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-rw-r--r--include/linux/netlink.h4
-rw-r--r--net/netlink/af_netlink.c51
-rw-r--r--net/netlink/genetlink.c5
3 files changed, 37 insertions, 23 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 0fbecbb..080f6ba 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -176,12 +176,16 @@ struct netlink_skb_parms
#define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds)
+extern void netlink_table_grab(void);
+extern void netlink_table_ungrab(void);
+
extern struct sock *netlink_kernel_create(struct net *net,
int unit,unsigned int groups,
void (*input)(struct sk_buff *skb),
struct mutex *cb_mutex,
struct module *module);
extern void netlink_kernel_release(struct sock *sk);
+extern int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
extern void netlink_clear_multicast_users(struct sock *sk, unsigned int group);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index d0ff382..c5aab6a 100644
--- 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;
}
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 66f6ba0..566941e 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -176,9 +176,10 @@ int genl_register_mc_group(struct genl_family *family,
if (family->netnsok) {
struct net *net;
+ netlink_table_grab();
rcu_read_lock();
for_each_net_rcu(net) {
- err = netlink_change_ngroups(net->genl_sock,
+ err = __netlink_change_ngroups(net->genl_sock,
mc_groups_longs * BITS_PER_LONG);
if (err) {
/*
@@ -188,10 +189,12 @@ int genl_register_mc_group(struct genl_family *family,
* increased on some sockets which is ok.
*/
rcu_read_unlock();
+ netlink_table_ungrab();
goto out;
}
}
rcu_read_unlock();
+ netlink_table_ungrab();
} else {
err = netlink_change_ngroups(init_net.genl_sock,
mc_groups_longs * BITS_PER_LONG);