From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753113AbZHSQS7 (ORCPT ); Wed, 19 Aug 2009 12:18:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753087AbZHSQS6 (ORCPT ); Wed, 19 Aug 2009 12:18:58 -0400 Received: from hera.kernel.org ([140.211.167.34]:59359 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752911AbZHSQSz (ORCPT ); Wed, 19 Aug 2009 12:18:55 -0400 Date: Wed, 19 Aug 2009 16:18:34 GMT From: tip-bot for Suresh Siddha To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, venkatesh.pallipadi@intel.com, suresh.b.siddha@intel.com, tglx@linutronix.de, len.brown@intel.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, venkatesh.pallipadi@intel.com, suresh.b.siddha@intel.com, tglx@linutronix.de, len.brown@intel.com In-Reply-To: <1250544899.2709.210.camel@sbs-t61.sc.intel.com> References: <1250544899.2709.210.camel@sbs-t61.sc.intel.com> Subject: [tip:timers/urgent] clockevent: Prevent dead lock on clockevents_lock Message-ID: Git-Commit-ID: f833bab87fca5c3ce13778421b1365845843b976 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 19 Aug 2009 16:18:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: f833bab87fca5c3ce13778421b1365845843b976 Gitweb: http://git.kernel.org/tip/f833bab87fca5c3ce13778421b1365845843b976 Author: Suresh Siddha AuthorDate: Mon, 17 Aug 2009 14:34:59 -0700 Committer: Thomas Gleixner CommitDate: Wed, 19 Aug 2009 18:15:10 +0200 clockevent: Prevent dead lock on clockevents_lock Currently clockevents_notify() is called with interrupts enabled at some places and interrupts disabled at some other places. This results in a deadlock in this scenario. cpu A holds clockevents_lock in clockevents_notify() with irqs enabled cpu B waits for clockevents_lock in clockevents_notify() with irqs disabled cpu C doing set_mtrr() which will try to rendezvous of all the cpus. This will result in C and A come to the rendezvous point and waiting for B. B is stuck forever waiting for the spinlock and thus not reaching the rendezvous point. Fix the clockevents code so that clockevents_lock is taken with interrupts disabled and thus avoid the above deadlock. Also call lapic_timer_propagate_broadcast() on the destination cpu so that we avoid calling smp_call_function() in the clockevents notifier chain. This issue left us wondering if we need to change the MTRR rendezvous logic to use stop machine logic (instead of smp_call_function) or add a check in spinlock debug code to see if there are other spinlocks which gets taken under both interrupts enabled/disabled conditions. Signed-off-by: Suresh Siddha Signed-off-by: Venkatesh Pallipadi Cc: "Pallipadi Venkatesh" Cc: "Brown Len" LKML-Reference: <1250544899.2709.210.camel@sbs-t61.sc.intel.com> Signed-off-by: Thomas Gleixner --- arch/x86/kernel/process.c | 6 +----- drivers/acpi/processor_idle.c | 6 ++++-- kernel/time/clockevents.c | 16 ++++++++++------ kernel/time/tick-broadcast.c | 7 +++---- 4 files changed, 18 insertions(+), 17 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 994dd6a..071166a 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -519,16 +519,12 @@ static void c1e_idle(void) if (!cpumask_test_cpu(cpu, c1e_mask)) { cpumask_set_cpu(cpu, c1e_mask); /* - * Force broadcast so ACPI can not interfere. Needs - * to run with interrupts enabled as it uses - * smp_function_call. + * Force broadcast so ACPI can not interfere. */ - local_irq_enable(); clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE, &cpu); printk(KERN_INFO "Switch to broadcast mode on CPU%d\n", cpu); - local_irq_disable(); } clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 0efa59e..66393d5 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -162,8 +162,9 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr, pr->power.timer_broadcast_on_state = state; } -static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) +static void lapic_timer_propagate_broadcast(void *arg) { + struct acpi_processor *pr = (struct acpi_processor *) arg; unsigned long reason; reason = pr->power.timer_broadcast_on_state < INT_MAX ? @@ -635,7 +636,8 @@ static int acpi_processor_power_verify(struct acpi_processor *pr) working++; } - lapic_timer_propagate_broadcast(pr); + smp_call_function_single(pr->id, lapic_timer_propagate_broadcast, + pr, 1); return (working); } diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index a6dcd67..620b58a 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -137,11 +137,12 @@ int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, */ int clockevents_register_notifier(struct notifier_block *nb) { + unsigned long flags; int ret; - spin_lock(&clockevents_lock); + spin_lock_irqsave(&clockevents_lock, flags); ret = raw_notifier_chain_register(&clockevents_chain, nb); - spin_unlock(&clockevents_lock); + spin_unlock_irqrestore(&clockevents_lock, flags); return ret; } @@ -178,16 +179,18 @@ static void clockevents_notify_released(void) */ void clockevents_register_device(struct clock_event_device *dev) { + unsigned long flags; + BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); BUG_ON(!dev->cpumask); - spin_lock(&clockevents_lock); + spin_lock_irqsave(&clockevents_lock, flags); list_add(&dev->list, &clockevent_devices); clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); clockevents_notify_released(); - spin_unlock(&clockevents_lock); + spin_unlock_irqrestore(&clockevents_lock, flags); } EXPORT_SYMBOL_GPL(clockevents_register_device); @@ -235,8 +238,9 @@ void clockevents_exchange_device(struct clock_event_device *old, void clockevents_notify(unsigned long reason, void *arg) { struct list_head *node, *tmp; + unsigned long flags; - spin_lock(&clockevents_lock); + spin_lock_irqsave(&clockevents_lock, flags); clockevents_do_notify(reason, arg); switch (reason) { @@ -251,7 +255,7 @@ void clockevents_notify(unsigned long reason, void *arg) default: break; } - spin_unlock(&clockevents_lock); + spin_unlock_irqrestore(&clockevents_lock, flags); } EXPORT_SYMBOL_GPL(clockevents_notify); #endif diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 877dbed..c2ec250 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -205,11 +205,11 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev) * Powerstate information: The system enters/leaves a state, where * affected devices might stop */ -static void tick_do_broadcast_on_off(void *why) +static void tick_do_broadcast_on_off(unsigned long *reason) { struct clock_event_device *bc, *dev; struct tick_device *td; - unsigned long flags, *reason = why; + unsigned long flags; int cpu, bc_stopped; spin_lock_irqsave(&tick_broadcast_lock, flags); @@ -276,8 +276,7 @@ void tick_broadcast_on_off(unsigned long reason, int *oncpu) printk(KERN_ERR "tick-broadcast: ignoring broadcast for " "offline CPU #%d\n", *oncpu); else - smp_call_function_single(*oncpu, tick_do_broadcast_on_off, - &reason, 1); + tick_do_broadcast_on_off(&reason); } /*