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| author | Richard Cochran <rcochran@linutronix.de> | 2016-07-27 11:08:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-07-28 18:56:22 +0200 |
| commit | 4fae16dffb812f0e0d98a0b2b0856ca48ca63e6c (patch) | |
| tree | c661ae0eaa75eb0f4af66870bb0c34a5b1c4c273 | |
| parent | leds/trigger/cpu: Move from CPU_STARTING to ONLINE level (diff) | |
| download | linux-4fae16dffb812f0e0d98a0b2b0856ca48ca63e6c.tar.xz linux-4fae16dffb812f0e0d98a0b2b0856ca48ca63e6c.zip | |
timers/core: Correct callback order during CPU hot plug
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.
Move the timers callback to the proper place in the state machine.
Reported-and-tested-by: Jon Hunter <jonathanh@nvidia.com>
Reported-by: kbuild test robot <lkp@intel.com>
Fixes: 24f73b99716a ("timers/core: Convert to hotplug state machine")
Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: John Stultz <john.stultz@linaro.org>
Cc: rt@linutronix.de
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1469610498-25914-1-git-send-email-rcochran@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | include/linux/cpuhotplug.h | 2 | ||||
| -rw-r--r-- | kernel/cpu.c | 15 |
2 files changed, 11 insertions, 6 deletions
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 6d405db6fb12..242bf530edfc 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 f24f45915b54..341bf80f80bd 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1200,11 +1200,6 @@ 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, @@ -1221,6 +1216,16 @@ 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", |