[NETLINK]: Add notification message sending interface

Adds nlmsg_notify() implementing proper notification logic. The
message is multicasted to all listeners in the group. The
applications the requests orignates from can request a unicast
back report in which case said socket will be excluded from the
multicast to avoid duplicated notifications.

nlmsg_multicast() is extended to take allocation flags to
allow notification in atomic contexts.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 7 insertions, 4 deletions

diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index 8c2287264266..97d6d3aba9d2 100644
--- a/include/net/genetlink.h
+++ b/include/net/genetlink.h
@@ -133,11 +133,12 @@ static inline int genlmsg_cancel(struct sk_buff *skb, void *hdr)
  * @skb: netlink message as socket buffer
  * @pid: own netlink pid to avoid sending to yourself
  * @group: multicast group id
+ * @flags: allocation flags
  */
 static inline int genlmsg_multicast(struct sk_buff *skb, u32 pid,
-                                    unsigned int group)
+                                    unsigned int group, gfp_t flags)
 {
-        return nlmsg_multicast(genl_sock, skb, pid, group);
+        return nlmsg_multicast(genl_sock, skb, pid, group, flags);
 }
 
 /**
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 3a5e40b1e045..b154b81d9a7a 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -43,6 +43,7 @@
  * Message Sending:
  *   nlmsg_multicast()                  multicast message to several groups
  *   nlmsg_unicast()                    unicast a message to a single socket
+ *   nlmsg_notify()                     send notification message
  *
  * Message Length Calculations:
  *   nlmsg_msg_size(payload)            length of message w/o padding
@@ -545,15 +546,16 @@ static inline void nlmsg_free(struct sk_buff *skb)
  * @skb: netlink message as socket buffer
  * @pid: own netlink pid to avoid sending to yourself
  * @group: multicast group id
+ * @flags: allocation flags
  */
 static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
-                                  u32 pid, unsigned int group)
+                                  u32 pid, unsigned int group, gfp_t flags)
 {
         int err;
 
         NETLINK_CB(skb).dst_group = group;
 
-        err = netlink_broadcast(sk, skb, pid, group, GFP_KERNEL);
+        err = netlink_broadcast(sk, skb, pid, group, flags);
         if (err > 0)
                 err = 0;