[CONNECTOR]: Use netlink_has_listeners() to avoind unnecessary allocations.

Return -ESRCH from cn_netlink_send() when there are not listeners, just as it could be done by netlink_broadcast(). Propagate netlink_broadcast() error back to the caller. Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: David S. Miller <davem@davemloft.net>

[CONNECTOR]: Use netlink_has_listeners() to avoind unnecessary allocations.
Return -ESRCH from cn_netlink_send() when there are not listeners, just as it could be done by netlink_broadcast(). Propagate netlink_broadcast() error back to the caller. Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: David S. Miller <davem@davemloft.net>
Evgeniy Polyakov · David S. Miller
1 parent 0ac81ae34e
Showing 2 changed files with 7 additions and 5 deletions Side-by-side Diff
Documentation/connector/connector.txt
drivers/connector/connector.c
@@ -69,10 +69,11 @@
  
 struct cb_id *id 		- unique connector's user identifier.
  
-void cn_netlink_send(struct cn_msg *msg, u32 __groups, int gfp_mask);
+int cn_netlink_send(struct cn_msg *msg, u32 __groups, int gfp_mask);
  
 Sends message to the specified groups.  It can be safely called from
-any context, but may silently fail under strong memory pressure.
+softirq context, but may silently fail under strong memory pressure.
+If there are no listeners for given group -ESRCH can be returned.
  
 struct cn_msg *			- message header(with attached data).
 u32 __group			- destination group.
@@ -97,6 +97,9 @@
 		group = __group;
 	}
  
+	if (!netlink_has_listeners(dev->nls, group))
+		return -ESRCH;
+
 	size = NLMSG_SPACE(sizeof(*msg) + msg->len);
  
 	skb = alloc_skb(size, gfp_mask);
@@ -111,9 +114,7 @@
  
 	NETLINK_CB(skb).dst_group = group;
  
-	netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
-
-	return 0;
+	return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
  
 nlmsg_failure:
 	kfree_skb(skb);
...	...	@@ -69,10 +69,11 @@
69	69
70	70	struct cb_id *id - unique connector's user identifier.
71	71
72		-void cn_netlink_send(struct cn_msg *msg, u32 __groups, int gfp_mask);
	72	+int cn_netlink_send(struct cn_msg *msg, u32 __groups, int gfp_mask);
73	73
74	74	Sends message to the specified groups. It can be safely called from
75		-any context, but may silently fail under strong memory pressure.
	75	+softirq context, but may silently fail under strong memory pressure.
	76	+If there are no listeners for given group -ESRCH can be returned.
76	77
77	78	struct cn_msg * - message header(with attached data).
78	79	u32 __group - destination group.
...	...	@@ -97,6 +97,9 @@
97	97	group = __group;
98	98	}
99	99
	100	+ if (!netlink_has_listeners(dev->nls, group))
	101	+ return -ESRCH;
	102	+
100	103	size = NLMSG_SPACE(sizeof(*msg) + msg->len);
101	104
102	105	skb = alloc_skb(size, gfp_mask);
...	...	@@ -111,9 +114,7 @@
111	114
112	115	NETLINK_CB(skb).dst_group = group;
113	116
114		- netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
115		-
116		- return 0;
	117	+ return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
117	118
118	119	nlmsg_failure:
119	120	kfree_skb(skb);