[PATCH] RPC: separate xprt_timer implementations

 Allow transports to hook the retransmit timer interrupt.  Some transports
 calculate their congestion window here so that a retransmit timeout has
 immediate effect on the congestion window.

 Test-plan:
 Use WAN simulation to cause sporadic bursty packet loss.  Look for significant
 regression in performance or client stability.

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 8589c1ad55e3..c3658ff027a6 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -860,6 +860,17 @@ static void xs_tcp_set_buffer_size(struct rpc_xprt *xprt)
         return;
 }
 
+/**
+ * xs_udp_timer - called when a retransmit timeout occurs on a UDP transport
+ * @task: task that timed out
+ *
+ * Adjust the congestion window after a retransmit timeout has occurred.
+ */
+static void xs_udp_timer(struct rpc_task *task)
+{
+        xprt_adjust_cwnd(task, -ETIMEDOUT);
+}
+
 static int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
 {
         struct sockaddr_in myaddr = {
@@ -1050,6 +1061,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
         .connect                = xs_connect,
         .send_request           = xs_udp_send_request,
         .set_retrans_timeout    = xprt_set_retrans_timeout_rtt,
+        .timer                  = xs_udp_timer,
         .close                  = xs_close,
         .destroy                = xs_destroy,
 };