make do_notify_parent() __must_check, update the callers
Change other callers of do_notify_parent() to check the value it returns, this makes the subsequent task_detached() unnecessary. Mark do_notify_parent() as __must_check. Use thread_group_leader() instead of !task_detached() to check if we need to notify the real parent in wait_task_zombie(). Remove the stale comment in release_task(). "just for sanity" is no longer true, we have to set EXIT_DEAD to avoid the races with do_wait(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Tejun Heo <tj@kernel.org>
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9843a1e977
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@ -2160,7 +2160,7 @@ extern int kill_pid_info_as_uid(int, struct siginfo *, struct pid *, uid_t, uid_
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extern int kill_pgrp(struct pid *pid, int sig, int priv);
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extern int kill_pid(struct pid *pid, int sig, int priv);
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extern int kill_proc_info(int, struct siginfo *, pid_t);
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extern bool do_notify_parent(struct task_struct *, int);
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extern __must_check bool do_notify_parent(struct task_struct *, int);
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extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
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extern void force_sig(int, struct task_struct *);
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extern int send_sig(int, struct task_struct *, int);
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@ -190,21 +190,12 @@ repeat:
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leader = p->group_leader;
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if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
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BUG_ON(task_detached(leader));
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do_notify_parent(leader, leader->exit_signal);
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/*
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* If we were the last child thread and the leader has
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* exited already, and the leader's parent ignores SIGCHLD,
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* then we are the one who should release the leader.
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*
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* do_notify_parent() will have marked it self-reaping in
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* that case.
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*/
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zap_leader = task_detached(leader);
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/*
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* This maintains the invariant that release_task()
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* only runs on a task in EXIT_DEAD, just for sanity.
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*/
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zap_leader = do_notify_parent(leader, leader->exit_signal);
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if (zap_leader)
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leader->exit_state = EXIT_DEAD;
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}
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@ -766,8 +757,7 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
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/* If it has exited notify the new parent about this child's death. */
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if (!p->ptrace &&
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p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
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do_notify_parent(p, p->exit_signal);
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if (task_detached(p)) {
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if (do_notify_parent(p, p->exit_signal)) {
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p->exit_state = EXIT_DEAD;
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list_move_tail(&p->sibling, dead);
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}
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@ -1351,16 +1341,13 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
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/* We dropped tasklist, ptracer could die and untrace */
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ptrace_unlink(p);
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/*
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* If this is not a detached task, notify the parent.
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* If it's still not detached after that, don't release
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* it now.
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* If this is not a sub-thread, notify the parent.
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* If parent wants a zombie, don't release it now.
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*/
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if (!task_detached(p)) {
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do_notify_parent(p, p->exit_signal);
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if (!task_detached(p)) {
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p->exit_state = EXIT_ZOMBIE;
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p = NULL;
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}
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if (thread_group_leader(p) &&
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!do_notify_parent(p, p->exit_signal)) {
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p->exit_state = EXIT_ZOMBIE;
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p = NULL;
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}
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write_unlock_irq(&tasklist_lock);
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}
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