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Subject: [PATCH 17/23] pid: Add pid namespaces into ns_idr
From:   Kirill Tkhai <ktkhai@virtuozzo.com>
To:     viro@zeniv.linux.org.uk, adobriyan@gmail.com, davem@davemloft.net,
        ebiederm@xmission.com, akpm@linux-foundation.org,
        christian.brauner@ubuntu.com, areber@redhat.com, serge@hallyn.com,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        ktkhai@virtuozzo.com
Date:   Thu, 30 Jul 2020 15:00:51 +0300
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Now they are exposed in /proc/namespace/ directory.

Note, that we already wait RCU grace period before
pid namespace's memory is freed.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 kernel/pid_namespace.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index da8490390f51..06398a7c4c59 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -109,8 +109,13 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
 	ns->ucounts = ucounts;
 	ns->pid_allocated = PIDNS_ADDING;
 
+	if (ns_idr_register(&ns->ns) < 0)
+		goto out_free_inum;
+
 	return ns;
 
+out_free_inum:
+	ns_free_inum(&ns->ns);
 out_free_idr:
 	idr_destroy(&ns->idr);
 	kmem_cache_free(pid_ns_cachep, ns);
@@ -132,6 +137,7 @@ static void delayed_free_pidns(struct rcu_head *p)
 
 static void destroy_pid_namespace(struct pid_namespace *ns)
 {
+	ns_idr_unregister(&ns->ns);
 	ns_free_inum(&ns->ns);
 
 	idr_destroy(&ns->idr);
@@ -466,6 +472,7 @@ static __init int pid_namespaces_init(void)
 #ifdef CONFIG_CHECKPOINT_RESTORE
 	register_sysctl_paths(kern_path, pid_ns_ctl_table);
 #endif
+	WARN_ON(ns_idr_register(&init_pid_ns.ns) < 0);
 	return 0;
 }