From patchwork Mon Apr 19 18:02:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 12212457 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45CC9C433ED for ; Mon, 19 Apr 2021 18:02:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B07A61246 for ; Mon, 19 Apr 2021 18:02:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240518AbhDSSDN (ORCPT ); Mon, 19 Apr 2021 14:03:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:41036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240510AbhDSSDM (ORCPT ); Mon, 19 Apr 2021 14:03:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3C20061107; Mon, 19 Apr 2021 18:02:42 +0000 (UTC) Subject: [PATCH v3 10/26] xprtrdma: Fix cwnd update ordering From: Chuck Lever To: trondmy@hammerspace.com Cc: linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org Date: Mon, 19 Apr 2021 14:02:41 -0400 Message-ID: <161885536143.38598.9604745938847259595.stgit@manet.1015granger.net> In-Reply-To: <161885481568.38598.16682844600209775665.stgit@manet.1015granger.net> References: <161885481568.38598.16682844600209775665.stgit@manet.1015granger.net> User-Agent: StGit/0.23-29-ga622f1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org After a reconnect, the reply handler is opening the cwnd (and thus enabling more RPC Calls to be sent) /before/ rpcrdma_post_recvs() can post enough Receive WRs to receive their replies. This causes an RNR and the new connection is lost immediately. The race is most clearly exposed when KASAN and disconnect injection are enabled. This slows down rpcrdma_rep_create() enough to allow the send side to post a bunch of RPC Calls before the Receive completion handler can invoke ib_post_recv(). Fixes: 2ae50ad68cd7 ("xprtrdma: Close window between waking RPC senders and posting Receives") Signed-off-by: Chuck Lever --- net/sunrpc/xprtrdma/rpc_rdma.c | 3 ++- net/sunrpc/xprtrdma/verbs.c | 10 +++++----- net/sunrpc/xprtrdma/xprt_rdma.h | 2 +- 3 files changed, 8 insertions(+), 7 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 292f066d006e..21ddd78a8c35 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -1430,9 +1430,10 @@ void rpcrdma_reply_handler(struct rpcrdma_rep *rep) credits = 1; /* don't deadlock */ else if (credits > r_xprt->rx_ep->re_max_requests) credits = r_xprt->rx_ep->re_max_requests; + rpcrdma_post_recvs(r_xprt, credits + (buf->rb_bc_srv_max_requests << 1), + false); if (buf->rb_credits != credits) rpcrdma_update_cwnd(r_xprt, credits); - rpcrdma_post_recvs(r_xprt, false); req = rpcr_to_rdmar(rqst); if (unlikely(req->rl_reply)) diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 0ade69501061..5a2871c4561f 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -544,7 +544,7 @@ int rpcrdma_xprt_connect(struct rpcrdma_xprt *r_xprt) * outstanding Receives. */ rpcrdma_ep_get(ep); - rpcrdma_post_recvs(r_xprt, true); + rpcrdma_post_recvs(r_xprt, 1, true); rc = rdma_connect(ep->re_id, &ep->re_remote_cma); if (rc) @@ -1395,21 +1395,21 @@ int rpcrdma_post_sends(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) /** * rpcrdma_post_recvs - Refill the Receive Queue * @r_xprt: controlling transport instance - * @temp: mark Receive buffers to be deleted after use + * @needed: current credit grant + * @temp: mark Receive buffers to be deleted after one use * */ -void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp) +void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp) { struct rpcrdma_buffer *buf = &r_xprt->rx_buf; struct rpcrdma_ep *ep = r_xprt->rx_ep; struct ib_recv_wr *wr, *bad_wr; struct rpcrdma_rep *rep; - int needed, count, rc; + int count, rc; rc = 0; count = 0; - needed = buf->rb_credits + (buf->rb_bc_srv_max_requests << 1); if (likely(ep->re_receive_count > needed)) goto out; needed -= ep->re_receive_count; diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h index 31404326f29f..2504f67af63e 100644 --- a/net/sunrpc/xprtrdma/xprt_rdma.h +++ b/net/sunrpc/xprtrdma/xprt_rdma.h @@ -462,7 +462,7 @@ int rpcrdma_xprt_connect(struct rpcrdma_xprt *r_xprt); void rpcrdma_xprt_disconnect(struct rpcrdma_xprt *r_xprt); int rpcrdma_post_sends(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req); -void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp); +void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp); /* * Buffer calls - xprtrdma/verbs.c