diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2017-12-27 21:37:25 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-02 20:35:17 +0100 |
| commit | 249d4a9b3246f4ec92433ba8ea3bae5ceb4dc1ed (patch) | |
| tree | 471060a6d4f5a04e15c873ba95aa1e48bcb4be95 /kernel | |
| parent | 574e543ff970ea208d6d97524e0373d3741a6a34 (diff) | |
timers: Reinitialize per cpu bases on hotplug
commit 26456f87aca7157c057de65c9414b37f1ab881d1 upstream.
The timer wheel bases are not (re)initialized on CPU hotplug. That leaves
them with a potentially stale clk and next_expiry valuem, which can cause
trouble then the CPU is plugged.
Add a prepare callback which forwards the clock, sets next_expiry to far in
the future and reset the control flags to a known state.
Set base->must_forward_clk so the first timer which is queued will try to
forward the clock to current jiffies.
Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel")
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1712272152200.2431@nanos
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpu.c | 4 | ||||
| -rw-r--r-- | kernel/time/timer.c | 15 |
2 files changed, 17 insertions, 2 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index e1436ca4aed0..802eb3361a0a 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1309,9 +1309,9 @@ static struct cpuhp_step cpuhp_bp_states[] = { * before blk_mq_queue_reinit_notify() from notify_dead(), * otherwise a RCU stall occurs. */ - [CPUHP_TIMERS_DEAD] = { + [CPUHP_TIMERS_PREPARE] = { .name = "timers:dead", - .startup.single = NULL, + .startup.single = timers_prepare_cpu, .teardown.single = timers_dead_cpu, }, /* Kicks the plugged cpu into life */ diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 26c2f659a40f..e872f7f05e8a 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1851,6 +1851,21 @@ static void migrate_timer_list(struct timer_base *new_base, struct hlist_head *h } } +int timers_prepare_cpu(unsigned int cpu) +{ + struct timer_base *base; + int b; + + for (b = 0; b < NR_BASES; b++) { + base = per_cpu_ptr(&timer_bases[b], cpu); + base->clk = jiffies; + base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA; + base->is_idle = false; + base->must_forward_clk = true; + } + return 0; +} + int timers_dead_cpu(unsigned int cpu) { struct timer_base *old_base; |