diff options
authorChuck Lever <chuck.lever@oracle.com>2016-09-06 11:22:49 -0400
committerTrond Myklebust <trond.myklebust@primarydata.com>2016-09-06 15:59:35 -0400
commit78d506e1b7071b24850fd5ac22b896c459b0a04c (patch)
parent334a8f37115bf35e38617315a360a91ac4f2b2c6 (diff)
xprtrdma: Revert 3d4cf35bd4fa ("xprtrdma: Reply buffer exhaustion...")
Receive buffer exhaustion, if it were to actually occur, would be catastrophic. However, when there are no reply buffers to post, that means all of them have already been posted and are waiting for incoming replies. By design, there can never be more RPCs in flight than there are available receive buffers. A receive buffer can be left posted after an RPC exits without a received reply; say, due to a credential problem or a soft timeout. This does not result in fewer posted receive buffers than there are pending RPCs, and there is already logic in xprtrdma to deal appropriately with this case. It also looks like the "+ 2" that was removed was accidentally accommodating the number of extra receive buffers needed for receiving backchannel requests. That will need to be addressed by another patch. Fixes: 3d4cf35bd4fa ("xprtrdma: Reply buffer exhaustion can be...") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Anna Schumaker <Anna.Schumaker@Netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
1 files changed, 7 insertions, 5 deletions
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 536d0be3f61b..fefcba982415 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -923,7 +923,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
- for (i = 0; i < buf->rb_max_requests; i++) {
+ for (i = 0; i < buf->rb_max_requests + 2; i++) {
struct rpcrdma_rep *rep;
rep = rpcrdma_create_rep(r_xprt);
@@ -1076,6 +1076,8 @@ rpcrdma_put_mw(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mw *mw)
* 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)
@@ -1094,13 +1096,13 @@ rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
- pr_warn("rpcrdma: out of request buffers (%p)\n", buffers);
+ pr_warn("RPC: %s: out of request buffers\n", __func__);
return NULL;
- list_add(&req->rl_free, &buffers->rb_send_bufs);
- pr_warn("rpcrdma: out of reply buffers (%p)\n", buffers);
- return NULL;
+ pr_warn("RPC: %s: out of reply buffers\n", __func__);
+ req->rl_reply = NULL;
+ return req;