Fix tsk->exit_state usage

tsk->exit_state can only be 0, EXIT_ZOMBIE, or EXIT_DEAD.  A non-zero test
is the same as tsk->exit_state & (EXIT_ZOMBIE | EXIT_DEAD), so just testing
tsk->exit_state is sufficient.

Signed-off-by: Eugene Teo <eugeneteo@kernel.sg>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/array.c

@@ -146,8 +146,7 @@ static inline const char *get_task_state(struct task_struct *tsk)
 					    TASK_UNINTERRUPTIBLE |
 					    TASK_STOPPED |
 					    TASK_TRACED)) |
-			(tsk->exit_state & (EXIT_ZOMBIE |
-					    EXIT_DEAD));
+					   tsk->exit_state;
 	const char **p = &task_state_array[0];
 
 	while (state) {

kernel/fork.c

@@ -117,7 +117,7 @@ EXPORT_SYMBOL(free_task);
 
 void __put_task_struct(struct task_struct *tsk)
 {
-	WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
+	WARN_ON(!tsk->exit_state);
 	WARN_ON(atomic_read(&tsk->usage));
 	WARN_ON(tsk == current);
 

kernel/sched.c

@@ -5279,7 +5279,7 @@ static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
 	struct rq *rq = cpu_rq(dead_cpu);
 
 	/* Must be exiting, otherwise would be on tasklist. */
-	BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
+	BUG_ON(!p->exit_state);
 
 	/* Cannot have done final schedule yet: would have vanished. */
 	BUG_ON(p->state == TASK_DEAD);