From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932385AbaGIRK5 (ORCPT ); Wed, 9 Jul 2014 13:10:57 -0400 Received: from mail-pd0-f202.google.com ([209.85.192.202]:47985 "EHLO mail-pd0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756613AbaGIRJn (ORCPT ); Wed, 9 Jul 2014 13:09:43 -0400 From: Havard Skinnemoen To: Tony Luck , Borislav Petkov Cc: linux-kernel@vger.kernel.org, Ewout van Bekkum , Havard Skinnemoen Subject: [PATCH 6/6] x86-mce: ensure the MCP timer is not already set in the mce_timer_fn. Date: Wed, 9 Jul 2014 10:09:26 -0700 Message-Id: <1404925766-32253-7-git-send-email-hskinnemoen@google.com> X-Mailer: git-send-email 2.0.0.526.g5318336 In-Reply-To: <1404925766-32253-1-git-send-email-hskinnemoen@google.com> References: <1404925766-32253-1-git-send-email-hskinnemoen@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ewout van Bekkum The machine check poll timer function, mce_timer_fn(), did not check whether the MCP timer had already been set in case the function was preempted by an interrupt. A CMCI interrupt could preempt this function and enable the MCP timer through mce_timer_kick(). The race condition was resolved by disabling interrupts during the mce_timer_fn() function and by verifying the timer isn't already set before starting the timer. Signed-off-by: Ewout van Bekkum Signed-off-by: Havard Skinnemoen --- arch/x86/kernel/cpu/mcheck/mce.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 1587b18..c5e40cb 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1310,10 +1310,13 @@ static void mce_timer_fn(unsigned long data) { struct timer_list *t = &__get_cpu_var(mce_timer); unsigned long iv; + unsigned long flags; int notify; WARN_ON(smp_processor_id() != data); + /* Ensure a CMCI interrupt can't preempt this. */ + local_irq_save(flags); if (mce_available(__this_cpu_ptr(&cpu_info))) { machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_poll_banks)); @@ -1334,11 +1337,15 @@ static void mce_timer_fn(unsigned long data) iv = mce_adjust_timer(iv); } __this_cpu_write(mce_next_interval, iv); - /* Might have become 0 after CMCI storm subsided */ - if (iv) { + + /* Ensure the timer isn't already set and the interval has not become + * 0 after a CMCMI storm has subsided. + */ + if (!timer_pending(t) && iv) { t->expires = jiffies + iv; add_timer_on(t, smp_processor_id()); } + local_irq_restore(flags); } /* -- 2.0.0.526.g5318336