[PATCH] x86_64: Fix cluster mode send_IPI_allbutself to use get_cpu()/put_cpu()

Need to ensure we dont get prempted when we clear ourself from mask when using
clustered mode genapic code.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/genapic_cluster.c

@@ -72,10 +72,14 @@ static void cluster_send_IPI_mask(cpumask_t mask, int vector)
 static void cluster_send_IPI_allbutself(int vector)
 {
 	cpumask_t mask = cpu_online_map;
-	cpu_clear(smp_processor_id(), mask);
+	int me = get_cpu(); /* Ensure we are not preempted when we clear */
+
+	cpu_clear(me, mask);
 
 	if (!cpus_empty(mask))
 		cluster_send_IPI_mask(mask, vector);
+
+	put_cpu();
 }
 
 static void cluster_send_IPI_all(int vector)