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Commit 86773473 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
parent 9843a1e9

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -2160,7 +2160,7 @@ extern int kill_pid_info_as_uid(int, struct siginfo *, struct pid *, uid_t, uid_ 
extern int kill_pgrp(struct pid *pid, int sig, int priv);

extern int kill_pid(struct pid *pid, int sig, int priv);

extern int kill_proc_info(int, struct siginfo *, pid_t);

extern bool do_notify_parent(struct task_struct *, int);

extern __must_check bool do_notify_parent(struct task_struct *, int);

extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);

extern void force_sig(int, struct task_struct *);

extern int send_sig(int, struct task_struct *, int);

kernel/exit.c

+8 −21
Original line number Diff line number Diff line
@@ -190,21 +190,12 @@ void release_task(struct task_struct * p) 
	leader = p->group_leader;

	if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {

		BUG_ON(task_detached(leader));

		do_notify_parent(leader, leader->exit_signal);

		/*

		 * If we were the last child thread and the leader has

		 * exited already, and the leader's parent ignores SIGCHLD,

		 * then we are the one who should release the leader.

		 *

		 * do_notify_parent() will have marked it self-reaping in

		 * that case.

		 */

		zap_leader = task_detached(leader);



		/*

		 * This maintains the invariant that release_task()

		 * only runs on a task in EXIT_DEAD, just for sanity.

		 */

		zap_leader = do_notify_parent(leader, leader->exit_signal);

		if (zap_leader)

			leader->exit_state = EXIT_DEAD;

	}
@@ -766,8 +757,7 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p, 
	/* If it has exited notify the new parent about this child's death. */

	if (!p->ptrace &&

	    p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {

		do_notify_parent(p, p->exit_signal);

		if (task_detached(p)) {

		if (do_notify_parent(p, p->exit_signal)) {

			p->exit_state = EXIT_DEAD;

			list_move_tail(&p->sibling, dead);

		}
@@ -1351,17 +1341,14 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 
		/* We dropped tasklist, ptracer could die and untrace */

		ptrace_unlink(p);

		/*

		 * If this is not a detached task, notify the parent.

		 * If it's still not detached after that, don't release

		 * it now.

		 * If this is not a sub-thread, notify the parent.

		 * If parent wants a zombie, don't release it now.

		 */

		if (!task_detached(p)) {

			do_notify_parent(p, p->exit_signal);

			if (!task_detached(p)) {

		if (thread_group_leader(p) &&

		    !do_notify_parent(p, p->exit_signal)) {

			p->exit_state = EXIT_ZOMBIE;

			p = NULL;

		}

		}

		write_unlock_irq(&tasklist_lock);

	}

	if (p != NULL)