cpuset: two minor code-cleanups

In cpuset_update_task_memory_state() local variable struct task_struct
*tsk = current;

And local variable tsk is used 14 times and statement task_cs(tsk) is used
twice in this function.  So using task_cs(tsk) instead of task_cs(current)
is better for readability.

And "(struct cgroup_scanner *)&scan" is not good for readability also.
(and "container_of" is used in cpuset_do_move_task(), not
"(cpuset_hotplug_scanner *)scan")

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/cpuset.c

@@ -365,7 +365,7 @@ void cpuset_update_task_memory_state(void)
 		my_cpusets_mem_gen = top_cpuset.mems_generation;
 	} else {
 		rcu_read_lock();
-		my_cpusets_mem_gen = task_cs(current)->mems_generation;
+		my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
 		rcu_read_unlock();
 	}
 
@@ -1777,7 +1777,7 @@ static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
 	scan.scan.heap = NULL;
 	scan.to = to->css.cgroup;
 
-	if (cgroup_scan_tasks((struct cgroup_scanner *)&scan))
+	if (cgroup_scan_tasks(&scan.scan))
 		printk(KERN_ERR "move_member_tasks_to_cpuset: "
 				"cgroup_scan_tasks failed\n");
 }