[PATCH v5 13/45] sched/rt: Use get/put_online_cpus_atomic() to prevent CPU offline

Srivatsa S. Bhat srivatsa.bhat at linux.vnet.ibm.com
Tue Jan 22 18:36:24 EST 2013

Once stop_machine() is gone from the CPU offline path, we won't be able to
depend on preempt_disable() or local_irq_disable() 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.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat at linux.vnet.ibm.com>

 kernel/sched/rt.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 418feb0..2a637be 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -6,6 +6,7 @@
 #include "sched.h"
 #include <linux/slab.h>
+#include <linux/cpu.h>
 static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
@@ -26,7 +27,9 @@ static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
 		if (!overrun)
+		get_online_cpus_atomic();
 		idle = do_sched_rt_period_timer(rt_b, overrun);
+		put_online_cpus_atomic();

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