[v3,19/45] softirq: Use get/put_online_cpus_atomic() to prevent CPU offline

Message ID 20130627195601.29830.15576.stgit@srivatsabhat.in.ibm.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Srivatsa S. Bhat June 27, 2013, 7:56 p.m.
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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>

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

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diff --git a/kernel/softirq.c b/kernel/softirq.c
index 3d6833f..c289722 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -644,14 +644,17 @@  static void remote_softirq_receive(void *data)
 static int __try_remote_softirq(struct call_single_data *cp, int cpu, int softirq)
+	get_online_cpus_atomic();
 	if (cpu_online(cpu)) {
 		cp->func = remote_softirq_receive;
 		cp->info = &softirq;
 		cp->flags = 0;
 		__smp_call_function_single(cpu, cp, 0);
+		put_online_cpus_atomic();
 		return 0;
+	put_online_cpus_atomic();
 	return 1;