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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>
This commit is contained in:
Oleg Nesterov 2011-06-22 23:09:09 +02:00
parent 9843a1e977
commit 8677347378
2 changed files with 9 additions and 22 deletions
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2
include/linux/sched.h
View File

@ -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);

29
kernel/exit.c
View File

@ -190,21 +190,12 @@ repeat:
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);
}
@ -1351,16 +1341,13 @@ 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)) {
p->exit_state = EXIT_ZOMBIE;
p = NULL;
}
if (thread_group_leader(p) &&
!do_notify_parent(p, p->exit_signal)) {
p->exit_state = EXIT_ZOMBIE;
p = NULL;
}
write_unlock_irq(&tasklist_lock);
}