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-rw-r--r--include/linux/sched.h1
-rw-r--r--kernel/exit.c50
2 files changed, 22 insertions, 29 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f8497059f88c..7781de5e5e7b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -212,6 +212,7 @@ print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq);
/* in tsk->exit_state */
#define EXIT_ZOMBIE 16
#define EXIT_DEAD 32
+#define EXIT_TRACE (EXIT_ZOMBIE | EXIT_DEAD)
/* in tsk->state again */
#define TASK_DEAD 64
#define TASK_WAKEKILL 128
diff --git a/kernel/exit.c b/kernel/exit.c
index e354cbb13a9b..022a0ff17318 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -560,6 +560,9 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
struct list_head *dead)
{
list_move_tail(&p->sibling, &p->real_parent->children);
+
+ if (p->exit_state == EXIT_DEAD)
+ return;
/*
* If this is a threaded reparent there is no need to
* notify anyone anything has happened.
@@ -567,19 +570,9 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
if (same_thread_group(p->real_parent, father))
return;
- /*
- * We don't want people slaying init.
- *
- * Note: we do this even if it is EXIT_DEAD, wait_task_zombie()
- * can change ->exit_state to EXIT_ZOMBIE. If this is the final
- * state, do_notify_parent() was already called and ->exit_signal
- * doesn't matter.
- */
+ /* We don't want people slaying init. */
p->exit_signal = SIGCHLD;
- if (p->exit_state == EXIT_DEAD)
- return;
-
/* 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)) {
@@ -1043,17 +1036,13 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
return wait_noreap_copyout(wo, p, pid, uid, why, status);
}
+ traced = ptrace_reparented(p);
/*
- * Try to move the task's state to DEAD
- * only one thread is allowed to do this:
+ * Move the task's state to DEAD/TRACE, only one thread can do this.
*/
- state = xchg(&p->exit_state, EXIT_DEAD);
- if (state != EXIT_ZOMBIE) {
- BUG_ON(state != EXIT_DEAD);
+ state = traced ? EXIT_TRACE : EXIT_DEAD;
+ if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
return 0;
- }
-
- traced = ptrace_reparented(p);
/*
* It can be ptraced but not reparented, check
* thread_group_leader() to filter out sub-threads.
@@ -1114,7 +1103,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
/*
* Now we are sure this task is interesting, and no other
- * thread can reap it because we set its state to EXIT_DEAD.
+ * thread can reap it because we its state == DEAD/TRACE.
*/
read_unlock(&tasklist_lock);
@@ -1159,14 +1148,14 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
* If this is not a sub-thread, notify the parent.
* If parent wants a zombie, don't release it now.
*/
+ state = EXIT_DEAD;
if (thread_group_leader(p) &&
- !do_notify_parent(p, p->exit_signal)) {
- p->exit_state = EXIT_ZOMBIE;
- p = NULL;
- }
+ !do_notify_parent(p, p->exit_signal))
+ state = EXIT_ZOMBIE;
+ p->exit_state = state;
write_unlock_irq(&tasklist_lock);
}
- if (p != NULL)
+ if (state == EXIT_DEAD)
release_task(p);
return retval;
@@ -1362,12 +1351,15 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
}
/* dead body doesn't have much to contribute */
- if (unlikely(p->exit_state == EXIT_DEAD)) {
+ if (unlikely(p->exit_state == EXIT_DEAD))
+ return 0;
+
+ if (unlikely(p->exit_state == EXIT_TRACE)) {
/*
- * But do not ignore this task until the tracer does
- * wait_task_zombie()->do_notify_parent().
+ * ptrace == 0 means we are the natural parent. In this case
+ * we should clear notask_error, debugger will notify us.
*/
- if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
+ if (likely(!ptrace))
wo->notask_error = 0;
return 0;
}