From 48016dce46ad504a378849490bfb99c98be5cfaa Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
Date: Tue, 29 Nov 2016 10:52:48 -0500
Subject: [PATCH] xprtrdma: Avoid calls to ro_unmap_safe()

Micro-optimization: Most of the time, calls to ro_unmap_safe are
expensive no-ops. Call only when there is work to do.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 net/sunrpc/xprtrdma/transport.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index ed5e285fd2ea..545d3fc8de5a 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -621,7 +621,8 @@ xprt_rdma_free(struct rpc_task *task)
 
 	dprintk("RPC:       %s: called on 0x%p\n", __func__, req->rl_reply);
 
-	ia->ri_ops->ro_unmap_safe(r_xprt, req, !RPC_IS_ASYNC(task));
+	if (unlikely(!list_empty(&req->rl_registered)))
+		ia->ri_ops->ro_unmap_safe(r_xprt, req, !RPC_IS_ASYNC(task));
 	rpcrdma_unmap_sges(ia, req);
 	rpcrdma_buffer_put(req);
 }
@@ -657,7 +658,8 @@ xprt_rdma_send_request(struct rpc_task *task)
 	int rc = 0;
 
 	/* On retransmit, remove any previously registered chunks */
-	r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);
+	if (unlikely(!list_empty(&req->rl_registered)))
+		r_xprt->rx_ia.ri_ops->ro_unmap_safe(r_xprt, req, false);
 
 	rc = rpcrdma_marshal_req(rqst);
 	if (rc < 0)
-- 
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