[PATCH v2 16/45] tick-broadcast: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-06-25 20:31:41
Also in:
linux-arch, linux-pm, lkml, netdev
Subsystem:
nohz, dynticks support, the rest · Maintainers:
Anna-Maria Behnsen, Frederic Weisbecker, Ingo Molnar, Thomas Gleixner, Linus Torvalds
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 <redacted> Signed-off-by: Srivatsa S. Bhat <redacted> --- 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(); }