[PATCH v6 14/46] sched/rt: Use get/put_online_cpus_atomic() toprevent CPU offline

From: Srivatsa S. Bhat
Date: Mon Feb 18 2013 - 07:42:33 EST


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@xxxxxxxxxxxxxxxxxx>
---

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

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4f02b28..e546c98 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)
break;

+ get_online_cpus_atomic();
idle = do_sched_rt_period_timer(rt_b, overrun);
+ put_online_cpus_atomic();
}

return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;

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