From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=ham 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 095CEC0044C for ; Wed, 31 Oct 2018 23:32:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C288920664 for ; Wed, 31 Oct 2018 23:32:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="qGd8bb9x" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C288920664 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730694AbeKAIcj (ORCPT ); Thu, 1 Nov 2018 04:32:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:59584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730493AbeKAIJf (ORCPT ); Thu, 1 Nov 2018 04:09:35 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 20F7320843; Wed, 31 Oct 2018 23:09:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541027363; bh=/CwvahwV96iKOdOahg9iozHHRKRAOFxZxtm5qC/FAIE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qGd8bb9xl8GyHgm+GYwvyVhjA0TY0WIclw/Aue9QMC+Zu+oJy7a5hhsM4ewfXLgVR HUf4e+WhDwQgDfzCOUpN7WBHxe/8bf3mDdd1MtNLc19C5Ov+8j/qnChpp5Ol7swcBg EiNo5oRKJ4rzc1HiiuYsUesM04Yd1a8g6TgB7K4I= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Chuck Lever , stable@kernel.org, Anna Schumaker , Sasha Levin Subject: [PATCH AUTOSEL 4.18 098/126] xprtrdma: Reset credit grant properly after a disconnect Date: Wed, 31 Oct 2018 19:07:26 -0400 Message-Id: <20181031230754.29029-98-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181031230754.29029-1-sashal@kernel.org> References: <20181031230754.29029-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chuck Lever [ Upstream commit ef739b2175dde9c05594f768cb78149f1ce2ac36 ] On a fresh connection, an RPC/RDMA client is supposed to send only one RPC Call until it gets a credit grant in the first RPC Reply from the server [RFC 8166, Section 3.3.3]. There is a bug in the Linux client's credit accounting mechanism introduced by commit e7ce710a8802 ("xprtrdma: Avoid deadlock when credit window is reset"). On connect, it simply dumps all pending RPC Calls onto the new connection. Servers have been tolerant of this bad behavior. Currently no server implementation ever changes its credit grant over reconnects, and servers always repost enough Receives before connections are fully established. To correct this issue, ensure that the client resets both the credit grant _and_ the congestion window when handling a reconnect. Fixes: e7ce710a8802 ("xprtrdma: Avoid deadlock when credit ... ") Signed-off-by: Chuck Lever Cc: stable@kernel.org Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin --- net/sunrpc/xprtrdma/svc_rdma_backchannel.c | 1 + net/sunrpc/xprtrdma/transport.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c index a68180090554..b9827665ff35 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c +++ b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c @@ -248,6 +248,7 @@ static void xprt_rdma_bc_close(struct rpc_xprt *xprt) { dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); + xprt->cwnd = RPC_CWNDSHIFT; } static void diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index 143ce2579ba9..98cbc7b060ba 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -468,6 +468,12 @@ xprt_rdma_close(struct rpc_xprt *xprt) xprt->reestablish_timeout = 0; xprt_disconnect_done(xprt); rpcrdma_ep_disconnect(ep, ia); + + /* Prepare @xprt for the next connection by reinitializing + * its credit grant to one (see RFC 8166, Section 3.3.3). + */ + r_xprt->rx_buf.rb_credits = 1; + xprt->cwnd = RPC_CWNDSHIFT; } /** -- 2.17.1