Now that we rely on SIGNAL_UNKILLABLE flag, de_thread() doesn't need the nasty
hack to kill the old ->child_reaper during the mt-exec.
This also means we can avoid taking tasklist_lock around zap_other_threads().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 25/fs/exec.c~2_EXEC_KILL_HACK 2008-03-03 17:01:36.000000000 +0300
+++ 25/fs/exec.c 2008-03-16 15:20:25.000000000 +0300
@@ -757,9 +757,7 @@ static int de_thread(struct task_struct
/*
* Kill all other threads in the thread group.
- * We must hold tasklist_lock to call zap_other_threads.
*/
- read_lock(&tasklist_lock);
spin_lock_irq(lock);
if (signal_group_exit(sig)) {
/*
@@ -767,21 +765,10 @@ static int de_thread(struct task_struct
* return so that the signal is processed.
*/
spin_unlock_irq(lock);
- read_unlock(&tasklist_lock);
return -EAGAIN;
}
-
- /*
- * child_reaper ignores SIGKILL, change it now.
- * Reparenting needs write_lock on tasklist_lock,
- * so it is safe to do it under read_lock.
- */
- if (unlikely(tsk->group_leader == task_child_reaper(tsk)))
- task_active_pid_ns(tsk)->child_reaper = tsk;
-
sig->group_exit_task = tsk;
zap_other_threads(tsk);
- read_unlock(&tasklist_lock);
/* Account for the thread group leader hanging around: */
count = thread_group_leader(tsk) ? 1 : 2;
@@ -812,6 +799,8 @@ static int de_thread(struct task_struct
schedule();
}
+ if (unlikely(task_child_reaper(tsk) == leader))
+ task_active_pid_ns(tsk)->child_reaper = tsk;
/*
* The only record we have of the real-time age of a
* process, regardless of execs it's done, is start_time.
--
