[NETLINK]: allocate group bitmaps dynamically

Allow changing the number of groups for a netlink family
after it has been created, use RCU to protect the listeners
bitmap keeping netlink_has_listeners() lock-free.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Patrick McHardy <kaber@trash.net>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 2e23353c28a5..b971ddd24090 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -161,6 +161,7 @@ extern struct sock *netlink_kernel_create(int unit, unsigned int groups,
                                           void (*input)(struct sock *sk, int len),
                                           struct mutex *cb_mutex,
                                           struct module *module);
+extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
 extern int netlink_has_listeners(struct sock *sk, unsigned int group);
 extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock);