net/smc/smc_clc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  Shared Memory Communications over RDMA (SMC-R) and RoCE
  *
  *  CLC (connection layer control) handshake over initial TCP socket to
  *  prepare for RDMA traffic
  *
  *  Copyright IBM Corp. 2016, 2018
  *
  *  Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
  */

 #include <linux/in.h>
 #include <linux/inetdevice.h>
 #include <linux/if_ether.h>
 #include <linux/sched/signal.h>

 #include <net/addrconf.h>
 #include <net/sock.h>
 #include <net/tcp.h>

 #include "smc.h"
 #include "smc_core.h"
 #include "smc_clc.h"
 #include "smc_ib.h"
 #include "smc_ism.h"

 #define SMCR_CLC_ACCEPT_CONFIRM_LEN 68
 #define SMCD_CLC_ACCEPT_CONFIRM_LEN 48

 /* eye catcher "SMCR" EBCDIC for CLC messages */
 static const char SMC_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xd9'};
 /* eye catcher "SMCD" EBCDIC for CLC messages */
 static const char SMCD_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xc4'};

 /* check if received message has a correct header length and contains valid
  * heading and trailing eyecatchers
  */
 static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm)
 {
 	struct smc_clc_msg_proposal_prefix *pclc_prfx;
 	struct smc_clc_msg_accept_confirm *clc;
 	struct smc_clc_msg_proposal *pclc;
 	struct smc_clc_msg_decline *dclc;
 	struct smc_clc_msg_trail *trl;

 	if (memcmp(clcm->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER)) &&
 	    memcmp(clcm->eyecatcher, SMCD_EYECATCHER, sizeof(SMCD_EYECATCHER)))
 		return false;
 	switch (clcm->type) {
 	case SMC_CLC_PROPOSAL:
 		if (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
 		    clcm->path != SMC_TYPE_B)
 			return false;
 		pclc = (struct smc_clc_msg_proposal *)clcm;
 		pclc_prfx = smc_clc_proposal_get_prefix(pclc);
 		if (ntohs(pclc->hdr.length) !=
 			sizeof(*pclc) + ntohs(pclc->iparea_offset) +
 			sizeof(*pclc_prfx) +
 			pclc_prfx->ipv6_prefixes_cnt *
 				sizeof(struct smc_clc_ipv6_prefix) +
 			sizeof(*trl))
 			return false;
 		trl = (struct smc_clc_msg_trail *)
 			((u8 *)pclc + ntohs(pclc->hdr.length) - sizeof(*trl));
 		break;
 	case SMC_CLC_ACCEPT:
 	case SMC_CLC_CONFIRM:
 		if (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D)
 			return false;
 		clc = (struct smc_clc_msg_accept_confirm *)clcm;
 		if ((clcm->path == SMC_TYPE_R &&
 		     ntohs(clc->hdr.length) != SMCR_CLC_ACCEPT_CONFIRM_LEN) ||
 		    (clcm->path == SMC_TYPE_D &&
 		     ntohs(clc->hdr.length) != SMCD_CLC_ACCEPT_CONFIRM_LEN))
 			return false;
 		trl = (struct smc_clc_msg_trail *)
 			((u8 *)clc + ntohs(clc->hdr.length) - sizeof(*trl));
 		break;
 	case SMC_CLC_DECLINE:
 		dclc = (struct smc_clc_msg_decline *)clcm;
 		if (ntohs(dclc->hdr.length) != sizeof(*dclc))
 			return false;
 		trl = &dclc->trl;
 		break;
 	default:
 		return false;
 	}
 	if (memcmp(trl->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER)) &&
 	    memcmp(trl->eyecatcher, SMCD_EYECATCHER, sizeof(SMCD_EYECATCHER)))
 		return false;
 	return true;
 }

 /* find ipv4 addr on device and get the prefix len, fill CLC proposal msg */
 static int smc_clc_prfx_set4_rcu(struct dst_entry *dst, __be32 ipv4,
 				 struct smc_clc_msg_proposal_prefix *prop)
 {
 	struct in_device *in_dev = __in_dev_get_rcu(dst->dev);
 	const struct in_ifaddr *ifa;

 	if (!in_dev)
 		return -ENODEV;

 	in_dev_for_each_ifa_rcu(ifa, in_dev) {
 		if (!inet_ifa_match(ipv4, ifa))
 			continue;
 		prop->prefix_len = inet_mask_len(ifa->ifa_mask);
 		prop->outgoing_subnet = ifa->ifa_address & ifa->ifa_mask;
 		/* prop->ipv6_prefixes_cnt = 0; already done by memset before */
 		return 0;
 	}
 	return -ENOENT;
 }

 /* fill CLC proposal msg with ipv6 prefixes from device */
 static int smc_clc_prfx_set6_rcu(struct dst_entry *dst,
 				 struct smc_clc_msg_proposal_prefix *prop,
 				 struct smc_clc_ipv6_prefix *ipv6_prfx)
 {
 #if IS_ENABLED(CONFIG_IPV6)
 	struct inet6_dev *in6_dev = __in6_dev_get(dst->dev);
 	struct inet6_ifaddr *ifa;
 	int cnt = 0;

 	if (!in6_dev)
 		return -ENODEV;
 	/* use a maximum of 8 IPv6 prefixes from device */
 	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
 		if (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)
 			continue;
 		ipv6_addr_prefix(&ipv6_prfx[cnt].prefix,
 				 &ifa->addr, ifa->prefix_len);
 		ipv6_prfx[cnt].prefix_len = ifa->prefix_len;
 		cnt++;
 		if (cnt == SMC_CLC_MAX_V6_PREFIX)
 			break;
 	}
 	prop->ipv6_prefixes_cnt = cnt;
 	if (cnt)
 		return 0;
 #endif
 	return -ENOENT;
 }

 /* retrieve and set prefixes in CLC proposal msg */
 static int smc_clc_prfx_set(struct socket *clcsock,
 			    struct smc_clc_msg_proposal_prefix *prop,
 			    struct smc_clc_ipv6_prefix *ipv6_prfx)
 {
 	struct dst_entry *dst = sk_dst_get(clcsock->sk);
 	struct sockaddr_storage addrs;
 	struct sockaddr_in6 *addr6;
 	struct sockaddr_in *addr;
 	int rc = -ENOENT;

 	memset(prop, 0, sizeof(*prop));
 	if (!dst) {
 		rc = -ENOTCONN;
 		goto out;
 	}
 	if (!dst->dev) {
 		rc = -ENODEV;
 		goto out_rel;
 	}
 	/* get address to which the internal TCP socket is bound */
 	kernel_getsockname(clcsock, (struct sockaddr *)&addrs);
 	/* analyze IP specific data of net_device belonging to TCP socket */
 	addr6 = (struct sockaddr_in6 *)&addrs;
 	rcu_read_lock();
 	if (addrs.ss_family == PF_INET) {
 		/* IPv4 */
 		addr = (struct sockaddr_in *)&addrs;
 		rc = smc_clc_prfx_set4_rcu(dst, addr->sin_addr.s_addr, prop);
 	} else if (ipv6_addr_v4mapped(&addr6->sin6_addr)) {
 		/* mapped IPv4 address - peer is IPv4 only */
 		rc = smc_clc_prfx_set4_rcu(dst, addr6->sin6_addr.s6_addr32[3],
 					   prop);
 	} else {
 		/* IPv6 */
 		rc = smc_clc_prfx_set6_rcu(dst, prop, ipv6_prfx);
 	}
 	rcu_read_unlock();
 out_rel:
 	dst_release(dst);
 out:
 	return rc;
 }

 /* match ipv4 addrs of dev against addr in CLC proposal */
 static int smc_clc_prfx_match4_rcu(struct net_device *dev,
 				   struct smc_clc_msg_proposal_prefix *prop)
 {
 	struct in_device *in_dev = __in_dev_get_rcu(dev);
 	const struct in_ifaddr *ifa;

 	if (!in_dev)
 		return -ENODEV;
 	in_dev_for_each_ifa_rcu(ifa, in_dev) {
 		if (prop->prefix_len == inet_mask_len(ifa->ifa_mask) &&
 		    inet_ifa_match(prop->outgoing_subnet, ifa))
 			return 0;
 	}

 	return -ENOENT;
 }

 /* match ipv6 addrs of dev against addrs in CLC proposal */
 static int smc_clc_prfx_match6_rcu(struct net_device *dev,
 				   struct smc_clc_msg_proposal_prefix *prop)
 {
 #if IS_ENABLED(CONFIG_IPV6)
 	struct inet6_dev *in6_dev = __in6_dev_get(dev);
 	struct smc_clc_ipv6_prefix *ipv6_prfx;
 	struct inet6_ifaddr *ifa;
 	int i, max;

 	if (!in6_dev)
 		return -ENODEV;
 	/* ipv6 prefix list starts behind smc_clc_msg_proposal_prefix */
 	ipv6_prfx = (struct smc_clc_ipv6_prefix *)((u8 *)prop + sizeof(*prop));
 	max = min_t(u8, prop->ipv6_prefixes_cnt, SMC_CLC_MAX_V6_PREFIX);
 	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
 		if (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)
 			continue;
 		for (i = 0; i < max; i++) {
 			if (ifa->prefix_len == ipv6_prfx[i].prefix_len &&
 			    ipv6_prefix_equal(&ifa->addr, &ipv6_prfx[i].prefix,
 					      ifa->prefix_len))
 				return 0;
 		}
 	}
 #endif
 	return -ENOENT;
 }

 /* check if proposed prefixes match one of our device prefixes */
 int smc_clc_prfx_match(struct socket *clcsock,
 		       struct smc_clc_msg_proposal_prefix *prop)
 {
 	struct dst_entry *dst = sk_dst_get(clcsock->sk);
 	int rc;

 	if (!dst) {
 		rc = -ENOTCONN;
 		goto out;
 	}
 	if (!dst->dev) {
 		rc = -ENODEV;
 		goto out_rel;
 	}
 	rcu_read_lock();
 	if (!prop->ipv6_prefixes_cnt)
 		rc = smc_clc_prfx_match4_rcu(dst->dev, prop);
 	else
 		rc = smc_clc_prfx_match6_rcu(dst->dev, prop);
 	rcu_read_unlock();
 out_rel:
 	dst_release(dst);
 out:
 	return rc;
 }

 /* Wait for data on the tcp-socket, analyze received data
  * Returns:
  * 0 if success and it was not a decline that we received.
  * SMC_CLC_DECL_REPLY if decline received for fallback w/o another decl send.
  * clcsock error, -EINTR, -ECONNRESET, -EPROTO otherwise.
  */
 int smc_clc_wait_msg(struct smc_sock *smc, void *buf, int buflen,
 		     u8 expected_type, unsigned long timeout)
 {
 	long rcvtimeo = smc->clcsock->sk->sk_rcvtimeo;
 	struct sock *clc_sk = smc->clcsock->sk;
 	struct smc_clc_msg_hdr *clcm = buf;
 	struct msghdr msg = {NULL, 0};
 	int reason_code = 0;
 	struct kvec vec = {buf, buflen};
 	int len, datlen;
 	int krflags;

 	/* peek the first few bytes to determine length of data to receive
 	 * so we don't consume any subsequent CLC message or payload data
 	 * in the TCP byte stream
 	 */
 	/*
 	 * Caller must make sure that buflen is no less than
 	 * sizeof(struct smc_clc_msg_hdr)
 	 */
 	krflags = MSG_PEEK | MSG_WAITALL;
 	clc_sk->sk_rcvtimeo = timeout;
 	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1,
 			sizeof(struct smc_clc_msg_hdr));
 	len = sock_recvmsg(smc->clcsock, &msg, krflags);
 	if (signal_pending(current)) {
 		reason_code = -EINTR;
 		clc_sk->sk_err = EINTR;
 		smc->sk.sk_err = EINTR;
 		goto out;
 	}
 	if (clc_sk->sk_err) {
 		reason_code = -clc_sk->sk_err;
 		if (clc_sk->sk_err == EAGAIN &&
 		    expected_type == SMC_CLC_DECLINE)
 			clc_sk->sk_err = 0; /* reset for fallback usage */
 		else
 			smc->sk.sk_err = clc_sk->sk_err;
 		goto out;
 	}
 	if (!len) { /* peer has performed orderly shutdown */
 		smc->sk.sk_err = ECONNRESET;
 		reason_code = -ECONNRESET;
 		goto out;
 	}
 	if (len < 0) {
 		if (len != -EAGAIN || expected_type != SMC_CLC_DECLINE)
 			smc->sk.sk_err = -len;
 		reason_code = len;
 		goto out;
 	}
 	datlen = ntohs(clcm->length);
 	if ((len < sizeof(struct smc_clc_msg_hdr)) ||
 	    (datlen > buflen) ||
 	    (clcm->version != SMC_CLC_V1) ||
 	    (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
 	     clcm->path != SMC_TYPE_B) ||
 	    ((clcm->type != SMC_CLC_DECLINE) &&
 	     (clcm->type != expected_type))) {
 		smc->sk.sk_err = EPROTO;
 		reason_code = -EPROTO;
 		goto out;
 	}

 	/* receive the complete CLC message */
 	memset(&msg, 0, sizeof(struct msghdr));
 	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, datlen);
 	krflags = MSG_WAITALL;
 	len = sock_recvmsg(smc->clcsock, &msg, krflags);
 	if (len < datlen || !smc_clc_msg_hdr_valid(clcm)) {
 		smc->sk.sk_err = EPROTO;
 		reason_code = -EPROTO;
 		goto out;
 	}
 	if (clcm->type == SMC_CLC_DECLINE) {
 		struct smc_clc_msg_decline *dclc;

 		dclc = (struct smc_clc_msg_decline *)clcm;
 		reason_code = SMC_CLC_DECL_PEERDECL;
 		smc->peer_diagnosis = ntohl(dclc->peer_diagnosis);
 		if (((struct smc_clc_msg_decline *)buf)->hdr.flag) {
 			smc->conn.lgr->sync_err = 1;
 			smc_lgr_terminate(smc->conn.lgr);
 		}
 	}

 out:
 	clc_sk->sk_rcvtimeo = rcvtimeo;
 	return reason_code;
 }

 /* send CLC DECLINE message across internal TCP socket */
 int smc_clc_send_decline(struct smc_sock *smc, u32 peer_diag_info)
 {
 	struct smc_clc_msg_decline dclc;
 	struct msghdr msg;
 	struct kvec vec;
 	int len;

 	memset(&dclc, 0, sizeof(dclc));
 	memcpy(dclc.hdr.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
 	dclc.hdr.type = SMC_CLC_DECLINE;
 	dclc.hdr.length = htons(sizeof(struct smc_clc_msg_decline));
 	dclc.hdr.version = SMC_CLC_V1;
 	dclc.hdr.flag = (peer_diag_info == SMC_CLC_DECL_SYNCERR) ? 1 : 0;
 	memcpy(dclc.id_for_peer, local_systemid, sizeof(local_systemid));
 	dclc.peer_diagnosis = htonl(peer_diag_info);
 	memcpy(dclc.trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));

 	memset(&msg, 0, sizeof(msg));
 	vec.iov_base = &dclc;
 	vec.iov_len = sizeof(struct smc_clc_msg_decline);
 	len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
 			     sizeof(struct smc_clc_msg_decline));
 	if (len < 0 || len < sizeof(struct smc_clc_msg_decline))
 		len = -EPROTO;
 	return len > 0 ? 0 : len;
 }

 /* send CLC PROPOSAL message across internal TCP socket */
 int smc_clc_send_proposal(struct smc_sock *smc, int smc_type,
 			  struct smc_init_info *ini)
 {
 	struct smc_clc_ipv6_prefix ipv6_prfx[SMC_CLC_MAX_V6_PREFIX];
 	struct smc_clc_msg_proposal_prefix pclc_prfx;
 	struct smc_clc_msg_smcd pclc_smcd;
 	struct smc_clc_msg_proposal pclc;
 	struct smc_clc_msg_trail trl;
 	int len, i, plen, rc;
 	int reason_code = 0;
 	struct kvec vec[5];
 	struct msghdr msg;

 	/* retrieve ip prefixes for CLC proposal msg */
 	rc = smc_clc_prfx_set(smc->clcsock, &pclc_prfx, ipv6_prfx);
 	if (rc)
 		return SMC_CLC_DECL_CNFERR; /* configuration error */

 	/* send SMC Proposal CLC message */
 	plen = sizeof(pclc) + sizeof(pclc_prfx) +
 	       (pclc_prfx.ipv6_prefixes_cnt * sizeof(ipv6_prfx[0])) +
 	       sizeof(trl);
 	memset(&pclc, 0, sizeof(pclc));
 	memcpy(pclc.hdr.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
 	pclc.hdr.type = SMC_CLC_PROPOSAL;
 	pclc.hdr.version = SMC_CLC_V1;		/* SMC version */
 	pclc.hdr.path = smc_type;
 	if (smc_type == SMC_TYPE_R || smc_type == SMC_TYPE_B) {
 		/* add SMC-R specifics */
 		memcpy(pclc.lcl.id_for_peer, local_systemid,
 		       sizeof(local_systemid));
 		memcpy(&pclc.lcl.gid, ini->ib_gid, SMC_GID_SIZE);
 		memcpy(&pclc.lcl.mac, &ini->ib_dev->mac[ini->ib_port - 1],
 		       ETH_ALEN);
 		pclc.iparea_offset = htons(0);
 	}
 	if (smc_type == SMC_TYPE_D || smc_type == SMC_TYPE_B) {
 		/* add SMC-D specifics */
 		memset(&pclc_smcd, 0, sizeof(pclc_smcd));
 		plen += sizeof(pclc_smcd);
 		pclc.iparea_offset = htons(SMC_CLC_PROPOSAL_MAX_OFFSET);
 		pclc_smcd.gid = ini->ism_dev->local_gid;
 	}
 	pclc.hdr.length = htons(plen);

 	memcpy(trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
 	memset(&msg, 0, sizeof(msg));
 	i = 0;
 	vec[i].iov_base = &pclc;
 	vec[i++].iov_len = sizeof(pclc);
 	if (smc_type == SMC_TYPE_D || smc_type == SMC_TYPE_B) {
 		vec[i].iov_base = &pclc_smcd;
 		vec[i++].iov_len = sizeof(pclc_smcd);
 	}
 	vec[i].iov_base = &pclc_prfx;
 	vec[i++].iov_len = sizeof(pclc_prfx);
 	if (pclc_prfx.ipv6_prefixes_cnt > 0) {
 		vec[i].iov_base = &ipv6_prfx[0];
 		vec[i++].iov_len = pclc_prfx.ipv6_prefixes_cnt *
 				   sizeof(ipv6_prfx[0]);
 	}
 	vec[i].iov_base = &trl;
 	vec[i++].iov_len = sizeof(trl);
 	/* due to the few bytes needed for clc-handshake this cannot block */
 	len = kernel_sendmsg(smc->clcsock, &msg, vec, i, plen);
 	if (len < 0) {
 		smc->sk.sk_err = smc->clcsock->sk->sk_err;
 		reason_code = -smc->sk.sk_err;
 	} else if (len < (int)sizeof(pclc)) {
 		reason_code = -ENETUNREACH;
 		smc->sk.sk_err = -reason_code;
 	}

 	return reason_code;
 }

 /* send CLC CONFIRM message across internal TCP socket */
 int smc_clc_send_confirm(struct smc_sock *smc)
 {
 	struct smc_connection *conn = &smc->conn;
 	struct smc_clc_msg_accept_confirm cclc;
 	struct smc_link *link;
 	int reason_code = 0;
 	struct msghdr msg;
 	struct kvec vec;
 	int len;

 	/* send SMC Confirm CLC msg */
 	memset(&cclc, 0, sizeof(cclc));
 	cclc.hdr.type = SMC_CLC_CONFIRM;
 	cclc.hdr.version = SMC_CLC_V1;		/* SMC version */
 	if (smc->conn.lgr->is_smcd) {
 		/* SMC-D specific settings */
 		memcpy(cclc.hdr.eyecatcher, SMCD_EYECATCHER,
 		       sizeof(SMCD_EYECATCHER));
 		cclc.hdr.path = SMC_TYPE_D;
 		cclc.hdr.length = htons(SMCD_CLC_ACCEPT_CONFIRM_LEN);
 		cclc.gid = conn->lgr->smcd->local_gid;
 		cclc.token = conn->rmb_desc->token;
 		cclc.dmbe_size = conn->rmbe_size_short;
 		cclc.dmbe_idx = 0;
 		memcpy(&cclc.linkid, conn->lgr->id, SMC_LGR_ID_SIZE);
 		memcpy(cclc.smcd_trl.eyecatcher, SMCD_EYECATCHER,
 		       sizeof(SMCD_EYECATCHER));
 	} else {
 		/* SMC-R specific settings */
 		link = &conn->lgr->lnk[SMC_SINGLE_LINK];
 		memcpy(cclc.hdr.eyecatcher, SMC_EYECATCHER,
 		       sizeof(SMC_EYECATCHER));
 		cclc.hdr.path = SMC_TYPE_R;
 		cclc.hdr.length = htons(SMCR_CLC_ACCEPT_CONFIRM_LEN);
 		memcpy(cclc.lcl.id_for_peer, local_systemid,
 		       sizeof(local_systemid));
 		memcpy(&cclc.lcl.gid, link->gid, SMC_GID_SIZE);
 		memcpy(&cclc.lcl.mac, &link->smcibdev->mac[link->ibport - 1],
 		       ETH_ALEN);
 		hton24(cclc.qpn, link->roce_qp->qp_num);
 		cclc.rmb_rkey =
 			htonl(conn->rmb_desc->mr_rx[SMC_SINGLE_LINK]->rkey);
 		cclc.rmbe_idx = 1; /* for now: 1 RMB = 1 RMBE */
 		cclc.rmbe_alert_token = htonl(conn->alert_token_local);
 		cclc.qp_mtu = min(link->path_mtu, link->peer_mtu);
 		cclc.rmbe_size = conn->rmbe_size_short;
 		cclc.rmb_dma_addr = cpu_to_be64((u64)sg_dma_address
 				(conn->rmb_desc->sgt[SMC_SINGLE_LINK].sgl));
 		hton24(cclc.psn, link->psn_initial);
 		memcpy(cclc.smcr_trl.eyecatcher, SMC_EYECATCHER,
 		       sizeof(SMC_EYECATCHER));
 	}

 	memset(&msg, 0, sizeof(msg));
 	vec.iov_base = &cclc;
 	vec.iov_len = ntohs(cclc.hdr.length);
 	len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
 			     ntohs(cclc.hdr.length));
 	if (len < ntohs(cclc.hdr.length)) {
 		if (len >= 0) {
 			reason_code = -ENETUNREACH;
 			smc->sk.sk_err = -reason_code;
 		} else {
 			smc->sk.sk_err = smc->clcsock->sk->sk_err;
 			reason_code = -smc->sk.sk_err;
 		}
 	}
 	return reason_code;
 }

 /* send CLC ACCEPT message across internal TCP socket */
 int smc_clc_send_accept(struct smc_sock *new_smc, int srv_first_contact)
 {
 	struct smc_connection *conn = &new_smc->conn;
 	struct smc_clc_msg_accept_confirm aclc;
 	struct smc_link *link;
 	struct msghdr msg;
 	struct kvec vec;
 	int len;

 	memset(&aclc, 0, sizeof(aclc));
 	aclc.hdr.type = SMC_CLC_ACCEPT;
 	aclc.hdr.version = SMC_CLC_V1;		/* SMC version */
 	if (srv_first_contact)
 		aclc.hdr.flag = 1;

 	if (new_smc->conn.lgr->is_smcd) {
 		/* SMC-D specific settings */
 		aclc.hdr.length = htons(SMCD_CLC_ACCEPT_CONFIRM_LEN);
 		memcpy(aclc.hdr.eyecatcher, SMCD_EYECATCHER,
 		       sizeof(SMCD_EYECATCHER));
 		aclc.hdr.path = SMC_TYPE_D;
 		aclc.gid = conn->lgr->smcd->local_gid;
 		aclc.token = conn->rmb_desc->token;
 		aclc.dmbe_size = conn->rmbe_size_short;
 		aclc.dmbe_idx = 0;
 		memcpy(&aclc.linkid, conn->lgr->id, SMC_LGR_ID_SIZE);
 		memcpy(aclc.smcd_trl.eyecatcher, SMCD_EYECATCHER,
 		       sizeof(SMCD_EYECATCHER));
 	} else {
 		/* SMC-R specific settings */
 		aclc.hdr.length = htons(SMCR_CLC_ACCEPT_CONFIRM_LEN);
 		memcpy(aclc.hdr.eyecatcher, SMC_EYECATCHER,
 		       sizeof(SMC_EYECATCHER));
 		aclc.hdr.path = SMC_TYPE_R;
 		link = &conn->lgr->lnk[SMC_SINGLE_LINK];
 		memcpy(aclc.lcl.id_for_peer, local_systemid,
 		       sizeof(local_systemid));
 		memcpy(&aclc.lcl.gid, link->gid, SMC_GID_SIZE);
 		memcpy(&aclc.lcl.mac, link->smcibdev->mac[link->ibport - 1],
 		       ETH_ALEN);
 		hton24(aclc.qpn, link->roce_qp->qp_num);
 		aclc.rmb_rkey =
 			htonl(conn->rmb_desc->mr_rx[SMC_SINGLE_LINK]->rkey);
 		aclc.rmbe_idx = 1;		/* as long as 1 RMB = 1 RMBE */
 		aclc.rmbe_alert_token = htonl(conn->alert_token_local);
 		aclc.qp_mtu = link->path_mtu;
 		aclc.rmbe_size = conn->rmbe_size_short,
 		aclc.rmb_dma_addr = cpu_to_be64((u64)sg_dma_address
 				(conn->rmb_desc->sgt[SMC_SINGLE_LINK].sgl));
 		hton24(aclc.psn, link->psn_initial);
 		memcpy(aclc.smcr_trl.eyecatcher, SMC_EYECATCHER,
 		       sizeof(SMC_EYECATCHER));
 	}

 	memset(&msg, 0, sizeof(msg));
 	vec.iov_base = &aclc;
 	vec.iov_len = ntohs(aclc.hdr.length);
 	len = kernel_sendmsg(new_smc->clcsock, &msg, &vec, 1,
 			     ntohs(aclc.hdr.length));
 	if (len < ntohs(aclc.hdr.length))
 		len = len >= 0 ? -EPROTO : -new_smc->clcsock->sk->sk_err;

 	return len > 0 ? 0 : len;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Shared Memory Communications over RDMA (SMC-R) and RoCE
	*
	* CLC (connection layer control) handshake over initial TCP socket to
	* prepare for RDMA traffic
	*
	* Copyright IBM Corp. 2016, 2018
	*
	* Author(s): Ursula Braun <ubraun@linux.vnet.ibm.com>
	*/

	#include <linux/in.h>
	#include <linux/inetdevice.h>
	#include <linux/if_ether.h>
	#include <linux/sched/signal.h>

	#include <net/addrconf.h>
	#include <net/sock.h>
	#include <net/tcp.h>

	#include "smc.h"
	#include "smc_core.h"
	#include "smc_clc.h"
	#include "smc_ib.h"
	#include "smc_ism.h"

	#define SMCR_CLC_ACCEPT_CONFIRM_LEN 68
	#define SMCD_CLC_ACCEPT_CONFIRM_LEN 48

	/* eye catcher "SMCR" EBCDIC for CLC messages */
	static const char SMC_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xd9'};
	/* eye catcher "SMCD" EBCDIC for CLC messages */
	static const char SMCD_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xc4'};

	/* check if received message has a correct header length and contains valid
	* heading and trailing eyecatchers
	*/
	static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm)
	{
	struct smc_clc_msg_proposal_prefix *pclc_prfx;
	struct smc_clc_msg_accept_confirm *clc;
	struct smc_clc_msg_proposal *pclc;
	struct smc_clc_msg_decline *dclc;
	struct smc_clc_msg_trail *trl;

	if (memcmp(clcm->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER)) &&
	memcmp(clcm->eyecatcher, SMCD_EYECATCHER, sizeof(SMCD_EYECATCHER)))
	return false;
	switch (clcm->type) {
	case SMC_CLC_PROPOSAL:
	if (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
	clcm->path != SMC_TYPE_B)
	return false;
	pclc = (struct smc_clc_msg_proposal *)clcm;
	pclc_prfx = smc_clc_proposal_get_prefix(pclc);
	if (ntohs(pclc->hdr.length) !=
	sizeof(*pclc) + ntohs(pclc->iparea_offset) +
	sizeof(*pclc_prfx) +
	pclc_prfx->ipv6_prefixes_cnt *
	sizeof(struct smc_clc_ipv6_prefix) +
	sizeof(*trl))
	return false;
	trl = (struct smc_clc_msg_trail *)
	((u8 )pclc + ntohs(pclc->hdr.length) - sizeof(trl));
	break;
	case SMC_CLC_ACCEPT:
	case SMC_CLC_CONFIRM:
	if (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D)
	return false;
	clc = (struct smc_clc_msg_accept_confirm *)clcm;
	if ((clcm->path == SMC_TYPE_R &&
	ntohs(clc->hdr.length) != SMCR_CLC_ACCEPT_CONFIRM_LEN) \|\|
	(clcm->path == SMC_TYPE_D &&
	ntohs(clc->hdr.length) != SMCD_CLC_ACCEPT_CONFIRM_LEN))
	return false;
	trl = (struct smc_clc_msg_trail *)
	((u8 )clc + ntohs(clc->hdr.length) - sizeof(trl));
	break;
	case SMC_CLC_DECLINE:
	dclc = (struct smc_clc_msg_decline *)clcm;
	if (ntohs(dclc->hdr.length) != sizeof(*dclc))
	return false;
	trl = &dclc->trl;
	break;
	default:
	return false;
	}
	if (memcmp(trl->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER)) &&
	memcmp(trl->eyecatcher, SMCD_EYECATCHER, sizeof(SMCD_EYECATCHER)))
	return false;
	return true;
	}

	/* find ipv4 addr on device and get the prefix len, fill CLC proposal msg */
	static int smc_clc_prfx_set4_rcu(struct dst_entry *dst, __be32 ipv4,
	struct smc_clc_msg_proposal_prefix *prop)
	{
	struct in_device *in_dev = __in_dev_get_rcu(dst->dev);
	const struct in_ifaddr *ifa;

	if (!in_dev)
	return -ENODEV;

	in_dev_for_each_ifa_rcu(ifa, in_dev) {
	if (!inet_ifa_match(ipv4, ifa))
	continue;
	prop->prefix_len = inet_mask_len(ifa->ifa_mask);
	prop->outgoing_subnet = ifa->ifa_address & ifa->ifa_mask;
	/* prop->ipv6_prefixes_cnt = 0; already done by memset before */
	return 0;
	}
	return -ENOENT;
	}

	/* fill CLC proposal msg with ipv6 prefixes from device */
	static int smc_clc_prfx_set6_rcu(struct dst_entry *dst,
	struct smc_clc_msg_proposal_prefix *prop,
	struct smc_clc_ipv6_prefix *ipv6_prfx)
	{
	#if IS_ENABLED(CONFIG_IPV6)
	struct inet6_dev *in6_dev = __in6_dev_get(dst->dev);
	struct inet6_ifaddr *ifa;
	int cnt = 0;

	if (!in6_dev)
	return -ENODEV;
	/* use a maximum of 8 IPv6 prefixes from device */
	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
	if (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)
	continue;
	ipv6_addr_prefix(&ipv6_prfx[cnt].prefix,
	&ifa->addr, ifa->prefix_len);
	ipv6_prfx[cnt].prefix_len = ifa->prefix_len;
	cnt++;
	if (cnt == SMC_CLC_MAX_V6_PREFIX)
	break;
	}
	prop->ipv6_prefixes_cnt = cnt;
	if (cnt)
	return 0;
	#endif
	return -ENOENT;
	}

	/* retrieve and set prefixes in CLC proposal msg */
	static int smc_clc_prfx_set(struct socket *clcsock,
	struct smc_clc_msg_proposal_prefix *prop,
	struct smc_clc_ipv6_prefix *ipv6_prfx)
	{
	struct dst_entry *dst = sk_dst_get(clcsock->sk);
	struct sockaddr_storage addrs;
	struct sockaddr_in6 *addr6;
	struct sockaddr_in *addr;
	int rc = -ENOENT;

	memset(prop, 0, sizeof(*prop));
	if (!dst) {
	rc = -ENOTCONN;
	goto out;
	}
	if (!dst->dev) {
	rc = -ENODEV;
	goto out_rel;
	}
	/* get address to which the internal TCP socket is bound */
	kernel_getsockname(clcsock, (struct sockaddr *)&addrs);
	/* analyze IP specific data of net_device belonging to TCP socket */
	addr6 = (struct sockaddr_in6 *)&addrs;
	rcu_read_lock();
	if (addrs.ss_family == PF_INET) {
	/* IPv4 */
	addr = (struct sockaddr_in *)&addrs;
	rc = smc_clc_prfx_set4_rcu(dst, addr->sin_addr.s_addr, prop);
	} else if (ipv6_addr_v4mapped(&addr6->sin6_addr)) {
	/* mapped IPv4 address - peer is IPv4 only */
	rc = smc_clc_prfx_set4_rcu(dst, addr6->sin6_addr.s6_addr32[3],
	prop);
	} else {
	/* IPv6 */
	rc = smc_clc_prfx_set6_rcu(dst, prop, ipv6_prfx);
	}
	rcu_read_unlock();
	out_rel:
	dst_release(dst);
	out:
	return rc;
	}

	/* match ipv4 addrs of dev against addr in CLC proposal */
	static int smc_clc_prfx_match4_rcu(struct net_device *dev,
	struct smc_clc_msg_proposal_prefix *prop)
	{
	struct in_device *in_dev = __in_dev_get_rcu(dev);
	const struct in_ifaddr *ifa;

	if (!in_dev)
	return -ENODEV;
	in_dev_for_each_ifa_rcu(ifa, in_dev) {
	if (prop->prefix_len == inet_mask_len(ifa->ifa_mask) &&
	inet_ifa_match(prop->outgoing_subnet, ifa))
	return 0;
	}

	return -ENOENT;
	}

	/* match ipv6 addrs of dev against addrs in CLC proposal */
	static int smc_clc_prfx_match6_rcu(struct net_device *dev,
	struct smc_clc_msg_proposal_prefix *prop)
	{
	#if IS_ENABLED(CONFIG_IPV6)
	struct inet6_dev *in6_dev = __in6_dev_get(dev);
	struct smc_clc_ipv6_prefix *ipv6_prfx;
	struct inet6_ifaddr *ifa;
	int i, max;

	if (!in6_dev)
	return -ENODEV;
	/* ipv6 prefix list starts behind smc_clc_msg_proposal_prefix */
	ipv6_prfx = (struct smc_clc_ipv6_prefix )((u8 )prop + sizeof(*prop));
	max = min_t(u8, prop->ipv6_prefixes_cnt, SMC_CLC_MAX_V6_PREFIX);
	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
	if (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)
	continue;
	for (i = 0; i < max; i++) {
	if (ifa->prefix_len == ipv6_prfx[i].prefix_len &&
	ipv6_prefix_equal(&ifa->addr, &ipv6_prfx[i].prefix,
	ifa->prefix_len))
	return 0;
	}
	}
	#endif
	return -ENOENT;
	}

	/* check if proposed prefixes match one of our device prefixes */
	int smc_clc_prfx_match(struct socket *clcsock,
	struct smc_clc_msg_proposal_prefix *prop)
	{
	struct dst_entry *dst = sk_dst_get(clcsock->sk);
	int rc;

	if (!dst) {
	rc = -ENOTCONN;
	goto out;
	}
	if (!dst->dev) {
	rc = -ENODEV;
	goto out_rel;
	}
	rcu_read_lock();
	if (!prop->ipv6_prefixes_cnt)
	rc = smc_clc_prfx_match4_rcu(dst->dev, prop);
	else
	rc = smc_clc_prfx_match6_rcu(dst->dev, prop);
	rcu_read_unlock();
	out_rel:
	dst_release(dst);
	out:
	return rc;
	}

	/* Wait for data on the tcp-socket, analyze received data
	* Returns:
	* 0 if success and it was not a decline that we received.
	* SMC_CLC_DECL_REPLY if decline received for fallback w/o another decl send.
	* clcsock error, -EINTR, -ECONNRESET, -EPROTO otherwise.
	*/
	int smc_clc_wait_msg(struct smc_sock smc, void buf, int buflen,
	u8 expected_type, unsigned long timeout)
	{
	long rcvtimeo = smc->clcsock->sk->sk_rcvtimeo;
	struct sock *clc_sk = smc->clcsock->sk;
	struct smc_clc_msg_hdr *clcm = buf;
	struct msghdr msg = {NULL, 0};
	int reason_code = 0;
	struct kvec vec = {buf, buflen};
	int len, datlen;
	int krflags;

	/* peek the first few bytes to determine length of data to receive
	* so we don't consume any subsequent CLC message or payload data
	* in the TCP byte stream
	*/
	/*
	* Caller must make sure that buflen is no less than
	* sizeof(struct smc_clc_msg_hdr)
	*/
	krflags = MSG_PEEK \| MSG_WAITALL;
	clc_sk->sk_rcvtimeo = timeout;
	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1,
	sizeof(struct smc_clc_msg_hdr));
	len = sock_recvmsg(smc->clcsock, &msg, krflags);
	if (signal_pending(current)) {
	reason_code = -EINTR;
	clc_sk->sk_err = EINTR;
	smc->sk.sk_err = EINTR;
	goto out;
	}
	if (clc_sk->sk_err) {
	reason_code = -clc_sk->sk_err;
	if (clc_sk->sk_err == EAGAIN &&
	expected_type == SMC_CLC_DECLINE)
	clc_sk->sk_err = 0; /* reset for fallback usage */
	else
	smc->sk.sk_err = clc_sk->sk_err;
	goto out;
	}
	if (!len) { /* peer has performed orderly shutdown */
	smc->sk.sk_err = ECONNRESET;
	reason_code = -ECONNRESET;
	goto out;
	}
	if (len < 0) {
	if (len != -EAGAIN \|\| expected_type != SMC_CLC_DECLINE)
	smc->sk.sk_err = -len;
	reason_code = len;
	goto out;
	}
	datlen = ntohs(clcm->length);
	if ((len < sizeof(struct smc_clc_msg_hdr)) \|\|
	(datlen > buflen) \|\|
	(clcm->version != SMC_CLC_V1) \|\|
	(clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
	clcm->path != SMC_TYPE_B) \|\|
	((clcm->type != SMC_CLC_DECLINE) &&
	(clcm->type != expected_type))) {
	smc->sk.sk_err = EPROTO;
	reason_code = -EPROTO;
	goto out;
	}

	/* receive the complete CLC message */
	memset(&msg, 0, sizeof(struct msghdr));
	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, datlen);
	krflags = MSG_WAITALL;
	len = sock_recvmsg(smc->clcsock, &msg, krflags);
	if (len < datlen \|\| !smc_clc_msg_hdr_valid(clcm)) {
	smc->sk.sk_err = EPROTO;
	reason_code = -EPROTO;
	goto out;
	}
	if (clcm->type == SMC_CLC_DECLINE) {
	struct smc_clc_msg_decline *dclc;

	dclc = (struct smc_clc_msg_decline *)clcm;
	reason_code = SMC_CLC_DECL_PEERDECL;
	smc->peer_diagnosis = ntohl(dclc->peer_diagnosis);
	if (((struct smc_clc_msg_decline *)buf)->hdr.flag) {
	smc->conn.lgr->sync_err = 1;
	smc_lgr_terminate(smc->conn.lgr);
	}
	}

	out:
	clc_sk->sk_rcvtimeo = rcvtimeo;
	return reason_code;
	}

	/* send CLC DECLINE message across internal TCP socket */
	int smc_clc_send_decline(struct smc_sock *smc, u32 peer_diag_info)
	{
	struct smc_clc_msg_decline dclc;
	struct msghdr msg;
	struct kvec vec;
	int len;

	memset(&dclc, 0, sizeof(dclc));
	memcpy(dclc.hdr.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
	dclc.hdr.type = SMC_CLC_DECLINE;
	dclc.hdr.length = htons(sizeof(struct smc_clc_msg_decline));
	dclc.hdr.version = SMC_CLC_V1;
	dclc.hdr.flag = (peer_diag_info == SMC_CLC_DECL_SYNCERR) ? 1 : 0;
	memcpy(dclc.id_for_peer, local_systemid, sizeof(local_systemid));
	dclc.peer_diagnosis = htonl(peer_diag_info);
	memcpy(dclc.trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));

	memset(&msg, 0, sizeof(msg));
	vec.iov_base = &dclc;
	vec.iov_len = sizeof(struct smc_clc_msg_decline);
	len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
	sizeof(struct smc_clc_msg_decline));
	if (len < 0 \|\| len < sizeof(struct smc_clc_msg_decline))
	len = -EPROTO;
	return len > 0 ? 0 : len;
	}

	/* send CLC PROPOSAL message across internal TCP socket */
	int smc_clc_send_proposal(struct smc_sock *smc, int smc_type,
	struct smc_init_info *ini)
	{
	struct smc_clc_ipv6_prefix ipv6_prfx[SMC_CLC_MAX_V6_PREFIX];
	struct smc_clc_msg_proposal_prefix pclc_prfx;
	struct smc_clc_msg_smcd pclc_smcd;
	struct smc_clc_msg_proposal pclc;
	struct smc_clc_msg_trail trl;
	int len, i, plen, rc;
	int reason_code = 0;
	struct kvec vec[5];
	struct msghdr msg;

	/* retrieve ip prefixes for CLC proposal msg */
	rc = smc_clc_prfx_set(smc->clcsock, &pclc_prfx, ipv6_prfx);
	if (rc)
	return SMC_CLC_DECL_CNFERR; /* configuration error */

	/* send SMC Proposal CLC message */
	plen = sizeof(pclc) + sizeof(pclc_prfx) +
	(pclc_prfx.ipv6_prefixes_cnt * sizeof(ipv6_prfx[0])) +
	sizeof(trl);
	memset(&pclc, 0, sizeof(pclc));
	memcpy(pclc.hdr.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
	pclc.hdr.type = SMC_CLC_PROPOSAL;
	pclc.hdr.version = SMC_CLC_V1; /* SMC version */
	pclc.hdr.path = smc_type;
	if (smc_type == SMC_TYPE_R \|\| smc_type == SMC_TYPE_B) {
	/* add SMC-R specifics */
	memcpy(pclc.lcl.id_for_peer, local_systemid,
	sizeof(local_systemid));
	memcpy(&pclc.lcl.gid, ini->ib_gid, SMC_GID_SIZE);
	memcpy(&pclc.lcl.mac, &ini->ib_dev->mac[ini->ib_port - 1],
	ETH_ALEN);
	pclc.iparea_offset = htons(0);
	}
	if (smc_type == SMC_TYPE_D \|\| smc_type == SMC_TYPE_B) {
	/* add SMC-D specifics */
	memset(&pclc_smcd, 0, sizeof(pclc_smcd));
	plen += sizeof(pclc_smcd);
	pclc.iparea_offset = htons(SMC_CLC_PROPOSAL_MAX_OFFSET);
	pclc_smcd.gid = ini->ism_dev->local_gid;
	}
	pclc.hdr.length = htons(plen);

	memcpy(trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
	memset(&msg, 0, sizeof(msg));
	i = 0;
	vec[i].iov_base = &pclc;
	vec[i++].iov_len = sizeof(pclc);
	if (smc_type == SMC_TYPE_D \|\| smc_type == SMC_TYPE_B) {
	vec[i].iov_base = &pclc_smcd;
	vec[i++].iov_len = sizeof(pclc_smcd);
	}
	vec[i].iov_base = &pclc_prfx;
	vec[i++].iov_len = sizeof(pclc_prfx);
	if (pclc_prfx.ipv6_prefixes_cnt > 0) {
	vec[i].iov_base = &ipv6_prfx[0];
	vec[i++].iov_len = pclc_prfx.ipv6_prefixes_cnt *
	sizeof(ipv6_prfx[0]);
	}
	vec[i].iov_base = &trl;
	vec[i++].iov_len = sizeof(trl);
	/* due to the few bytes needed for clc-handshake this cannot block */
	len = kernel_sendmsg(smc->clcsock, &msg, vec, i, plen);
	if (len < 0) {
	smc->sk.sk_err = smc->clcsock->sk->sk_err;
	reason_code = -smc->sk.sk_err;
	} else if (len < (int)sizeof(pclc)) {
	reason_code = -ENETUNREACH;
	smc->sk.sk_err = -reason_code;
	}

	return reason_code;
	}

	/* send CLC CONFIRM message across internal TCP socket */
	int smc_clc_send_confirm(struct smc_sock *smc)
	{
	struct smc_connection *conn = &smc->conn;
	struct smc_clc_msg_accept_confirm cclc;
	struct smc_link *link;
	int reason_code = 0;
	struct msghdr msg;
	struct kvec vec;
	int len;

	/* send SMC Confirm CLC msg */
	memset(&cclc, 0, sizeof(cclc));
	cclc.hdr.type = SMC_CLC_CONFIRM;
	cclc.hdr.version = SMC_CLC_V1; /* SMC version */
	if (smc->conn.lgr->is_smcd) {
	/* SMC-D specific settings */
	memcpy(cclc.hdr.eyecatcher, SMCD_EYECATCHER,
	sizeof(SMCD_EYECATCHER));
	cclc.hdr.path = SMC_TYPE_D;
	cclc.hdr.length = htons(SMCD_CLC_ACCEPT_CONFIRM_LEN);
	cclc.gid = conn->lgr->smcd->local_gid;
	cclc.token = conn->rmb_desc->token;
	cclc.dmbe_size = conn->rmbe_size_short;
	cclc.dmbe_idx = 0;
	memcpy(&cclc.linkid, conn->lgr->id, SMC_LGR_ID_SIZE);
	memcpy(cclc.smcd_trl.eyecatcher, SMCD_EYECATCHER,
	sizeof(SMCD_EYECATCHER));
	} else {
	/* SMC-R specific settings */
	link = &conn->lgr->lnk[SMC_SINGLE_LINK];
	memcpy(cclc.hdr.eyecatcher, SMC_EYECATCHER,
	sizeof(SMC_EYECATCHER));
	cclc.hdr.path = SMC_TYPE_R;
	cclc.hdr.length = htons(SMCR_CLC_ACCEPT_CONFIRM_LEN);
	memcpy(cclc.lcl.id_for_peer, local_systemid,
	sizeof(local_systemid));
	memcpy(&cclc.lcl.gid, link->gid, SMC_GID_SIZE);
	memcpy(&cclc.lcl.mac, &link->smcibdev->mac[link->ibport - 1],
	ETH_ALEN);
	hton24(cclc.qpn, link->roce_qp->qp_num);
	cclc.rmb_rkey =
	htonl(conn->rmb_desc->mr_rx[SMC_SINGLE_LINK]->rkey);
	cclc.rmbe_idx = 1; /* for now: 1 RMB = 1 RMBE */
	cclc.rmbe_alert_token = htonl(conn->alert_token_local);
	cclc.qp_mtu = min(link->path_mtu, link->peer_mtu);
	cclc.rmbe_size = conn->rmbe_size_short;
	cclc.rmb_dma_addr = cpu_to_be64((u64)sg_dma_address
	(conn->rmb_desc->sgt[SMC_SINGLE_LINK].sgl));
	hton24(cclc.psn, link->psn_initial);
	memcpy(cclc.smcr_trl.eyecatcher, SMC_EYECATCHER,
	sizeof(SMC_EYECATCHER));
	}

	memset(&msg, 0, sizeof(msg));
	vec.iov_base = &cclc;
	vec.iov_len = ntohs(cclc.hdr.length);
	len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
	ntohs(cclc.hdr.length));
	if (len < ntohs(cclc.hdr.length)) {
	if (len >= 0) {
	reason_code = -ENETUNREACH;
	smc->sk.sk_err = -reason_code;
	} else {
	smc->sk.sk_err = smc->clcsock->sk->sk_err;
	reason_code = -smc->sk.sk_err;
	}
	}
	return reason_code;
	}

	/* send CLC ACCEPT message across internal TCP socket */
	int smc_clc_send_accept(struct smc_sock *new_smc, int srv_first_contact)
	{
	struct smc_connection *conn = &new_smc->conn;
	struct smc_clc_msg_accept_confirm aclc;
	struct smc_link *link;
	struct msghdr msg;
	struct kvec vec;
	int len;

	memset(&aclc, 0, sizeof(aclc));
	aclc.hdr.type = SMC_CLC_ACCEPT;
	aclc.hdr.version = SMC_CLC_V1; /* SMC version */
	if (srv_first_contact)
	aclc.hdr.flag = 1;

	if (new_smc->conn.lgr->is_smcd) {
	/* SMC-D specific settings */
	aclc.hdr.length = htons(SMCD_CLC_ACCEPT_CONFIRM_LEN);
	memcpy(aclc.hdr.eyecatcher, SMCD_EYECATCHER,
	sizeof(SMCD_EYECATCHER));
	aclc.hdr.path = SMC_TYPE_D;
	aclc.gid = conn->lgr->smcd->local_gid;
	aclc.token = conn->rmb_desc->token;
	aclc.dmbe_size = conn->rmbe_size_short;
	aclc.dmbe_idx = 0;
	memcpy(&aclc.linkid, conn->lgr->id, SMC_LGR_ID_SIZE);
	memcpy(aclc.smcd_trl.eyecatcher, SMCD_EYECATCHER,
	sizeof(SMCD_EYECATCHER));
	} else {
	/* SMC-R specific settings */
	aclc.hdr.length = htons(SMCR_CLC_ACCEPT_CONFIRM_LEN);
	memcpy(aclc.hdr.eyecatcher, SMC_EYECATCHER,
	sizeof(SMC_EYECATCHER));
	aclc.hdr.path = SMC_TYPE_R;
	link = &conn->lgr->lnk[SMC_SINGLE_LINK];
	memcpy(aclc.lcl.id_for_peer, local_systemid,
	sizeof(local_systemid));
	memcpy(&aclc.lcl.gid, link->gid, SMC_GID_SIZE);
	memcpy(&aclc.lcl.mac, link->smcibdev->mac[link->ibport - 1],
	ETH_ALEN);
	hton24(aclc.qpn, link->roce_qp->qp_num);
	aclc.rmb_rkey =
	htonl(conn->rmb_desc->mr_rx[SMC_SINGLE_LINK]->rkey);
	aclc.rmbe_idx = 1; /* as long as 1 RMB = 1 RMBE */
	aclc.rmbe_alert_token = htonl(conn->alert_token_local);
	aclc.qp_mtu = link->path_mtu;
	aclc.rmbe_size = conn->rmbe_size_short,
	aclc.rmb_dma_addr = cpu_to_be64((u64)sg_dma_address
	(conn->rmb_desc->sgt[SMC_SINGLE_LINK].sgl));
	hton24(aclc.psn, link->psn_initial);
	memcpy(aclc.smcr_trl.eyecatcher, SMC_EYECATCHER,
	sizeof(SMC_EYECATCHER));
	}

	memset(&msg, 0, sizeof(msg));
	vec.iov_base = &aclc;
	vec.iov_len = ntohs(aclc.hdr.length);
	len = kernel_sendmsg(new_smc->clcsock, &msg, &vec, 1,
	ntohs(aclc.hdr.length));
	if (len < ntohs(aclc.hdr.length))
	len = len >= 0 ? -EPROTO : -new_smc->clcsock->sk->sk_err;

	return len > 0 ? 0 : len;
	}