2 files changed, 33 insertions, 13 deletions

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 536d0be3f61b..799cce6cbe45 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -51,6 +51,7 @@
 #include <linux/slab.h>
 #include <linux/prefetch.h>
 #include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/svc_rdma.h>
 #include <asm/bitops.h>
 #include <linux/module.h> /* try_module_get()/module_put() */
 
@@ -923,7 +924,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
 	}
 
 	INIT_LIST_HEAD(&buf->rb_recv_bufs);
-	for (i = 0; i < buf->rb_max_requests; i++) {
+	for (i = 0; i < buf->rb_max_requests + RPCRDMA_MAX_BC_REQUESTS; i++) {
 		struct rpcrdma_rep *rep;
 
 		rep = rpcrdma_create_rep(r_xprt);
@@ -1018,6 +1019,7 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
 		rep = rpcrdma_buffer_get_rep_locked(buf);
 		rpcrdma_destroy_rep(ia, rep);
 	}
+	buf->rb_send_count = 0;
 
 	spin_lock(&buf->rb_reqslock);
 	while (!list_empty(&buf->rb_allreqs)) {
@@ -1032,6 +1034,7 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
 		spin_lock(&buf->rb_reqslock);
 	}
 	spin_unlock(&buf->rb_reqslock);
+	buf->rb_recv_count = 0;
 
 	rpcrdma_destroy_mrs(buf);
 }
@@ -1074,8 +1077,27 @@ rpcrdma_put_mw(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mw *mw)
 	spin_unlock(&buf->rb_mwlock);
 }
 
+static struct rpcrdma_rep *
+rpcrdma_buffer_get_rep(struct rpcrdma_buffer *buffers)
+{
+	/* If an RPC previously completed without a reply (say, a
+	 * credential problem or a soft timeout occurs) then hold off
+	 * on supplying more Receive buffers until the number of new
+	 * pending RPCs catches up to the number of posted Receives.
+	 */
+	if (unlikely(buffers->rb_send_count < buffers->rb_recv_count))
+		return NULL;
+
+	if (unlikely(list_empty(&buffers->rb_recv_bufs)))
+		return NULL;
+	buffers->rb_recv_count++;
+	return rpcrdma_buffer_get_rep_locked(buffers);
+}
+
 /*
  * Get a set of request/reply buffers.
+ *
+ * Reply buffer (if available) is attached to send buffer upon return.
  */
 struct rpcrdma_req *
 rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
@@ -1085,21 +1107,15 @@ rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
 	spin_lock(&buffers->rb_lock);
 	if (list_empty(&buffers->rb_send_bufs))
 		goto out_reqbuf;
+	buffers->rb_send_count++;
 	req = rpcrdma_buffer_get_req_locked(buffers);
-	if (list_empty(&buffers->rb_recv_bufs))
-		goto out_repbuf;
-	req->rl_reply = rpcrdma_buffer_get_rep_locked(buffers);
+	req->rl_reply = rpcrdma_buffer_get_rep(buffers);
 	spin_unlock(&buffers->rb_lock);
 	return req;
 
 out_reqbuf:
 	spin_unlock(&buffers->rb_lock);
-	pr_warn("rpcrdma: out of request buffers (%p)\n", buffers);
-	return NULL;
-out_repbuf:
-	list_add(&req->rl_free, &buffers->rb_send_bufs);
-	spin_unlock(&buffers->rb_lock);
-	pr_warn("rpcrdma: out of reply buffers (%p)\n", buffers);
+	pr_warn("RPC:       %s: out of request buffers\n", __func__);
 	return NULL;
 }
 
@@ -1117,9 +1133,12 @@ rpcrdma_buffer_put(struct rpcrdma_req *req)
 	req->rl_reply = NULL;
 
 	spin_lock(&buffers->rb_lock);
+	buffers->rb_send_count--;
 	list_add_tail(&req->rl_free, &buffers->rb_send_bufs);
-	if (rep)
+	if (rep) {
+		buffers->rb_recv_count--;
 		list_add_tail(&rep->rr_list, &buffers->rb_recv_bufs);
+	}
 	spin_unlock(&buffers->rb_lock);
 }
 
@@ -1133,8 +1152,7 @@ rpcrdma_recv_buffer_get(struct rpcrdma_req *req)
 	struct rpcrdma_buffer *buffers = req->rl_buffer;
 
 	spin_lock(&buffers->rb_lock);
-	if (!list_empty(&buffers->rb_recv_bufs))
-		req->rl_reply = rpcrdma_buffer_get_rep_locked(buffers);
+	req->rl_reply = rpcrdma_buffer_get_rep(buffers);
 	spin_unlock(&buffers->rb_lock);
 }
 
@@ -1148,6 +1166,7 @@ rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
 	struct rpcrdma_buffer *buffers = &rep->rr_rxprt->rx_buf;
 
 	spin_lock(&buffers->rb_lock);
+	buffers->rb_recv_count--;
 	list_add_tail(&rep->rr_list, &buffers->rb_recv_bufs);
 	spin_unlock(&buffers->rb_lock);
 }
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 670fad57153a..a71b0f5897d8 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -321,6 +321,7 @@ struct rpcrdma_buffer {
 	char			*rb_pool;
 
 	spinlock_t		rb_lock;	/* protect buf lists */
+	int			rb_send_count, rb_recv_count;
 	struct list_head	rb_send_bufs;
 	struct list_head	rb_recv_bufs;
 	u32			rb_max_requests;