[PATCH v1 6/8] xprtrdma: Improve locking around rpcrdma_rep creation

[Chuck Lever <chuck.lever@oracle.com>]

Serialize the use of the rb_all_reps list during rep creation and
destruction.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index b68fc81a78fb..2fde805edb64 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -956,13 +956,11 @@ static void rpcrdma_reqs_reset(struct rpcrdma_xprt *r_xprt)
 		rpcrdma_req_reset(req);
 }
 
-/* No locking needed here. This function is called only by the
- * Receive completion handler.
- */
 static noinline
 struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
 				       bool temp)
 {
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
 	struct rpcrdma_rep *rep;
 
 	rep = kzalloc(sizeof(*rep), GFP_KERNEL);
@@ -989,7 +987,10 @@ struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
 	rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
 	rep->rr_recv_wr.num_sge = 1;
 	rep->rr_temp = temp;
-	list_add(&rep->rr_all, &r_xprt->rx_buf.rb_all_reps);
+
+	spin_lock(&buf->rb_lock);
+	list_add(&rep->rr_all, &buf->rb_all_reps);
+	spin_unlock(&buf->rb_lock);
 	return rep;
 
 out_free_regbuf: