Return-Path: Received: from mail-pf0-f193.google.com ([209.85.192.193]:34151 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760243AbcCDQ2a (ORCPT ); Fri, 4 Mar 2016 11:28:30 -0500 Subject: [PATCH v3 08/11] xprtrdma: Serialize credit accounting again From: Chuck Lever To: anna.schumaker@netapp.com Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org Date: Fri, 04 Mar 2016 11:28:27 -0500 Message-ID: <20160304162827.13590.44906.stgit@oracle120-ib.cthon.org> In-Reply-To: <20160304162447.13590.9524.stgit@oracle120-ib.cthon.org> References: <20160304162447.13590.9524.stgit@oracle120-ib.cthon.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Commit fe97b47cd623 ("xprtrdma: Use workqueue to process RPC/RDMA replies") replaced the reply tasklet with a workqueue that allows RPC replies to be processed in parallel. Thus the credit values in RPC-over-RDMA replies can be applied in a different order than in which the server sent them. To fix this, revert commit eba8ff660b2d ("xprtrdma: Move credit update to RPC reply handler"). Reverting is done by hand to accommodate code changes that have occurred since then. Fixes: fe97b47cd623 ("xprtrdma: Use workqueue to process . . .") Signed-off-by: Chuck Lever --- net/sunrpc/xprtrdma/rpc_rdma.c | 9 +-------- net/sunrpc/xprtrdma/verbs.c | 27 ++++++++++++++++++++++++++- net/sunrpc/xprtrdma/xprt_rdma.h | 1 + 3 files changed, 28 insertions(+), 9 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 35f8108..888823b 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -797,7 +797,6 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep) __be32 *iptr; int rdmalen, status, rmerr; unsigned long cwnd; - u32 credits; dprintk("RPC: %s: incoming rep %p\n", __func__, rep); @@ -928,15 +927,9 @@ out: if (req->rl_nchunks) r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt, req); - credits = be32_to_cpu(headerp->rm_credit); - if (credits == 0) - credits = 1; /* don't deadlock */ - else if (credits > r_xprt->rx_buf.rb_max_requests) - credits = r_xprt->rx_buf.rb_max_requests; - spin_lock_bh(&xprt->transport_lock); cwnd = xprt->cwnd; - xprt->cwnd = credits << RPC_CWNDSHIFT; + xprt->cwnd = atomic_read(&r_xprt->rx_buf.rb_credits) << RPC_CWNDSHIFT; if (xprt->cwnd > cwnd) xprt_release_rqst_cong(rqst->rq_task); diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 878f1bf..fc1ef5f 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -190,6 +190,28 @@ rpcrdma_receive_worker(struct work_struct *work) rpcrdma_reply_handler(rep); } +/* Perform basic sanity checking to avoid using garbage + * to update the credit grant value. + */ +static void +rpcrdma_update_granted_credits(struct rpcrdma_rep *rep) +{ + struct rpcrdma_msg *rmsgp = rdmab_to_msg(rep->rr_rdmabuf); + struct rpcrdma_buffer *buffer = &rep->rr_rxprt->rx_buf; + u32 credits; + + if (rep->rr_len < RPCRDMA_HDRLEN_ERR) + return; + + credits = be32_to_cpu(rmsgp->rm_credit); + if (credits == 0) + credits = 1; /* don't deadlock */ + else if (credits > buffer->rb_max_requests) + credits = buffer->rb_max_requests; + + atomic_set(&buffer->rb_credits, credits); +} + static void rpcrdma_recvcq_process_wc(struct ib_wc *wc) { @@ -211,7 +233,8 @@ rpcrdma_recvcq_process_wc(struct ib_wc *wc) ib_dma_sync_single_for_cpu(rep->rr_device, rdmab_addr(rep->rr_rdmabuf), rep->rr_len, DMA_FROM_DEVICE); - prefetch(rdmab_to_msg(rep->rr_rdmabuf)); + + rpcrdma_update_granted_credits(rep); out_schedule: queue_work(rpcrdma_receive_wq, &rep->rr_work); @@ -330,6 +353,7 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event) connected: dprintk("RPC: %s: %sconnected\n", __func__, connstate > 0 ? "" : "dis"); + atomic_set(&xprt->rx_buf.rb_credits, 1); ep->rep_connected = connstate; rpcrdma_conn_func(ep); wake_up_all(&ep->rep_connect_wait); @@ -943,6 +967,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt) buf->rb_max_requests = r_xprt->rx_data.max_requests; buf->rb_bc_srv_max_requests = 0; spin_lock_init(&buf->rb_lock); + atomic_set(&buf->rb_credits, 1); rc = ia->ri_ops->ro_init(r_xprt); if (rc) diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index 38fe11b..7bf6f43 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -311,6 +311,7 @@ struct rpcrdma_buffer { struct list_head rb_send_bufs; struct list_head rb_recv_bufs; u32 rb_max_requests; + atomic_t rb_credits; /* most recent credit grant */ u32 rb_bc_srv_max_requests; spinlock_t rb_reqslock; /* protect rb_allreqs */