SUNRPC: Add tracepoint for socket errors

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index ab006b7..25dbfa9 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -837,6 +837,7 @@
 		goto out;
 	dprintk("RPC:       xs_error_report client %p, error=%d...\n",
 			xprt, -err);
+	trace_rpc_socket_error(xprt, sk->sk_socket, err);
 	xprt_wake_pending_tasks(xprt, err);
  out:
 	read_unlock_bh(&sk->sk_callback_lock);