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/time/tick-broadcast.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 9d96a54..1e4ac45 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -227,12 +227,14 @@ static void tick_do_broadcast(struct cpumask *mask)
*/
static void tick_do_periodic_broadcast(void)
{
+ get_online_cpus_atomic();
raw_spin_lock(&tick_broadcast_lock);
cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
tick_do_broadcast(tmpmask);
raw_spin_unlock(&tick_broadcast_lock);
+ put_online_cpus_atomic();
}
/*
@@ -335,11 +337,13 @@ out:
*/
void tick_broadcast_on_off(unsigned long reason, int *oncpu)
{
+ get_online_cpus_atomic();
if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
"offline CPU #%d\n", *oncpu);
else
tick_do_broadcast_on_off(&reason);
+ put_online_cpus_atomic();
}
/*
@@ -505,6 +509,7 @@ static void tick_handle_oneshot_broadcast(struct
clock_event_device *dev)
ktime_t now, next_event;
int cpu, next_cpu = 0;
+ get_online_cpus_atomic();
raw_spin_lock(&tick_broadcast_lock);
again:
dev->next_event.tv64 = KTIME_MAX;
@@ -562,6 +567,7 @@ again:
goto again;
}
raw_spin_unlock(&tick_broadcast_lock);
+ put_online_cpus_atomic();
}
/*
@@ -756,6 +762,7 @@ void tick_broadcast_switch_to_oneshot(void)
struct clock_event_device *bc;
unsigned long flags;
+ get_online_cpus_atomic();
raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
@@ -764,6 +771,7 @@ void tick_broadcast_switch_to_oneshot(void)
tick_broadcast_setup_oneshot(bc);
raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+ put_online_cpus_atomic();
}
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