Messages in this thread | | | From | (Eric W. Biederman) | Date | Wed, 28 Nov 2018 09:23:39 -0600 | Subject | Re: [PATCH] prctl: add PR_{GET,SET}_KILL_DESCENDANTS_ON_EXIT |
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Oleg Nesterov <oleg@redhat.com> writes:
> On 11/27, Jürg Billeter wrote: >> >> @@ -704,6 +713,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead) >> struct task_struct *p, *n; >> LIST_HEAD(dead); >> >> + if (group_dead && tsk->signal->kill_descendants_on_exit) >> + walk_process_tree(tsk, kill_descendant_visitor, NULL); > > Well, this is not exactly right, at least this is suboptimal in that > other sub-threads can too call walk_process_tree(kill_descendant_visitor) > later for no reason.
Oleg I think I am missing something.
Reading kernel/exit.c I see "group_dead = atomic_dec_and_test(&tsk->signal->live)". Which seems like enough to ensure exactly one task/thread calls walk_process_tree.
Can you explain what I am missing?
Eric
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