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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 617AFC678D4 for ; Mon, 6 Mar 2023 08:40:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229749AbjCFIkX (ORCPT ); Mon, 6 Mar 2023 03:40:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229651AbjCFIkW (ORCPT ); Mon, 6 Mar 2023 03:40:22 -0500 Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E72B7AB9; Mon, 6 Mar 2023 00:40:21 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045176;MF=tonylu@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0VdCwLpQ_1678092018; Received: from localhost(mailfrom:tonylu@linux.alibaba.com fp:SMTPD_---0VdCwLpQ_1678092018) by smtp.aliyun-inc.com; Mon, 06 Mar 2023 16:40:18 +0800 Date: Mon, 6 Mar 2023 16:40:17 +0800 From: Tony Lu To: "D. Wythe" Cc: kgraul@linux.ibm.com, wenjia@linux.ibm.com, jaka@linux.ibm.com, kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH net] net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler() Message-ID: Reply-To: Tony Lu References: <1678073786-110013-1-git-send-email-alibuda@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1678073786-110013-1-git-send-email-alibuda@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Mon, Mar 06, 2023 at 11:36:26AM +0800, D. Wythe wrote: > From: "D. Wythe" > > When performing a stress test on SMC-R by rmmod mlx5_ib driver > during the wrk/nginx test, we found that there is a probability > of triggering a panic while terminating all link groups. > > This issue dues to the race between smc_smcr_terminate_all() > and smc_buf_create(). > > smc_smcr_terminate_all > > smc_buf_create > /* init */ > conn->sndbuf_desc = NULL; > ... > > __smc_lgr_terminate > smc_conn_kill > smc_close_abort > smc_cdc_get_slot_and_msg_send > > __softirqentry_text_start > smc_wr_tx_process_cqe > smc_cdc_tx_handler > READ(conn->sndbuf_desc->len); > /* panic dues to NULL sndbuf_desc */ > > conn->sndbuf_desc = xxx; > > This patch tries to fix the issue by always to check the sndbuf_desc > before send any cdc msg, to make sure that no null pointer is > seen during cqe processing. > > Fixes: 0b29ec643613 ("net/smc: immediate termination for SMCR link groups") > Signed-off-by: D. Wythe LGTM. Reviewed-by: Tony Lu > --- > net/smc/smc_cdc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c > index 53f63bf..2f0e2ee 100644 > --- a/net/smc/smc_cdc.c > +++ b/net/smc/smc_cdc.c > @@ -114,6 +114,9 @@ int smc_cdc_msg_send(struct smc_connection *conn, > union smc_host_cursor cfed; > int rc; > > + if (unlikely(!READ_ONCE(conn->sndbuf_desc))) > + return -EINVAL; > + > smc_cdc_add_pending_send(conn, pend); > > conn->tx_cdc_seq++; > -- > 1.8.3.1