From 62bcf9d992ecc19ea4f37ff57ee0b3333e3e843e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 23 Mar 2011 10:37:01 +0100 Subject: [PATCH] job control: Job control stop notifications should always go to the real parent The stopped notifications in do_signal_stop() and exit_signals() are always for the completion of job control. The one in do_signal_stop() may be delivered to the ptracer if PTRACE_ATTACH races with notification and the one in exit_signals() if task exits while ptraced. In both cases, the notifications are meaningless and confusing to the ptracer as it never accesses the group stop state while the real parent would miss notifications for the events it is watching. Make sure these notifications always go to the real parent by calling do_notify_parent_cld_stop() with %false @for_ptrace. Signed-off-by: Tejun Heo Acked-by: Oleg Nesterov --- kernel/signal.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 69d60540a680..9f10b246fd46 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1898,10 +1898,18 @@ retry: __set_current_state(TASK_STOPPED); spin_unlock_irq(¤t->sighand->siglock); + /* + * Notify the parent of the group stop completion. Because + * we're not holding either the siglock or tasklist_lock + * here, ptracer may attach inbetween; however, this is for + * group stop and should always be delivered to the real + * parent of the group leader. The new ptracer will get + * its notification when this task transitions into + * TASK_TRACED. + */ if (notify) { read_lock(&tasklist_lock); - do_notify_parent_cldstop(current, task_ptrace(current), - notify); + do_notify_parent_cldstop(current, false, notify); read_unlock(&tasklist_lock); } @@ -2182,9 +2190,13 @@ void exit_signals(struct task_struct *tsk) out: spin_unlock_irq(&tsk->sighand->siglock); + /* + * If group stop has completed, deliver the notification. This + * should always go to the real parent of the group leader. + */ if (unlikely(group_stop)) { read_lock(&tasklist_lock); - do_notify_parent_cldstop(tsk, task_ptrace(tsk), group_stop); + do_notify_parent_cldstop(tsk, false, group_stop); read_unlock(&tasklist_lock); } } -- 2.34.1