From patchwork Wed Jul 14 15:50:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever III X-Patchwork-Id: 12377389 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=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 D8699C07E9C for ; Wed, 14 Jul 2021 15:50:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0F47613C8 for ; Wed, 14 Jul 2021 15:50:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239652AbhGNPx2 (ORCPT ); Wed, 14 Jul 2021 11:53:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:41212 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239554AbhGNPx2 (ORCPT ); Wed, 14 Jul 2021 11:53:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 45662613C5 for ; Wed, 14 Jul 2021 15:50:36 +0000 (UTC) Subject: [PATCH RFC 4/4] SUNRPC: Unset RPC_TASK_NO_RETRANS_TIMEOUT for NULL RPCs From: Chuck Lever To: linux-nfs@vger.kernel.org Date: Wed, 14 Jul 2021 11:50:35 -0400 Message-ID: <162627783556.1294.4875890480589342085.stgit@manet.1015granger.net> In-Reply-To: <162627611661.1294.9189768423517916152.stgit@manet.1015granger.net> References: <162627611661.1294.9189768423517916152.stgit@manet.1015granger.net> User-Agent: StGit/1.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org In some rare failure modes, the server is actually reading the transport, but then just dropping the requests on the floor. TCP_USER_TIMEOUT cannot detect that case. Prevent such a stuck server from pinning client resources indefinitely by ensuring that certain idempotent requests (such as NULL) can time out even if the connection is still operational. Otherwise rpc_bind_new_program(), gss_destroy_cred(), or rpc_clnt_test_and_add_xprt() can wait forever. Signed-off-by: Chuck Lever --- net/sunrpc/clnt.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index ca2000d8cf64..d34737a8a68a 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -2694,6 +2694,18 @@ static const struct rpc_procinfo rpcproc_null = { .p_decode = rpcproc_decode_null, }; +static void +rpc_null_call_prepare(struct rpc_task *task, void *data) +{ + task->tk_flags &= ~RPC_TASK_NO_RETRANS_TIMEOUT; + rpc_call_start(task); +} + +static const struct rpc_call_ops rpc_null_ops = { + .rpc_call_prepare = rpc_null_call_prepare, + .rpc_call_done = rpc_default_callback, +}; + static struct rpc_task *rpc_call_null_helper(struct rpc_clnt *clnt, struct rpc_xprt *xprt, struct rpc_cred *cred, int flags, @@ -2707,7 +2719,7 @@ struct rpc_task *rpc_call_null_helper(struct rpc_clnt *clnt, .rpc_xprt = xprt, .rpc_message = &msg, .rpc_op_cred = cred, - .callback_ops = (ops != NULL) ? ops : &rpc_default_ops, + .callback_ops = ops ?: &rpc_null_ops, .callback_data = data, .flags = flags | RPC_TASK_SOFT | RPC_TASK_SOFTCONN | RPC_TASK_NULLCREDS, @@ -2758,6 +2770,7 @@ static void rpc_cb_add_xprt_release(void *calldata) } static const struct rpc_call_ops rpc_cb_add_xprt_call_ops = { + .rpc_call_prepare = rpc_null_call_prepare, .rpc_call_done = rpc_cb_add_xprt_done, .rpc_release = rpc_cb_add_xprt_release, };