[PATCH v1 3/6] xprtrdma: Initialize rb_credits in one place

[Chuck Lever <chuck.lever@xxxxxxxxxx>]

Clean up/code de-duplication.

Nit: RPC_CWNDSHIFT is incorrect as the initial value for xprt->cwnd.
This mistake does not appear to have operational consequences, since
the cwnd value is replaced with a valid value upon the first Receive
completion.

Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 net/sunrpc/xprtrdma/rpc_rdma.c  |   42 +++++++++++++++++++++++++++++++++------
 net/sunrpc/xprtrdma/transport.c |    9 --------
 net/sunrpc/xprtrdma/verbs.c     |    2 +-
 net/sunrpc/xprtrdma/xprt_rdma.h |    1 +
 4 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index b86b5fd..f1e3639 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -916,6 +916,40 @@ static bool rpcrdma_prepare_msg_sges(struct rpcrdma_xprt *r_xprt,
 	return ret;
 }
 
+static void __rpcrdma_update_cwnd_locked(struct rpc_xprt *xprt,
+					 struct rpcrdma_buffer *buf,
+					 u32 grant)
+{
+	buf->rb_credits = grant;
+	xprt->cwnd = grant << RPC_CWNDSHIFT;
+}
+
+static void rpcrdma_update_cwnd(struct rpcrdma_xprt *r_xprt, u32 grant)
+{
+	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
+
+	spin_lock(&xprt->transport_lock);
+	__rpcrdma_update_cwnd_locked(xprt, &r_xprt->rx_buf, grant);
+	spin_unlock(&xprt->transport_lock);
+}
+
+/**
+ * rpcrdma_reset_cwnd - Reset the xprt's congestion window
+ * @r_xprt: controlling transport instance
+ *
+ * Prepare @r_xprt for the next connection by reinitializing
+ * its credit grant to one (see RFC 8166, Section 3.3.3).
+ */
+void rpcrdma_reset_cwnd(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
+
+	spin_lock(&xprt->transport_lock);
+	xprt->cong = 0;
+	__rpcrdma_update_cwnd_locked(xprt, &r_xprt->rx_buf, 1);
+	spin_unlock(&xprt->transport_lock);
+}
+
 /**
  * rpcrdma_inline_fixup - Scatter inline received data into rqst's iovecs
  * @rqst: controlling RPC request
@@ -1356,12 +1390,8 @@ void rpcrdma_reply_handler(struct rpcrdma_rep *rep)
 		credits = 1;	/* don't deadlock */
 	else if (credits > buf->rb_max_requests)
 		credits = buf->rb_max_requests;
-	if (buf->rb_credits != credits) {
-		spin_lock(&xprt->transport_lock);
-		buf->rb_credits = credits;
-		xprt->cwnd = credits << RPC_CWNDSHIFT;
-		spin_unlock(&xprt->transport_lock);
-	}
+	if (buf->rb_credits != credits)
+		rpcrdma_update_cwnd(r_xprt, credits);
 
 	req = rpcr_to_rdmar(rqst);
 	if (req->rl_reply) {
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index c67d465..0711308 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -425,15 +425,6 @@ void xprt_rdma_close(struct rpc_xprt *xprt)
 		return;
 	rpcrdma_ep_disconnect(ep, ia);
 
-	/* Prepare @xprt for the next connection by reinitializing
-	 * its credit grant to one (see RFC 8166, Section 3.3.3).
-	 */
-	spin_lock(&xprt->transport_lock);
-	r_xprt->rx_buf.rb_credits = 1;
-	xprt->cong = 0;
-	xprt->cwnd = RPC_CWNDSHIFT;
-	spin_unlock(&xprt->transport_lock);
-
 out:
 	xprt->reestablish_timeout = 0;
 	++xprt->connect_cookie;
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index f4b1365..97bc15e 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -727,6 +727,7 @@ static int rpcrdma_ep_reconnect(struct rpcrdma_xprt *r_xprt,
 	ep->rep_connected = 0;
 	xprt_clear_connected(xprt);
 
+	rpcrdma_reset_cwnd(r_xprt);
 	rpcrdma_post_recvs(r_xprt, true);
 
 	rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
@@ -1163,7 +1164,6 @@ int rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
 		list_add(&req->rl_list, &buf->rb_send_bufs);
 	}
 
-	buf->rb_credits = 1;
 	init_llist_head(&buf->rb_free_reps);
 
 	rc = rpcrdma_sendctxs_create(r_xprt);
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 65e6b0e..b170cf5 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -576,6 +576,7 @@ int rpcrdma_prepare_send_sges(struct rpcrdma_xprt *r_xprt,
 void rpcrdma_sendctx_unmap(struct rpcrdma_sendctx *sc);
 int rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst);
 void rpcrdma_set_max_header_sizes(struct rpcrdma_xprt *);
+void rpcrdma_reset_cwnd(struct rpcrdma_xprt *r_xprt);
 void rpcrdma_complete_rqst(struct rpcrdma_rep *rep);
 void rpcrdma_reply_handler(struct rpcrdma_rep *rep);