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>

2 files changed, 13 insertions, 23 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 2f59cc334516..d17f6c4ddfa9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -953,14 +953,11 @@ void do_exit(long code)
         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 @@ void do_exit(long code)
         exit_shm(tsk);
         exit_files(tsk);
         exit_fs(tsk);
+        exit_task_work(tsk);
         check_stack_usage();
         exit_thread();
 
diff --git a/kernel/task_work.c b/kernel/task_work.c
index 76266fb665dc..fb396089f66a 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -5,34 +5,26 @@
 int
 task_work_add(struct task_struct *task, struct callback_head *twork, bool notify)
 {
+        struct callback_head *last, *first;
         unsigned long flags;
-        int err = -ESRCH;
 
-#ifndef TIF_NOTIFY_RESUME
-        if (notify)
-                return -ENOTSUPP;
-#endif
         /*
-         * We must not insert the new work if the task has already passed
-         * exit_task_work(). We rely on do_exit()->raw_spin_unlock_wait()
-         * and check PF_EXITING under pi_lock.
+         * Not inserting the new work if the task has already passed
+         * exit_task_work() is the responisbility of callers.
          */
         raw_spin_lock_irqsave(&task->pi_lock, flags);
-        if (likely(!(task->flags & PF_EXITING))) {
-                struct callback_head *last = task->task_works;
-                struct callback_head *first = last ? last->next : twork;
-                twork->next = first;
-                if (last)
-                        last->next = twork;
-                task->task_works = twork;
-                err = 0;
-        }
+        last = task->task_works;
+        first = last ? last->next : twork;
+        twork->next = first;
+        if (last)
+                last->next = twork;
+        task->task_works = twork;
         raw_spin_unlock_irqrestore(&task->pi_lock, flags);
 
         /* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */
-        if (likely(!err) && notify)
+        if (notify)
                 set_notify_resume(task);
-        return err;
+        return 0;
 }
 
 struct callback_head *