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 216FBC636D4 for ; Wed, 15 Feb 2023 09:28:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233908AbjBOJ2b (ORCPT ); Wed, 15 Feb 2023 04:28:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234002AbjBOJ2N (ORCPT ); Wed, 15 Feb 2023 04:28:13 -0500 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6ED0C3756D; Wed, 15 Feb 2023 01:28:11 -0800 (PST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 31F9QHts030084; Wed, 15 Feb 2023 09:28:02 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding : mime-version; s=pp1; bh=KtrD5MzuKc+1zQ4PbqZJg2u9nWvwjF3DPSp+E8uKgzw=; b=Ota31XnjbdKJ+TogdU3X/8ne65t+zLWMNEJ8I18RpGydlpNcm26kAsO1THgPv+THrfMc 5GtmG5dXymkL9fKYNt6RwYKEUQRuhL0Yo31+ByMD97jFVDwdFSntba5XvC7Ox5P+pW/k UqMRP2le156ZB0jra7m8twX61IyTudp3uchfHKQr4RZ5MkCZJIETqQiNvoND7u680kMh qAzZ7VM6VbYJzTRzeq5IBR4SPVDh4xi2vF8XYHFEdCT5qRurJaT2YU0iBVugycS97b7f +R8jFMohyMhRLC8pLxQhutNxoS5TFMhDiA+qOdr+Lvtzbfp7Vlr4+xBCMbWEpvOL++xi Yg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3nrvrwr0yp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Feb 2023 09:28:02 +0000 Received: from m0098396.ppops.net (m0098396.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 31F9S14W005194; Wed, 15 Feb 2023 09:28:01 GMT Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3nrvrwr0yb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Feb 2023 09:28:01 +0000 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 31F7Y3Ap000883; Wed, 15 Feb 2023 09:28:00 GMT Received: from smtprelay01.wdc07v.mail.ibm.com ([9.208.129.119]) by ppma04dal.us.ibm.com (PPS) with ESMTPS id 3np2n7h391-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 15 Feb 2023 09:28:00 +0000 Received: from smtpav06.wdc07v.mail.ibm.com (smtpav06.wdc07v.mail.ibm.com [10.39.53.233]) by smtprelay01.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 31F9Rw4G36373128 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 15 Feb 2023 09:27:58 GMT Received: from smtpav06.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7F9025804E; Wed, 15 Feb 2023 09:27:58 +0000 (GMT) Received: from smtpav06.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E8DAD5803F; Wed, 15 Feb 2023 09:27:56 +0000 (GMT) Received: from [9.211.88.109] (unknown [9.211.88.109]) by smtpav06.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 15 Feb 2023 09:27:56 +0000 (GMT) Message-ID: Date: Wed, 15 Feb 2023 10:27:55 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH net] net/smc: fix application data exception To: "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: <1669450950-27681-1-git-send-email-alibuda@linux.alibaba.com> From: Wenjia Zhang In-Reply-To: <1669450950-27681-1-git-send-email-alibuda@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: XXq6rq6IZce_4k7pOrl_nQv-ib0G2ZVr X-Proofpoint-ORIG-GUID: N8dsmhw7uf8nBi2Py5czWTpiPtrMHxaX Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.170.22 definitions=2023-02-15_05,2023-02-14_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 suspectscore=0 bulkscore=0 clxscore=1015 mlxlogscore=999 adultscore=0 priorityscore=1501 lowpriorityscore=0 mlxscore=0 phishscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2302150077 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 26.11.22 09:22, D.Wythe wrote: > From: "D. Wythe" > > There is a certain probability that following > exceptions will occur in the wrk benchmark test: > > Running 10s test @ http://11.213.45.6:80 > 8 threads and 64 connections > Thread Stats Avg Stdev Max +/- Stdev > Latency 3.72ms 13.94ms 245.33ms 94.17% > Req/Sec 1.96k 713.67 5.41k 75.16% > 155262 requests in 10.10s, 23.10MB read > Non-2xx or 3xx responses: 3 > > We will find that the error is HTTP 400 error, which is a serious > exception in our test, which means the application data was > corrupted. > > Consider the following scenarios: > > CPU0 CPU1 > > buf_desc->used = 0; > cmpxchg(buf_desc->used, 0, 1) > deal_with(buf_desc) > > memset(buf_desc->cpu_addr,0); > > This will cause the data received by a victim connection to be cleared, > thus triggering an HTTP 400 error in the server. > > This patch exchange the order between clear used and memset, add > barrier to ensure memory consistency. > > Fixes: 1c5526968e27 ("net/smc: Clear memory when release and reuse buffer") > Signed-off-by: D. Wythe > --- > net/smc/smc_core.c | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c > index c305d8d..c19d4b7 100644 > --- a/net/smc/smc_core.c > +++ b/net/smc/smc_core.c > @@ -1120,8 +1120,9 @@ static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb, > > smc_buf_free(lgr, is_rmb, buf_desc); > } else { > - buf_desc->used = 0; > - memset(buf_desc->cpu_addr, 0, buf_desc->len); > + /* memzero_explicit provides potential memory barrier semantics */ > + memzero_explicit(buf_desc->cpu_addr, buf_desc->len); > + WRITE_ONCE(buf_desc->used, 0); > } > } > > @@ -1132,19 +1133,17 @@ static void smc_buf_unuse(struct smc_connection *conn, > if (!lgr->is_smcd && conn->sndbuf_desc->is_vm) { > smcr_buf_unuse(conn->sndbuf_desc, false, lgr); > } else { > - conn->sndbuf_desc->used = 0; > - memset(conn->sndbuf_desc->cpu_addr, 0, > - conn->sndbuf_desc->len); > + memzero_explicit(conn->sndbuf_desc->cpu_addr, conn->sndbuf_desc->len); > + WRITE_ONCE(conn->sndbuf_desc->used, 0); > } > } > if (conn->rmb_desc) { > if (!lgr->is_smcd) { > smcr_buf_unuse(conn->rmb_desc, true, lgr); > } else { > - conn->rmb_desc->used = 0; > - memset(conn->rmb_desc->cpu_addr, 0, > - conn->rmb_desc->len + > - sizeof(struct smcd_cdc_msg)); > + memzero_explicit(conn->rmb_desc->cpu_addr, > + conn->rmb_desc->len + sizeof(struct smcd_cdc_msg)); > + WRITE_ONCE(conn->rmb_desc->used, 0); > } > } > } Hi David, Thank you for remembering me again about this patch. I did forget to answer you, sorry! My consideration was if memzero_explicit() is necessary in this case. But sure, it makes sense, especiall when the dereferencing is in somewhere else. Thank you for the fix! Reviewed-by: Wenjia Zhang