genetlink: fix netns vs. netlink table locking

[linux-2.6.git] / net / netlink / af_netlink.c

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index d0ff382c40ca96cfe66752379039218714c966a1..c5aab6a368ce250badd33ab0d30e858292f91521 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -177,9 +177,11 @@ static void netlink_sock_destruct(struct sock *sk)
  * this, _but_ remember, it adds useless work on UP machines.
  */
 
-static void netlink_table_grab(void)
+void netlink_table_grab(void)
        __acquires(nl_table_lock)
 {
+       might_sleep();
+
        write_lock_irq(&nl_table_lock);
 
        if (atomic_read(&nl_table_users)) {
@@ -200,7 +202,7 @@ static void netlink_table_grab(void)
        }
 }
 
-static void netlink_table_ungrab(void)
+void netlink_table_ungrab(void)
        __releases(nl_table_lock)
 {
        write_unlock_irq(&nl_table_lock);
@@ -1549,37 +1551,21 @@ static void netlink_free_old_listeners(struct rcu_head *rcu_head)
        kfree(lrh->ptr);
 }
 
-/**
- * netlink_change_ngroups - change number of multicast groups
- *
- * This changes the number of multicast groups that are available
- * on a certain netlink family. Note that it is not possible to
- * change the number of groups to below 32. Also note that it does
- * not implicitly call netlink_clear_multicast_users() when the
- * number of groups is reduced.
- *
- * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
- * @groups: The new number of groups.
- */
-int netlink_change_ngroups(struct sock *sk, unsigned int groups)
+int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
 {
        unsigned long *listeners, *old = NULL;
        struct listeners_rcu_head *old_rcu_head;
        struct netlink_table *tbl = &nl_table[sk->sk_protocol];
-       int err = 0;
 
        if (groups < 32)
                groups = 32;
 
-       netlink_table_grab();
        if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
                listeners = kzalloc(NLGRPSZ(groups) +
                                    sizeof(struct listeners_rcu_head),
                                    GFP_ATOMIC);
-               if (!listeners) {
-                       err = -ENOMEM;
-                       goto out_ungrab;
-               }
+               if (!listeners)
+                       return -ENOMEM;
                old = tbl->listeners;
                memcpy(listeners, old, NLGRPSZ(tbl->groups));
                rcu_assign_pointer(tbl->listeners, listeners);
@@ -1597,8 +1583,29 @@ int netlink_change_ngroups(struct sock *sk, unsigned int groups)
        }
        tbl->groups = groups;
 
- out_ungrab:
+       return 0;
+}
+
+/**
+ * netlink_change_ngroups - change number of multicast groups
+ *
+ * This changes the number of multicast groups that are available
+ * on a certain netlink family. Note that it is not possible to
+ * change the number of groups to below 32. Also note that it does
+ * not implicitly call netlink_clear_multicast_users() when the
+ * number of groups is reduced.
+ *
+ * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
+ * @groups: The new number of groups.
+ */
+int netlink_change_ngroups(struct sock *sk, unsigned int groups)
+{
+       int err;
+
+       netlink_table_grab();
+       err = __netlink_change_ngroups(sk, groups);
        netlink_table_ungrab();
+
        return err;
 }