connector: allow multiple messages to be sent in one packet

This increases the amount of bundling to reduce the number of packets
sent.  For the one wire use there can be multiple struct
w1_netlink_cmd in a struct w1_netlink_msg and multiple of those in
struct cn_msg, and with this change multiple of those in a struct
nlmsghdr, and at each level the len identifies there being multiple of
the next.

Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index b14f1d36f897..f612d68629dc 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c
@@ -43,6 +43,8 @@ static struct cn_dev cdev;
 static int cn_already_initialized;
 
 /*
+ * Sends mult (multiple) cn_msg at a time.
+ *
  * msg->seq and msg->ack are used to determine message genealogy.
  * When someone sends message it puts there locally unique sequence
  * and random acknowledge numbers.  Sequence number may be copied into
@@ -62,10 +64,13 @@ static int cn_already_initialized;
  * the acknowledgement number in the original message + 1, then it is
  * a new message.
  *
+ * If msg->len != len, then additional cn_msg messages are expected following
+ * the first msg.
+ *
  * The message is sent to, the portid if given, the group if given, both if
  * both, or if both are zero then the group is looked up and sent there.
  */
-int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
+int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
         gfp_t gfp_mask)
 {
         struct cn_callback_entry *__cbq;
@@ -98,7 +103,7 @@ int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
         if (!portid && !netlink_has_listeners(dev->nls, group))
                 return -ESRCH;
 
-        size = sizeof(*msg) + msg->len;
+        size = sizeof(*msg) + len;
 
         skb = nlmsg_new(size, gfp_mask);
         if (!skb)
@@ -121,6 +126,14 @@ int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
                                          gfp_mask);
         return netlink_unicast(dev->nls, skb, portid, !(gfp_mask&__GFP_WAIT));
 }
+EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
+
+/* same as cn_netlink_send_mult except msg->len is used for len */
+int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
+        gfp_t gfp_mask)
+{
+        return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask);
+}
 EXPORT_SYMBOL_GPL(cn_netlink_send);
 
 /*