Revert "Revert "rsocket: Change keepalive to 0-byte RDMA write""

This reverts commit a34703c53259845dd20450a87eb6747030e23e8b.

0-byte RDMA writes appears to be working correctly with
HCAs from 2 different vendors.  The original problem that
was reported turned out to be a user error.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>

diff --git a/src/rsocket.c b/src/rsocket.c
index b869d889536629734ff28c721a0fa5fd639e7b49..c7a0cb2a06d8e53407858049bcd2820344a0d0c2 100644 (file)
--- a/src/rsocket.c
+++ b/src/rsocket.c
@@ -156,6 +156,7 @@ enum {
 
 enum {
        RS_CTRL_DISCONNECT,
+       RS_CTRL_KEEPALIVE,
        RS_CTRL_SHUTDOWN
 };
 
@@ -4243,18 +4244,17 @@ static void tcp_svc_process_sock(struct rs_svc *svc)
 }
 
 /*
- * Send a credit update as the keep-alive message.  We may or may not have
- * any credits, but if we do, then we require a minimum of 2 control credits
- * for protocols that do not support RDMA write with immediate data.  There's
- * no need to send a keep-alive message if we have any messages outstanding,
- * and we start with a minimum of 2 credits.  For simplicity, we just check
- * that both credits are available before sending the keep-alive.
+ * Send a 0 byte RDMA write with immediate as keep-alive message.
+ * This avoids the need for the receive side to do any acknowledgment.
  */
 static void tcp_svc_send_keepalive(struct rsocket *rs)
 {
        fastlock_acquire(&rs->cq_lock);
-       if (rs_2ctrl_avail(rs) && (rs->state & rs_connected))
-               rs_send_credits(rs);
+       if (rs_ctrl_avail(rs) && (rs->state & rs_connected)) {
+               rs->ctrl_seqno++;
+               rs_post_write(rs, NULL, 0, rs_msg_set(RS_OP_CTRL, RS_CTRL_KEEPALIVE),
+                             0, (uint64_t) NULL, (uint64_t) NULL);
+       }
        fastlock_release(&rs->cq_lock);
 }