Messages in this thread Patch in this message | | | From | "Srivatsa S. Bhat" <> | Subject | [RFC PATCH v4 7/9] yield_to(), cpu-hotplug: Prevent offlining of other CPUs properly | Date | Tue, 11 Dec 2012 19:35:18 +0530 |
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Once stop_machine() is gone from the CPU offline path, we won't be able to depend on local_irq_save() 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@linux.vnet.ibm.com> ---
kernel/sched/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cff7656..4b982bf 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4312,6 +4312,7 @@ bool __sched yield_to(struct task_struct *p, bool preempt) unsigned long flags; bool yielded = 0; + get_online_cpus_atomic(); local_irq_save(flags); rq = this_rq(); @@ -4339,13 +4340,14 @@ again: * Make p's CPU reschedule; pick_next_entity takes care of * fairness. */ - if (preempt && rq != p_rq) + if (preempt && rq != p_rq && cpu_online(task_cpu(p))) resched_task(p_rq->curr); } out: double_rq_unlock(rq, p_rq); local_irq_restore(flags); + put_online_cpus_atomic(); if (yielded) schedule();
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