From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Looking at pid_ns->nr_hashed is a bit simpler and it works for
disjoint process trees that an unshare or a join of a pid_namespace
may create.
Acked-by: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
kernel/exit.c | 12 ------------
kernel/pid.c | 16 +++++++++++++---
kernel/pid_namespace.c | 15 ++++-----------
3 files changed, 17 insertions(+), 26 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 346616c..d7fe58d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -72,18 +72,6 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
list_del_rcu(&p->tasks);
list_del_init(&p->sibling);
__this_cpu_dec(process_counts);
- /*
- * If we are the last child process in a pid namespace to be
- * reaped, notify the reaper sleeping zap_pid_ns_processes().
- */
- if (IS_ENABLED(CONFIG_PID_NS)) {
- struct task_struct *parent = p->real_parent;
-
- if ((task_active_pid_ns(parent)->child_reaper == parent) &&
- list_empty(&parent->children) &&
- (parent->flags & PF_EXITING))
- wake_up_process(parent);
- }
}
list_del_rcu(&p->thread_group);
}
diff --git a/kernel/pid.c b/kernel/pid.c
index 9c21911..6e8da29 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -273,10 +273,20 @@ void free_pid(struct pid *pid)
spin_lock_irqsave(&pidmap_lock, flags);
for (i = 0; i <= pid->level; i++) {
struct upid *upid = pid->numbers + i;
+ struct pid_namespace *ns = upid->ns;
hlist_del_rcu(&upid->pid_chain);
- if (--upid->ns->nr_hashed == 0) {
- upid->ns->nr_hashed = -1;
- schedule_work(&upid->ns->proc_work);
+ switch(--ns->nr_hashed) {
+ case 1:
+ /* When all that is left in the pid namespace
+ * is the reaper wake up the reaper. The reaper
+ * may be sleeping in zap_pid_ns_processes().
+ */
+ wake_up_process(ns->child_reaper);
+ break;
+ case 0:
+ ns->nr_hashed = -1;
+ schedule_work(&ns->proc_work);
+ break;
}
}
spin_unlock_irqrestore(&pidmap_lock, flags);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index cc44db7..e106b18 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -216,22 +216,15 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
/*
* sys_wait4() above can't reap the TASK_DEAD children.
- * Make sure they all go away, see __unhash_process().
+ * Make sure they all go away, see free_pid().
*/
for (;;) {
- bool need_wait = false;
-
- read_lock(&tasklist_lock);
- if (!list_empty(¤t->children)) {
- __set_current_state(TASK_UNINTERRUPTIBLE);
- need_wait = true;
- }
- read_unlock(&tasklist_lock);
-
- if (!need_wait)
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (pid_ns->nr_hashed == 1)
break;
schedule();
}
+ __set_current_state(TASK_RUNNING);
if (pid_ns->reboot)
current->signal->group_exit_code = pid_ns->reboot;
--
1.7.5.4
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