cpu_backtrace to its own die_notifier Message-ID: <20100421210003.GC8677@nowhere> References: <1271777043-3807-1-git-send-email-dzickus@redhat.com> <1271777043-3807-6-git-send-email-dzickus@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1271777043-3807-6-git-send-email-dzickus@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 20, 2010 at 11:24:02AM -0400, Don Zickus wrote: > As part of the transition of the nmi watchdog to something more generic, > the trigger_all_cpu_backtrace code is getting left behind. Put it in its > own die_notifier so it can still be used. > > Signed-off-by: Don Zickus > --- > arch/x86/kernel/apic/hw_nmi.c | 65 ++++++++++++++++++++++++++++++++--------- > 1 files changed, 51 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c > index 79425f9..19d3435 100644 > --- a/arch/x86/kernel/apic/hw_nmi.c > +++ b/arch/x86/kernel/apic/hw_nmi.c > @@ -17,6 +17,10 @@ > #include > #include > #include > +#include > +#include > +#include > + > > #include > #include > @@ -54,20 +58,6 @@ int hw_nmi_is_cpu_stuck(struct pt_regs *regs) > unsigned int sum; > int cpu = smp_processor_id(); > > - /* FIXME: cheap hack for this check, probably should get its own > - * die_notifier handler > - */ > - if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { > - static DEFINE_SPINLOCK(lock); /* Serialise the printks */ > - > - spin_lock(&lock); > - printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu); > - show_regs(regs); > - dump_stack(); > - spin_unlock(&lock); > - cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); > - } > - > /* if we are doing an mce, just assume the cpu is not stuck */ > /* Could check oops_in_progress here too, but it's safer not to */ > if (mce_in_progress()) > @@ -109,6 +99,53 @@ void arch_trigger_all_cpu_backtrace(void) > mdelay(1); > } > } > + > +static int __kprobes > +arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self, > + unsigned long cmd, void *__args) > +{ > + struct die_args *args = __args; > + struct pt_regs *regs; > + int cpu = smp_processor_id(); > + > + switch (cmd) { > + case DIE_NMI: > + case DIE_NMI_IPI: > + break; > + > + default: > + return NOTIFY_DONE; > + } > + > + regs = args->regs; > + > + if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { > + static DEFINE_SPINLOCK(lock); /* Serialise the printks */ > + > + spin_lock(&lock); This should be an arch_spin_lock(), so that it won't sleep with rt mutex. In fact this whole function can be moved to generic code, right? > + printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu); > + show_regs(regs); > + dump_stack(); > + spin_unlock(&lock); > + cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); > + return NOTIFY_STOP; > + } > + > + return NOTIFY_DONE; > +} > + > +static __read_mostly struct notifier_block backtrace_notifier = { > + .notifier_call = arch_trigger_all_cpu_backtrace_handler, > + .next = NULL, > + .priority = 1 > +}; > + > +static int __init register_trigger_all_cpu_backtrace(void) > +{ > + register_die_notifier(&backtrace_notifier); > + return 0; > +} > +early_initcall(register_trigger_all_cpu_backtrace); > #endif > > /* STUB calls to mimic old nmi_watchdog behaviour */ > -- > 1.6.5.2 >