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Commit d387f6ad authored by Thomas Graf's avatar Thomas Graf Committed by David S. Miller
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[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: default avatarThomas Graf <tgraf@suug.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2942e900

include/net/genetlink.h

+3 −2
Original line number Diff line number Diff line
@@ -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);

}



/**

include/net/netlink.h

+4 −2
Original line number Diff line number Diff line
@@ -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;

net/netlabel/netlabel_user.c

+1 −1
Original line number Diff line number Diff line
@@ -154,5 +154,5 @@ int netlbl_netlink_snd(struct sk_buff *skb, u32 pid) 
 */

int netlbl_netlink_snd_multicast(struct sk_buff *skb, u32 pid, u32 group)

{

	return genlmsg_multicast(skb, pid, group);

	return genlmsg_multicast(skb, pid, group, GFP_KERNEL);

}

net/netlink/af_netlink.c

+33 −1
Original line number Diff line number Diff line
@@ -1549,6 +1549,38 @@ void netlink_queue_skip(struct nlmsghdr *nlh, struct sk_buff *skb) 
	skb_pull(skb, msglen);

}



/**

 * nlmsg_notify - send a notification netlink message

 * @sk: netlink socket to use

 * @skb: notification message

 * @pid: destination netlink pid for reports or 0

 * @group: destination multicast group or 0

 * @report: 1 to report back, 0 to disable

 * @flags: allocation flags

 */

int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid,

		 unsigned int group, int report, gfp_t flags)

{

	int err = 0;



	if (group) {

		int exclude_pid = 0;



		if (report) {

			atomic_inc(&skb->users);

			exclude_pid = pid;

		}



		/* errors reported via destination sk->sk_err */

		nlmsg_multicast(sk, skb, exclude_pid, group, flags);

	}



	if (report)

		err = nlmsg_unicast(sk, skb, pid);



	return err;

}



#ifdef CONFIG_PROC_FS

struct nl_seq_iter {

	int link;
@@ -1802,4 +1834,4 @@ EXPORT_SYMBOL(netlink_set_err); 
EXPORT_SYMBOL(netlink_set_nonroot);

EXPORT_SYMBOL(netlink_unicast);

EXPORT_SYMBOL(netlink_unregister_notifier);

EXPORT_SYMBOL(nlmsg_notify);

net/netlink/genetlink.c

+1 −1
Original line number Diff line number Diff line
@@ -510,7 +510,7 @@ static int genl_ctrl_event(int event, void *data) 
		if (IS_ERR(msg))

			return PTR_ERR(msg);



		genlmsg_multicast(msg, 0, GENL_ID_CTRL);

		genlmsg_multicast(msg, 0, GENL_ID_CTRL, GFP_KERNEL);

		break;

	}