Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.
Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going
offline, while invoking from atomic context.
Cc: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com>
---
kernel/timer.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/timer.c b/kernel/timer.c
index 15ffdb3..5db594c 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -729,6 +729,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
timer_stats_timer_set_start_info(timer);
BUG_ON(!timer->function);
+ get_online_cpus_atomic();
base = lock_timer_base(timer, &flags);
ret = detach_if_pending(timer, base, false);
@@ -768,6 +769,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
out_unlock:
spin_unlock_irqrestore(&base->lock, flags);
+ put_online_cpus_atomic();
return ret;
}
@@ -926,6 +928,7 @@ void add_timer_on(struct timer_list *timer, int cpu)
timer_stats_timer_set_start_info(timer);
BUG_ON(timer_pending(timer) || !timer->function);
+ get_online_cpus_atomic();
spin_lock_irqsave(&base->lock, flags);
timer_set_base(timer, base);
debug_activate(timer, timer->expires);
@@ -940,6 +943,7 @@ void add_timer_on(struct timer_list *timer, int cpu)
*/
wake_up_nohz_cpu(cpu);
spin_unlock_irqrestore(&base->lock, flags);
+ put_online_cpus_atomic();
}
EXPORT_SYMBOL_GPL(add_timer_on);
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