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From: Richard Cochran <rcochran@linutronix.de>
To: <linux-kernel@vger.kernel.org>
Cc: <rt@linutronix.de>, John Stultz <john.stultz@linaro.org>,
	Jon Hunter <jonathanh@nvidia.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH] timers/core: Correct callback order during CPU hot plug.
Date: Wed, 27 Jul 2016 11:08:18 +0200
Message-ID: <1469610498-25914-1-git-send-email-rcochran@linutronix.de> (raw)
In-Reply-To: <20160713153337.566790058@linutronix.de>

On the tear-down path, the dead CPU callback for the timers was
misplaced within the 'cpuhp_state' enumeration.  There is a hidden
dependency between the timers and block multiqueue.  The timers
callback must happen before the block multiqueue callback otherwise a
RCU stall occurs.

This patch fixes the order within the hot plug state machine.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Fixes: 24f73b99716a ("timers/core: Convert to hotplug state machine")

Cc: John Stultz <john.stultz@linaro.org>
Cc: Jon Hunter <jonathanh@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
---
 include/linux/cpuhotplug.h |  2 +-
 kernel/cpu.c               | 15 ++++++++++-----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 6d405db..242bf53 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -20,9 +20,9 @@ enum cpuhp_state {
 	CPUHP_PROFILE_PREPARE,
 	CPUHP_X2APIC_PREPARE,
 	CPUHP_SMPCFD_PREPARE,
-	CPUHP_TIMERS_DEAD,
 	CPUHP_RCUTREE_PREP,
 	CPUHP_NOTIFY_PREPARE,
+	CPUHP_TIMERS_DEAD,
 	CPUHP_BRINGUP_CPU,
 	CPUHP_AP_IDLE_DEAD,
 	CPUHP_AP_OFFLINE,
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 67f4943..ec12b72 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1208,11 +1208,6 @@ static struct cpuhp_step cpuhp_bp_states[] = {
 		.startup = smpcfd_prepare_cpu,
 		.teardown = smpcfd_dead_cpu,
 	},
-	[CPUHP_TIMERS_DEAD] = {
-		.name = "timers dead",
-		.startup = NULL,
-		.teardown = timers_dead_cpu,
-	},
 	[CPUHP_RCUTREE_PREP] = {
 		.name = "RCU-tree prepare",
 		.startup = rcutree_prepare_cpu,
@@ -1229,6 +1224,16 @@ static struct cpuhp_step cpuhp_bp_states[] = {
 		.skip_onerr		= true,
 		.cant_stop		= true,
 	},
+	/*
+	 * On the tear-down path, timers_dead_cpu() must be invoked
+	 * before blk_mq_queue_reinit_notify() from notify_dead(),
+	 * otherwise a RCU stall occurs.
+	 */
+	[CPUHP_TIMERS_DEAD] = {
+		.name = "timers dead",
+		.startup = NULL,
+		.teardown = timers_dead_cpu,
+	},
 	/* Kicks the plugged cpu into life */
 	[CPUHP_BRINGUP_CPU] = {
 		.name			= "cpu:bringup",
-- 
2.1.4

  parent reply index

Thread overview: 170+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-13 17:16 [patch V2 00/67] cpuhotplug: Convert all priority notifiers to the state machine Anna-Maria Gleixner
2016-07-13 17:16 ` [patch V2 02/67] x86/vdso: Convert to hotplug " Anna-Maria Gleixner
2016-07-19  6:58   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 01/67] cpuhotplug: Handle early registration gracefully Anna-Maria Gleixner
2016-07-19  6:57   ` [tip:smp/hotplug] cpu/hotplug: " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 03/67] irqchip/gic: Convert to hotplug state machine Anna-Maria Gleixner
2016-07-19  6:58   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 04/67] irqchip/gicv3: " Anna-Maria Gleixner
2016-07-19  6:59   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 05/67] irqchip/hip04: " Anna-Maria Gleixner
2016-07-19  6:59   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 07/67] irqchip/bcm2836: " Anna-Maria Gleixner
2016-07-19  7:00   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 06/67] irqchip/armada-370-xp: " Anna-Maria Gleixner
2016-07-19  7:00   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 08/67] ARM: mvebu: " Anna-Maria Gleixner
2016-07-19  7:01   ` [tip:smp/hotplug] ARM/mvebu: " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 09/67] perf/core: " Anna-Maria Gleixner
2016-07-19  7:01   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 10/67] perf/x86: Convert the core to the " Anna-Maria Gleixner
2016-07-19  7:02   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 11/67] perf/x86/intel/uncore: Convert to " Anna-Maria Gleixner
2016-07-19  7:02   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 12/67] perf/x86/amd/uncore: " Anna-Maria Gleixner
2016-07-19  7:03   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 13/67] perf/x86/amd/ibs: " Anna-Maria Gleixner
2016-07-19  7:03   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 14/67] perf/x86/intel/rapl: " Anna-Maria Gleixner
2016-07-19  7:04   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 15/67] perf/x86/intel/cqm: Convert Intel CQM " Anna-Maria Gleixner
2016-07-19  7:04   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 16/67] perf/x86/intel/cstate: Convert Intel CSTATE " Anna-Maria Gleixner
2016-07-19  7:05   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 17/67] blackfin/perf: Convert hotplug notifier to " Anna-Maria Gleixner
2016-07-19  7:05   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 18/67] powerpc/perf: Convert book3s notifier to state machine callbacks Anna-Maria Gleixner
2016-07-19  7:06   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 19/67] s390/perf: Convert the hotplug notifier to state machine callbacks (Counter) Anna-Maria Gleixner
2016-07-19  7:07   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 20/67] s390/perf: Convert the hotplug notifier to state machine callbacks (Sampling) Anna-Maria Gleixner
2016-07-19  7:07   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 21/67] sh/perf: Convert the hotplug notifiers to state machine callbacks Anna-Maria Gleixner
2016-07-19  7:07   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 22/67] bus/arm-cci: Convert to hotplug statemachine Anna-Maria Gleixner
2016-07-15 12:38   ` Punit Agrawal
2016-07-19  7:08   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 23/67] bus/arm-ccn: " Anna-Maria Gleixner
2016-07-18 18:37   ` Pawel Moll
2016-07-19  7:09   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 24/67] xtensa/perf: Convert the hotplug notifier to state machine callbacks Anna-Maria Gleixner
2016-07-19  7:09   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 25/67] perf/x86/amd/power: Change hotplug notifier to a symmetric structure Anna-Maria Gleixner
2016-07-19  7:10   ` [tip:smp/hotplug] " tip-bot for Anna-Maria Gleixner
2016-07-13 17:16 ` [patch V2 26/67] perf/x86/amd/power: Convert the hotplug notifier to state machine Anna-Maria Gleixner
2016-07-19  7:11   ` [tip:smp/hotplug] " tip-bot for Anna-Maria Gleixner
2016-07-13 17:16 ` [patch V2 27/67] perf/core: Remove perf CPU notifier code Anna-Maria Gleixner
2016-07-19  7:11   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 28/67] workqueue: Convert to state machine callbacks Anna-Maria Gleixner
2016-07-19  7:12   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 29/67] x86/hpet: Convert to hotplug state machine Anna-Maria Gleixner
2016-07-19  7:13   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 30/67] powerpc/numa: " Anna-Maria Gleixner
2016-07-14 21:42   ` Anton Blanchard
2016-07-14 23:37     ` Anna-Maria Gleixner
2016-07-15  0:28       ` Anton Blanchard
2016-07-15  8:43         ` Ingo Molnar
2016-07-15 12:14           ` Anton Blanchard
2016-07-15 16:20         ` Sebastian Andrzej Siewior
2016-07-18 14:07           ` [PATCH v2] " Sebastian Andrzej Siewior
2016-07-22 19:57             ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 31/67] KVM/x86: Remove superfluous SMP function call Anna-Maria Gleixner
2016-07-14  8:21   ` Paolo Bonzini
2016-07-19  7:13   ` [tip:smp/hotplug] " tip-bot for Anna-Maria Gleixner
2016-07-13 17:16 ` [patch V2 32/67] x86/kvm/kvmclock: Convert to hotplug state machine Anna-Maria Gleixner
2016-07-19  7:14   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 33/67] x86/apb_timer: " Anna-Maria Gleixner
2016-07-19  7:14   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 34/67] arm: Convert VFP hotplug notifiers to " Anna-Maria Gleixner
2016-07-19  7:15   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 35/67] arm/perf: Convert to hotplug " Anna-Maria Gleixner
2016-07-15 13:08   ` Mark Rutland
2016-07-15 15:26     ` Sebastian Andrzej Siewior
2016-07-15 16:16       ` Mark Rutland
2016-07-19  7:16   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-19  7:35     ` Sebastian Andrzej Siewior
2016-07-19  7:48       ` Ingo Molnar
2016-07-19  9:02         ` [PATCH v2] " Sebastian Andrzej Siewior
2016-07-19  9:57           ` Mark Rutland
2016-07-19 11:17             ` [PATCH v3] " Sebastian Andrzej Siewior
2016-07-20  8:01               ` Ingo Molnar
2016-07-20 10:41               ` [tip:smp/hotplug] arm/perf: Fix hotplug state machine conversion tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 36/67] virt: Convert kvm hotplug to state machine Anna-Maria Gleixner
2016-07-19  7:16   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 37/67] ACPI/processor: Avoid STARTING/DYING actions in a more logical way Anna-Maria Gleixner
2016-07-19  7:17   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 38/67] clocksource/arm_arch_timer: Convert to hotplug state machine Anna-Maria Gleixner
2016-07-19  7:17   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 39/67] clocksource/dummy_timer: " Anna-Maria Gleixner
2016-07-19  7:18   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 40/67] clocksource/metag: " Anna-Maria Gleixner
2016-07-19  7:19   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 41/67] clocksource/qcom-timer: " Anna-Maria Gleixner
2016-07-19  7:19   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 42/67] clocksource/mips-gic: " Anna-Maria Gleixner
2016-07-19  7:20   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 43/67] leds/trigger/cpu: " Anna-Maria Gleixner
2016-07-14  7:19   ` Jacek Anaszewski
2016-07-14  7:47     ` Ingo Molnar
2016-07-14  8:10       ` Jacek Anaszewski
2016-07-14  9:41         ` Peter Zijlstra
2016-07-14 11:23           ` Jacek Anaszewski
2016-07-14 11:33             ` Thomas Gleixner
2016-07-14 11:55               ` Jacek Anaszewski
2016-07-15 14:10                 ` Sebastian Andrzej Siewior
2016-07-18  8:26                   ` Jacek Anaszewski
2016-07-19  7:20   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 44/67] arm/kvm/vgic: " Anna-Maria Gleixner
2016-07-19  7:21   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 45/67] arm/kvm/arch_timer: " Anna-Maria Gleixner
2016-07-19  7:21   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 46/67] metag/perf: " Anna-Maria Gleixner
2016-07-19  7:22   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 47/67] arm/l2c: " Anna-Maria Gleixner
2016-07-19  7:22   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 48/67] arm/twd: " Anna-Maria Gleixner
2016-07-19  7:23   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 49/67] arm/xen: " Anna-Maria Gleixner
2016-07-13 18:21   ` Stefano Stabellini
2016-07-19  7:23   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 50/67] MIPS/Loongson-3: Convert oprofile " Anna-Maria Gleixner
2016-07-19  7:24   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 51/67] hwtracing/coresight-etm3x: Convert " Anna-Maria Gleixner
2016-07-19  7:24   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 52/67] hwtracing/coresight-etm4x: " Anna-Maria Gleixner
2016-07-19  7:25   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 53/67] arm64/armv8 deprecated: " Anna-Maria Gleixner
2016-07-19  7:25   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 54/67] x86/tboot: " Anna-Maria Gleixner
2016-07-19  7:26   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:16 ` [patch V2 55/67] hrtimer: " Anna-Maria Gleixner
2016-07-19  7:26   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:16 ` [patch V2 57/67] profile: " Anna-Maria Gleixner
2016-07-19  7:27   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:16 ` [patch V2 56/67] timers/core: " Anna-Maria Gleixner
2016-07-19  7:27   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-27  9:08   ` Richard Cochran [this message]
2016-07-27  9:50     ` [PATCH] timers/core: Correct callback order during CPU hot plug Jon Hunter
2016-07-28 15:34     ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-28 16:57     ` tip-bot for Richard Cochran
2016-07-13 17:17 ` [patch V2 58/67] x86/x2apic: Convert to CPU hotplug state machine Anna-Maria Gleixner
2016-07-19  7:28   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2016-07-13 17:17 ` [patch V2 59/67] smp: Convert core to " Anna-Maria Gleixner
2016-07-19  7:28   ` [tip:smp/hotplug] smp/cfd: " tip-bot for Richard Weinberger
2016-07-13 17:17 ` [patch V2 60/67] KVM/arm/arm64/vgic-new: Convert " Anna-Maria Gleixner
2016-07-14 13:08   ` Marc Zyngier
2016-07-19  7:29   ` [tip:smp/hotplug] " tip-bot for Anna-Maria Gleixner
2016-07-13 17:17 ` [patch V2 61/67] rcu: Convert rcutree " Anna-Maria Gleixner
2016-07-19  7:29   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-07-13 17:17 ` [patch V2 62/67] [PATCH] clocksource: arm_global_timer: Convert " Anna-Maria Gleixner
2016-07-19  7:30   ` [tip:smp/hotplug] clocksource/arm_global_timer: " tip-bot for Richard Cochran
2016-07-13 17:17 ` [patch V2 63/67] clocksource/exynos_mct: " Anna-Maria Gleixner
2016-07-19  7:31   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:17 ` [patch V2 64/67] clocksource/armada-370-xp: " Anna-Maria Gleixner
2016-07-19  7:31   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:17 ` [patch V2 65/67] clocksource/atlas7: " Anna-Maria Gleixner
2016-07-19  7:32   ` [tip:smp/hotplug] " tip-bot for Richard Cochran
2016-07-13 17:17 ` [patch V2 66/67] ARC/time: " Anna-Maria Gleixner
2016-07-19  7:32   ` [tip:smp/hotplug] " tip-bot for Anna-Maria Gleixner
2016-07-13 17:17 ` [patch V2 67/67] cpuhotplug: Remove CPU_STARTING and CPU_DYING notifier Anna-Maria Gleixner
2016-07-13 19:32 ` [patch V2 00/67] cpuhotplug: Convert all priority notifiers to the state machine Jason Cooper

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