ipc: recompute msgmni on ipc namespace creation/removal

[safe/jmp/linux-2.6] / ipc / namespace.c

diff --git a/ipc/namespace.c b/ipc/namespace.c
index 1fed892..9171d94 100644 (file)
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -20,10 +20,20 @@ static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
        if (ns == NULL)
                return ERR_PTR(-ENOMEM);
 
+       atomic_inc(&nr_ipc_ns);
+
        sem_init_ns(ns);
        msg_init_ns(ns);
        shm_init_ns(ns);
 
+       /*
+        * msgmni has already been computed for the new ipc ns.
+        * Thus, do the ipcns creation notification before registering that
+        * new ipcns in the chain.
+        */
+       ipcns_notify(IPCNS_CREATED);
+       register_ipcns_notifier(ns);
+
        kref_init(&ns->kref);
        return ns;
 }
@@ -44,13 +54,59 @@ struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
        return new_ns;
 }
 
+/*
+ * free_ipcs - free all ipcs of one type
+ * @ns:   the namespace to remove the ipcs from
+ * @ids:  the table of ipcs to free
+ * @free: the function called to free each individual ipc
+ *
+ * Called for each kind of ipc when an ipc_namespace exits.
+ */
+void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
+              void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
+{
+       struct kern_ipc_perm *perm;
+       int next_id;
+       int total, in_use;
+
+       down_write(&ids->rw_mutex);
+
+       in_use = ids->in_use;
+
+       for (total = 0, next_id = 0; total < in_use; next_id++) {
+               perm = idr_find(&ids->ipcs_idr, next_id);
+               if (perm == NULL)
+                       continue;
+               ipc_lock_by_ptr(perm);
+               free(ns, perm);
+               total++;
+       }
+       up_write(&ids->rw_mutex);
+}
+
 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);
        kfree(ns);
+       atomic_dec(&nr_ipc_ns);
+
+       /*
+        * Do the ipcns removal notification after decrementing nr_ipc_ns in
+        * order to have a correct value when recomputing msgmni.
+        */
+       ipcns_notify(IPCNS_REMOVED);
 }