ipvs: add support for sync threads

	Allow master and backup servers to use many threads
for sync traffic. Add sysctl var "sync_ports" to define the
number of threads. Every thread will use single UDP port,
thread 0 will use the default port 8848 while last thread
will use port 8848+sync_ports-1.

	The sync traffic for connections is scheduled to many
master threads based on the cp address but one connection is
always assigned to same thread to avoid reordering of the
sync messages.

	Remove ip_vs_sync_switch_mode because this check
for sync mode change is still risky. Instead, check for mode
change under sync_buff_lock.

	Make sure the backup socks do not block on reading.

Special thanks to Aleksey Chudov for helping in all tests.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Tested-by: Aleksey Chudov <aleksey.chudov@gmail.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 4f3205d..c7edf20 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -619,12 +619,19 @@ struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp)
 	if (dest) {
 		struct ip_vs_proto_data *pd;
 
+		spin_lock(&cp->lock);
+		if (cp->dest) {
+			spin_unlock(&cp->lock);
+			return dest;
+		}
+
 		/* Applications work depending on the forwarding method
 		 * but better to reassign them always when binding dest */
 		if (cp->app)
 			ip_vs_unbind_app(cp);
 
 		ip_vs_bind_dest(cp, dest);
+		spin_unlock(&cp->lock);
 
 		/* Update its packet transmitter */
 		cp->packet_xmit = NULL;