From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ursula Braun Subject: [PATCH V2 net-next 3/3] smc: add SMC rendezvous protocol Date: Wed, 18 Oct 2017 16:30:00 +0200 Message-ID: <20171018143000.23884-4-ubraun@linux.vnet.ibm.com> References: <20171018143000.23884-1-ubraun@linux.vnet.ibm.com> Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, jwi@linux.vnet.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, raspl@linux.vnet.ibm.com, ubraun@linux.vnet.ibm.com To: davem@davemloft.net Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51484 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751108AbdJROaM (ORCPT ); Wed, 18 Oct 2017 10:30:12 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v9IETKUm044523 for ; Wed, 18 Oct 2017 10:30:11 -0400 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0b-001b2d01.pphosted.com with ESMTP id 2dp4ukhd2u-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 18 Oct 2017 10:30:11 -0400 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 18 Oct 2017 15:30:10 +0100 In-Reply-To: <20171018143000.23884-1-ubraun@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: The SMC protocol [1] uses a rendezvous protocol to negotiate SMC capability between peers. The current Linux implementation does not yet use this rendezvous protocol and, thus, is not compliant to RFC7609 and incompatible with other SMC implementations like in zOS. This patch adds support for the SMC rendezvous protocol. It uses a new TCP experimental option. With this option, SMC capabilities are exchanged between the peers during the TCP three way handshake. [1] SMC-R Informational RFC: http://www.rfc-editor.org/info/rfc7609 Signed-off-by: Ursula Braun --- net/smc/af_smc.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index 70f7640f5090..6451c5013e06 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -390,6 +390,12 @@ static int smc_connect_rdma(struct smc_sock *smc) int rc = 0; u8 ibport; + if (!tcp_sk(smc->clcsock->sk)->syn_smc) { + /* peer has not signalled SMC-capability */ + smc->use_fallback = true; + goto out_connected; + } + /* IPSec connections opt out of SMC-R optimizations */ if (using_ipsec(smc)) { reason_code = SMC_CLC_DECL_IPSEC; @@ -555,6 +561,7 @@ static int smc_connect(struct socket *sock, struct sockaddr *addr, } smc_copy_sock_settings_to_clc(smc); + tcp_sk(smc->clcsock->sk)->syn_smc = 1; rc = kernel_connect(smc->clcsock, addr, alen, flags); if (rc) goto out; @@ -759,6 +766,12 @@ static void smc_listen_work(struct work_struct *work) u8 prefix_len; u8 ibport; + /* check if peer is smc capable */ + if (!tcp_sk(newclcsock->sk)->syn_smc) { + new_smc->use_fallback = true; + goto out_connected; + } + /* do inband token exchange - *wait for and receive SMC Proposal CLC message */ @@ -967,6 +980,7 @@ static int smc_listen(struct socket *sock, int backlog) * them to the clc socket -- copy smc socket options to clc socket */ smc_copy_sock_settings_to_clc(smc); + tcp_sk(smc->clcsock->sk)->syn_smc = 1; rc = kernel_listen(smc->clcsock, backlog); if (rc) @@ -1409,6 +1423,7 @@ static int __init smc_init(void) goto out_sock; } + static_branch_enable(&tcp_have_smc); return 0; out_sock: @@ -1433,6 +1448,7 @@ static void __exit smc_exit(void) list_del_init(&lgr->list); smc_lgr_free(lgr); /* free link group */ } + static_branch_disable(&tcp_have_smc); smc_ib_unregister_client(); sock_unregister(PF_SMC); proto_unregister(&smc_proto); -- 2.13.5