signals: de_thread: simplify the ->child_reaper switching

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>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-04-30 00:53:04 -07:00 committed by Linus Torvalds
parent fae5fa44f1
commit 7a5e873f09

View File

@ -766,9 +766,7 @@ static int de_thread(struct task_struct *tsk)
/*
* 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)) {
/*
@ -776,21 +774,10 @@ static int de_thread(struct task_struct *tsk)
* 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;
@ -821,6 +808,8 @@ static int de_thread(struct task_struct *tsk)
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.