[PATCH] APM does unsafe conditional set_cpus_allowed

From: Zwane Mwaikambo <zwane@linuxpower.ca>

kapmd does a conditional check in order to decide whether to set the task's
cpu affinity mask.  This can change during runtime, therefore we
unconditionally set it.  There is an early exit in set_cpus_allowed if the
current processor is in the allowed mask anyway.

arch/i386/kernel/apm.c

@@ -512,9 +512,8 @@ static unsigned long apm_save_cpus(void)
 {
 	unsigned long x = current->cpus_allowed;
 	/* Some bioses don't like being called from CPU != 0 */
-	set_cpus_allowed(current, 1 << 0);
-	if (unlikely(smp_processor_id() != 0))
-		BUG();
+	set_cpus_allowed(current, 1UL << 0);
+	BUG_ON(smp_processor_id() != 0);
 	return x;
 }
 
@@ -914,11 +913,8 @@ static void apm_power_off(void)
 	 */
 #ifdef CONFIG_SMP
 	/* Some bioses don't like being called from CPU != 0 */
-	if (smp_processor_id() != 0) {
-		set_cpus_allowed(current, 1 << 0);
-		if (unlikely(smp_processor_id() != 0))
-			BUG();
-	}
+	set_cpus_allowed(current, 1UL << 0);
+	BUG_ON(smp_processor_id() != 0);
 #endif
 	if (apm_info.realmode_power_off)
 	{
@@ -1708,11 +1704,8 @@ static int apm(void *unused)
 	 * Some bioses don't like being called from CPU != 0.
 	 * Method suggested by Ingo Molnar.
 	 */
-	if (smp_processor_id() != 0) {
-		set_cpus_allowed(current, 1 << 0);
-		if (unlikely(smp_processor_id() != 0))
-			BUG();
-	}
+	set_cpus_allowed(current, 1UL << 0);
+	BUG_ON(smp_processor_id() != 0);
 #endif
 
 	if (apm_info.connection_version == 0) {