ipc: recompute msgmni on memory add / remove

[linux-2.6-block.git] / ipc / namespace.c

diff --git a/ipc/namespace.c b/ipc/namespace.c
index fe3c97aa99dc191f69c9febf058fc2b876204523..f7a35be2e7718ce72a1510fb80f301d7a7d77832 100644 (file)
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -26,6 +26,8 @@ static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
        msg_init_ns(ns);
        shm_init_ns(ns);
 
+       register_ipcns_notifier(ns);
+
        kref_init(&ns->kref);
        return ns;
 }
@@ -81,6 +83,15 @@ void free_ipc_ns(struct kref *kref)
        struct ipc_namespace *ns;
 
        ns = container_of(kref, struct ipc_namespace, kref);
+       /*
+        * Unregistering the hotplug notifier at the beginning guarantees
+        * that the ipc namespace won't be freed while we are inside the
+        * callback routine. Since the blocking_notifier_chain_XXX routines
+        * hold a rw lock on the notifier list, unregister_ipcns_notifier()
+        * won't take the rw lock before blocking_notifier_call_chain() has
+        * released the rd lock.
+        */
+       unregister_ipcns_notifier(ns);
        sem_exit_ns(ns);
        msg_exit_ns(ns);
        shm_exit_ns(ns);