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 5941BC64EC4 for ; Mon, 6 Mar 2023 21:06:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229578AbjCFVGc (ORCPT ); Mon, 6 Mar 2023 16:06:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229565AbjCFVG1 (ORCPT ); Mon, 6 Mar 2023 16:06:27 -0500 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B2FE3BDB7; Mon, 6 Mar 2023 13:06:20 -0800 (PST) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 326K42t6011040; Mon, 6 Mar 2023 21:06:14 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=X+l+D0wTEg1NK0XLIfd80zTd+g8fH2sBn/mflmRj/20=; b=B9HCWoJBBBU/K7rA2Jx3B6QUjvVXv/QuFq9gFEN8Tam1lmy/fgANGLLjb+x9geEPhPGh edcA6ccr0pqmR0MUmgzQydhyMYiIDmGbUjyGcq+ZYRLep4sR1WlE0HVmS3BL5AiDo0l6 gYZtmbKYjVHKnOS/vzJm/W6MKD0WzEsFJQYjJrNDuVSiXROXtXIy+P1xg370thaP34+V lLTNTq+8waD5WFASTvRHgmNUqaMFkSsx4V3n38nLLz9NFikUVjOurFR06lGqMOtjCbdU ycPHRPE1EUM8GZXIaNOsoLNJ4rGuHWpg2qGS8XyF+pN1oa76K+CqoFIvO4aQwRxFl32e YQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3p50n4fya7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Mar 2023 21:06:13 +0000 Received: from m0098417.ppops.net (m0098417.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 326KUQ4i002476; Mon, 6 Mar 2023 21:06:13 GMT Received: from ppma01wdc.us.ibm.com (fd.55.37a9.ip4.static.sl-reverse.com [169.55.85.253]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3p50n4fy9u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Mar 2023 21:06:13 +0000 Received: from pps.filterd (ppma01wdc.us.ibm.com [127.0.0.1]) by ppma01wdc.us.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 326JWCmT005009; Mon, 6 Mar 2023 21:06:12 GMT Received: from smtprelay02.dal12v.mail.ibm.com ([9.208.130.97]) by ppma01wdc.us.ibm.com (PPS) with ESMTPS id 3p41847a4e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Mar 2023 21:06:12 +0000 Received: from smtpav04.wdc07v.mail.ibm.com (smtpav04.wdc07v.mail.ibm.com [10.39.53.231]) by smtprelay02.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 326L6But46138092 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 6 Mar 2023 21:06:11 GMT Received: from smtpav04.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 387D058045; Mon, 6 Mar 2023 21:06:11 +0000 (GMT) Received: from smtpav04.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 767CA58054; Mon, 6 Mar 2023 21:06:09 +0000 (GMT) Received: from [9.163.94.4] (unknown [9.163.94.4]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 6 Mar 2023 21:06:09 +0000 (GMT) Message-ID: <76103587-435d-159d-98b7-0c4cbedaf62e@linux.ibm.com> Date: Mon, 6 Mar 2023 22:06:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH net] net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler() To: Alexander H Duyck , "D. Wythe" , kgraul@linux.ibm.com, jaka@linux.ibm.com Cc: kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org References: <1678073786-110013-1-git-send-email-alibuda@linux.alibaba.com> From: Wenjia Zhang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: zVbj8YPHySCY0WwmG-Xq2A6BNZSWLC2S X-Proofpoint-GUID: tgmKc7x-4CZTWDmm1R4mUUSjvp5iNrmF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-06_14,2023-03-06_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 mlxlogscore=999 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 impostorscore=0 suspectscore=0 lowpriorityscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2303060183 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 06.03.23 17:38, Alexander H Duyck wrote: > On Mon, 2023-03-06 at 11:36 +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 > > Looking at the code for __smc_buf_create it seems like you might have > more issues hiding in the code. From what I can tell smc_buf_get_slot > can only return a pointer or NULL but it is getting checked for being > being a PTR_ERR or IS_ERR in several spots that are likely all dead > code. > This smc_buf_get_slot() is used to get a reusable slot, which is originally assigned by smcr_new_buf_create() or smcd_new_buf_create() depending on the device being used. In smcr_new_buf_create()/smcd_new_buf_create(), the pointer values of the return codes are converted from integer values. >> --- >> 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; >> + > > This return value doesn't seem right to me. Rather than en EINVAL > should this be something like a ENOBUFS just to make it easier to debug > when this issue is encountered? I agree. > >> smc_cdc_add_pending_send(conn, pend); >> >> conn->tx_cdc_seq++; > >