From: Chuck Lever chuck.lever@oracle.com
commit 2ae50ad68cd79224198b525f7bd645c9da98b6ff upstream.
A recent clean up attempted to separate Receive handling and RPC Reply processing, in the name of clean layering.
Unfortunately, we can't do this because the Receive Queue has to be refilled _after_ the most recent credit update from the responder is parsed from the transport header, but _before_ we wake up the next RPC sender. That is right in the middle of rpcrdma_reply_handler().
Usually this isn't a problem because current responder implementations don't vary their credit grant. The one exception is when a connection is established: the grant goes from one to a much larger number on the first Receive. The requester MUST post enough Receives right then so that any outstanding requests can be sent without risking RNR and connection loss.
Fixes: 6ceea36890a0 ("xprtrdma: Refactor Receive accounting") Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/sunrpc/xprtrdma/rpc_rdma.c | 1 + net/sunrpc/xprtrdma/verbs.c | 11 +++++++---- net/sunrpc/xprtrdma/xprt_rdma.h | 1 + 3 files changed, 9 insertions(+), 4 deletions(-)
--- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -1362,6 +1362,7 @@ void rpcrdma_reply_handler(struct rpcrdm xprt->cwnd = credits << RPC_CWNDSHIFT; spin_unlock(&xprt->transport_lock); } + rpcrdma_post_recvs(r_xprt, false);
req = rpcr_to_rdmar(rqst); if (req->rl_reply) { --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -84,7 +84,6 @@ rpcrdma_regbuf_alloc(size_t size, enum d gfp_t flags); static void rpcrdma_regbuf_dma_unmap(struct rpcrdma_regbuf *rb); static void rpcrdma_regbuf_free(struct rpcrdma_regbuf *rb); -static void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp);
/* Wait for outstanding transport work to finish. ib_drain_qp * handles the drains in the wrong order for us, so open code @@ -170,7 +169,6 @@ rpcrdma_wc_receive(struct ib_cq *cq, str rdmab_addr(rep->rr_rdmabuf), wc->byte_len, DMA_FROM_DEVICE);
- rpcrdma_post_recvs(r_xprt, false); rpcrdma_reply_handler(rep); return;
@@ -1478,8 +1476,13 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia, return 0; }
-static void -rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp) +/** + * rpcrdma_post_recvs - Refill the Receive Queue + * @r_xprt: controlling transport instance + * @temp: mark Receive buffers to be deleted after use + * + */ +void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp) { struct rpcrdma_buffer *buf = &r_xprt->rx_buf; struct rpcrdma_ep *ep = &r_xprt->rx_ep; --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -474,6 +474,7 @@ void rpcrdma_ep_disconnect(struct rpcrdm
int rpcrdma_ep_post(struct rpcrdma_ia *, struct rpcrdma_ep *, struct rpcrdma_req *); +void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp);
/* * Buffer calls - xprtrdma/verbs.c