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.

Cc: "James E.J. Bottomley" <redacted>
Cc: linux-parisc at vger.kernel.org
Signed-off-by: Srivatsa S. Bhat <redacted>
---

 arch/parisc/kernel/smp.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 6266730..f7851b7 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c

@@ -229,11 +229,13 @@ static inline void
 send_IPI_allbutself(enum ipi_message_type op)
 {
 	int i;
-	
+
+	get_online_cpus_atomic();
 	for_each_online_cpu(i) {
 		if (i != smp_processor_id())
 			send_IPI_single(i, op);
 	}
+	put_online_cpus_atomic();
 }