move exit_task_work() past exit_files() et.al.

... and get rid of PF_EXITING check in task_work_add().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/exit.c b/kernel/exit.c
index 2f59cc3..d17f6c4 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -953,14 +953,11 @@
 	exit_signals(tsk);  /* sets PF_EXITING */
 	/*
 	 * tsk->flags are checked in the futex code to protect against
-	 * an exiting task cleaning up the robust pi futexes, and in
-	 * task_work_add() to avoid the race with exit_task_work().
+	 * an exiting task cleaning up the robust pi futexes.
 	 */
 	smp_mb();
 	raw_spin_unlock_wait(&tsk->pi_lock);
 
-	exit_task_work(tsk);
-
 	if (unlikely(in_atomic()))
 		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 				current->comm, task_pid_nr(current),
@@ -995,6 +992,7 @@
 	exit_shm(tsk);
 	exit_files(tsk);
 	exit_fs(tsk);
+	exit_task_work(tsk);
 	check_stack_usage();
 	exit_thread();