cpuset: modify cpuset_set_cpus_allowed to use cpumask pointer

* Modify cpuset_cpus_allowed to return the currently allowed cpuset
    via a pointer argument instead of as the function return value.

  * Use new set_cpus_allowed_ptr function.

  * Cleanup CPU_MASK_ALL and NODE_MASK_ALL uses.

Depends on:
	[sched-devel]: sched: add new set_cpus_allowed_ptr function

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

mm/pdflush.c

@@ -187,8 +187,8 @@ static int pdflush(void *dummy)
 	 * This is needed as pdflush's are dynamically created and destroyed.
 	 * The boottime pdflush's are easily placed w/o these 2 lines.
 	 */
-	cpus_allowed = cpuset_cpus_allowed(current);
-	set_cpus_allowed(current, cpus_allowed);
+	cpuset_cpus_allowed(current, &cpus_allowed);
+	set_cpus_allowed_ptr(current, &cpus_allowed);
 
 	return __pdflush(&my_work);
 }