Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1974 insertions, 0 deletions

diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
new file mode 100644
index 000000000..d5ee961ca
--- /dev/null
+++ b/net/smc/smc_llc.c
@@ -0,0 +1,1974 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  Link Layer Control (LLC)
+ *
+ *  Copyright IBM Corp. 2016
+ *
+ *  Author(s):  Klaus Wacker <Klaus.Wacker@de.ibm.com>
+ *              Ursula Braun <ubraun@linux.vnet.ibm.com>
+ */
+
+#include <net/tcp.h>
+#include <rdma/ib_verbs.h>
+
+#include "smc.h"
+#include "smc_core.h"
+#include "smc_clc.h"
+#include "smc_llc.h"
+#include "smc_pnet.h"
+
+#define SMC_LLC_DATA_LEN		40
+
+struct smc_llc_hdr {
+	struct smc_wr_rx_hdr common;
+	u8 length;	/* 44 */
+#if defined(__BIG_ENDIAN_BITFIELD)
+	u8 reserved:4,
+	   add_link_rej_rsn:4;
+#elif defined(__LITTLE_ENDIAN_BITFIELD)
+	u8 add_link_rej_rsn:4,
+	   reserved:4;
+#endif
+	u8 flags;
+};
+
+#define SMC_LLC_FLAG_NO_RMBE_EYEC	0x03
+
+struct smc_llc_msg_confirm_link {	/* type 0x01 */
+	struct smc_llc_hdr hd;
+	u8 sender_mac[ETH_ALEN];
+	u8 sender_gid[SMC_GID_SIZE];
+	u8 sender_qp_num[3];
+	u8 link_num;
+	u8 link_uid[SMC_LGR_ID_SIZE];
+	u8 max_links;
+	u8 reserved[9];
+};
+
+#define SMC_LLC_FLAG_ADD_LNK_REJ	0x40
+#define SMC_LLC_REJ_RSN_NO_ALT_PATH	1
+
+#define SMC_LLC_ADD_LNK_MAX_LINKS	2
+
+struct smc_llc_msg_add_link {		/* type 0x02 */
+	struct smc_llc_hdr hd;
+	u8 sender_mac[ETH_ALEN];
+	u8 reserved2[2];
+	u8 sender_gid[SMC_GID_SIZE];
+	u8 sender_qp_num[3];
+	u8 link_num;
+#if defined(__BIG_ENDIAN_BITFIELD)
+	u8 reserved3 : 4,
+	   qp_mtu   : 4;
+#elif defined(__LITTLE_ENDIAN_BITFIELD)
+	u8 qp_mtu   : 4,
+	   reserved3 : 4;
+#endif
+	u8 initial_psn[3];
+	u8 reserved[8];
+};
+
+struct smc_llc_msg_add_link_cont_rt {
+	__be32 rmb_key;
+	__be32 rmb_key_new;
+	__be64 rmb_vaddr_new;
+};
+
+#define SMC_LLC_RKEYS_PER_CONT_MSG	2
+
+struct smc_llc_msg_add_link_cont {	/* type 0x03 */
+	struct smc_llc_hdr hd;
+	u8 link_num;
+	u8 num_rkeys;
+	u8 reserved2[2];
+	struct smc_llc_msg_add_link_cont_rt rt[SMC_LLC_RKEYS_PER_CONT_MSG];
+	u8 reserved[4];
+} __packed;			/* format defined in RFC7609 */
+
+#define SMC_LLC_FLAG_DEL_LINK_ALL	0x40
+#define SMC_LLC_FLAG_DEL_LINK_ORDERLY	0x20
+
+struct smc_llc_msg_del_link {		/* type 0x04 */
+	struct smc_llc_hdr hd;
+	u8 link_num;
+	__be32 reason;
+	u8 reserved[35];
+} __packed;			/* format defined in RFC7609 */
+
+struct smc_llc_msg_test_link {		/* type 0x07 */
+	struct smc_llc_hdr hd;
+	u8 user_data[16];
+	u8 reserved[24];
+};
+
+struct smc_rmb_rtoken {
+	union {
+		u8 num_rkeys;	/* first rtoken byte of CONFIRM LINK msg */
+				/* is actually the num of rtokens, first */
+				/* rtoken is always for the current link */
+		u8 link_id;	/* link id of the rtoken */
+	};
+	__be32 rmb_key;
+	__be64 rmb_vaddr;
+} __packed;			/* format defined in RFC7609 */
+
+#define SMC_LLC_RKEYS_PER_MSG	3
+
+struct smc_llc_msg_confirm_rkey {	/* type 0x06 */
+	struct smc_llc_hdr hd;
+	struct smc_rmb_rtoken rtoken[SMC_LLC_RKEYS_PER_MSG];
+	u8 reserved;
+};
+
+#define SMC_LLC_DEL_RKEY_MAX	8
+#define SMC_LLC_FLAG_RKEY_RETRY	0x10
+#define SMC_LLC_FLAG_RKEY_NEG	0x20
+
+struct smc_llc_msg_delete_rkey {	/* type 0x09 */
+	struct smc_llc_hdr hd;
+	u8 num_rkeys;
+	u8 err_mask;
+	u8 reserved[2];
+	__be32 rkey[8];
+	u8 reserved2[4];
+};
+
+union smc_llc_msg {
+	struct smc_llc_msg_confirm_link confirm_link;
+	struct smc_llc_msg_add_link add_link;
+	struct smc_llc_msg_add_link_cont add_link_cont;
+	struct smc_llc_msg_del_link delete_link;
+
+	struct smc_llc_msg_confirm_rkey confirm_rkey;
+	struct smc_llc_msg_delete_rkey delete_rkey;
+
+	struct smc_llc_msg_test_link test_link;
+	struct {
+		struct smc_llc_hdr hdr;
+		u8 data[SMC_LLC_DATA_LEN];
+	} raw;
+};
+
+#define SMC_LLC_FLAG_RESP		0x80
+
+struct smc_llc_qentry {
+	struct list_head list;
+	struct smc_link *link;
+	union smc_llc_msg msg;
+};
+
+static void smc_llc_enqueue(struct smc_link *link, union smc_llc_msg *llc);
+
+struct smc_llc_qentry *smc_llc_flow_qentry_clr(struct smc_llc_flow *flow)
+{
+	struct smc_llc_qentry *qentry = flow->qentry;
+
+	flow->qentry = NULL;
+	return qentry;
+}
+
+void smc_llc_flow_qentry_del(struct smc_llc_flow *flow)
+{
+	struct smc_llc_qentry *qentry;
+
+	if (flow->qentry) {
+		qentry = flow->qentry;
+		flow->qentry = NULL;
+		kfree(qentry);
+	}
+}
+
+static inline void smc_llc_flow_qentry_set(struct smc_llc_flow *flow,
+					   struct smc_llc_qentry *qentry)
+{
+	flow->qentry = qentry;
+}
+
+static void smc_llc_flow_parallel(struct smc_link_group *lgr, u8 flow_type,
+				  struct smc_llc_qentry *qentry)
+{
+	u8 msg_type = qentry->msg.raw.hdr.common.type;
+
+	if ((msg_type == SMC_LLC_ADD_LINK || msg_type == SMC_LLC_DELETE_LINK) &&
+	    flow_type != msg_type && !lgr->delayed_event) {
+		lgr->delayed_event = qentry;
+		return;
+	}
+	/* drop parallel or already-in-progress llc requests */
+	if (flow_type != msg_type)
+		pr_warn_once("smc: SMC-R lg %*phN dropped parallel "
+			     "LLC msg: msg %d flow %d role %d\n",
+			     SMC_LGR_ID_SIZE, &lgr->id,
+			     qentry->msg.raw.hdr.common.type,
+			     flow_type, lgr->role);
+	kfree(qentry);
+}
+
+/* try to start a new llc flow, initiated by an incoming llc msg */
+static bool smc_llc_flow_start(struct smc_llc_flow *flow,
+			       struct smc_llc_qentry *qentry)
+{
+	struct smc_link_group *lgr = qentry->link->lgr;
+
+	spin_lock_bh(&lgr->llc_flow_lock);
+	if (flow->type) {
+		/* a flow is already active */
+		smc_llc_flow_parallel(lgr, flow->type, qentry);
+		spin_unlock_bh(&lgr->llc_flow_lock);
+		return false;
+	}
+	switch (qentry->msg.raw.hdr.common.type) {
+	case SMC_LLC_ADD_LINK:
+		flow->type = SMC_LLC_FLOW_ADD_LINK;
+		break;
+	case SMC_LLC_DELETE_LINK:
+		flow->type = SMC_LLC_FLOW_DEL_LINK;
+		break;
+	case SMC_LLC_CONFIRM_RKEY:
+	case SMC_LLC_DELETE_RKEY:
+		flow->type = SMC_LLC_FLOW_RKEY;
+		break;
+	default:
+		flow->type = SMC_LLC_FLOW_NONE;
+	}
+	smc_llc_flow_qentry_set(flow, qentry);
+	spin_unlock_bh(&lgr->llc_flow_lock);
+	return true;
+}
+
+/* start a new local llc flow, wait till current flow finished */
+int smc_llc_flow_initiate(struct smc_link_group *lgr,
+			  enum smc_llc_flowtype type)
+{
+	enum smc_llc_flowtype allowed_remote = SMC_LLC_FLOW_NONE;
+	int rc;
+
+	/* all flows except confirm_rkey and delete_rkey are exclusive,
+	 * confirm/delete rkey flows can run concurrently (local and remote)
+	 */
+	if (type == SMC_LLC_FLOW_RKEY)
+		allowed_remote = SMC_LLC_FLOW_RKEY;
+again:
+	if (list_empty(&lgr->list))
+		return -ENODEV;
+	spin_lock_bh(&lgr->llc_flow_lock);
+	if (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE &&
+	    (lgr->llc_flow_rmt.type == SMC_LLC_FLOW_NONE ||
+	     lgr->llc_flow_rmt.type == allowed_remote)) {
+		lgr->llc_flow_lcl.type = type;
+		spin_unlock_bh(&lgr->llc_flow_lock);
+		return 0;
+	}
+	spin_unlock_bh(&lgr->llc_flow_lock);
+	rc = wait_event_timeout(lgr->llc_flow_waiter, (list_empty(&lgr->list) ||
+				(lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE &&
+				 (lgr->llc_flow_rmt.type == SMC_LLC_FLOW_NONE ||
+				  lgr->llc_flow_rmt.type == allowed_remote))),
+				SMC_LLC_WAIT_TIME * 10);
+	if (!rc)
+		return -ETIMEDOUT;
+	goto again;
+}
+
+/* finish the current llc flow */
+void smc_llc_flow_stop(struct smc_link_group *lgr, struct smc_llc_flow *flow)
+{
+	spin_lock_bh(&lgr->llc_flow_lock);
+	memset(flow, 0, sizeof(*flow));
+	flow->type = SMC_LLC_FLOW_NONE;
+	spin_unlock_bh(&lgr->llc_flow_lock);
+	if (!list_empty(&lgr->list) && lgr->delayed_event &&
+	    flow == &lgr->llc_flow_lcl)
+		schedule_work(&lgr->llc_event_work);
+	else
+		wake_up(&lgr->llc_flow_waiter);
+}
+
+/* lnk is optional and used for early wakeup when link goes down, useful in
+ * cases where we wait for a response on the link after we sent a request
+ */
+struct smc_llc_qentry *smc_llc_wait(struct smc_link_group *lgr,
+				    struct smc_link *lnk,
+				    int time_out, u8 exp_msg)
+{
+	struct smc_llc_flow *flow = &lgr->llc_flow_lcl;
+	u8 rcv_msg;
+
+	wait_event_timeout(lgr->llc_msg_waiter,
+			   (flow->qentry ||
+			    (lnk && !smc_link_usable(lnk)) ||
+			    list_empty(&lgr->list)),
+			   time_out);
+	if (!flow->qentry ||
+	    (lnk && !smc_link_usable(lnk)) || list_empty(&lgr->list)) {
+		smc_llc_flow_qentry_del(flow);
+		goto out;
+	}
+	rcv_msg = flow->qentry->msg.raw.hdr.common.type;
+	if (exp_msg && rcv_msg != exp_msg) {
+		if (exp_msg == SMC_LLC_ADD_LINK &&
+		    rcv_msg == SMC_LLC_DELETE_LINK) {
+			/* flow_start will delay the unexpected msg */
+			smc_llc_flow_start(&lgr->llc_flow_lcl,
+					   smc_llc_flow_qentry_clr(flow));
+			return NULL;
+		}
+		pr_warn_once("smc: SMC-R lg %*phN dropped unexpected LLC msg: "
+			     "msg %d exp %d flow %d role %d flags %x\n",
+			     SMC_LGR_ID_SIZE, &lgr->id, rcv_msg, exp_msg,
+			     flow->type, lgr->role,
+			     flow->qentry->msg.raw.hdr.flags);
+		smc_llc_flow_qentry_del(flow);
+	}
+out:
+	return flow->qentry;
+}
+
+/********************************** send *************************************/
+
+struct smc_llc_tx_pend {
+};
+
+/* handler for send/transmission completion of an LLC msg */
+static void smc_llc_tx_handler(struct smc_wr_tx_pend_priv *pend,
+			       struct smc_link *link,
+			       enum ib_wc_status wc_status)
+{
+	/* future work: handle wc_status error for recovery and failover */
+}
+
+/**
+ * smc_llc_add_pending_send() - add LLC control message to pending WQE transmits
+ * @link: Pointer to SMC link used for sending LLC control message.
+ * @wr_buf: Out variable returning pointer to work request payload buffer.
+ * @pend: Out variable returning pointer to private pending WR tracking.
+ *	  It's the context the transmit complete handler will get.
+ *
+ * Reserves and pre-fills an entry for a pending work request send/tx.
+ * Used by mid-level smc_llc_send_msg() to prepare for later actual send/tx.
+ * Can sleep due to smc_get_ctrl_buf (if not in softirq context).
+ *
+ * Return: 0 on success, otherwise an error value.
+ */
+static int smc_llc_add_pending_send(struct smc_link *link,
+				    struct smc_wr_buf **wr_buf,
+				    struct smc_wr_tx_pend_priv **pend)
+{
+	int rc;
+
+	rc = smc_wr_tx_get_free_slot(link, smc_llc_tx_handler, wr_buf, NULL,
+				     pend);
+	if (rc < 0)
+		return rc;
+	BUILD_BUG_ON_MSG(
+		sizeof(union smc_llc_msg) > SMC_WR_BUF_SIZE,
+		"must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_llc_msg)");
+	BUILD_BUG_ON_MSG(
+		sizeof(union smc_llc_msg) != SMC_WR_TX_SIZE,
+		"must adapt SMC_WR_TX_SIZE to sizeof(struct smc_llc_msg); if not all smc_wr upper layer protocols use the same message size any more, must start to set link->wr_tx_sges[i].length on each individual smc_wr_tx_send()");
+	BUILD_BUG_ON_MSG(
+		sizeof(struct smc_llc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
+		"must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_llc_tx_pend)");
+	return 0;
+}
+
+/* high-level API to send LLC confirm link */
+int smc_llc_send_confirm_link(struct smc_link *link,
+			      enum smc_llc_reqresp reqresp)
+{
+	struct smc_llc_msg_confirm_link *confllc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	confllc = (struct smc_llc_msg_confirm_link *)wr_buf;
+	memset(confllc, 0, sizeof(*confllc));
+	confllc->hd.common.type = SMC_LLC_CONFIRM_LINK;
+	confllc->hd.length = sizeof(struct smc_llc_msg_confirm_link);
+	confllc->hd.flags |= SMC_LLC_FLAG_NO_RMBE_EYEC;
+	if (reqresp == SMC_LLC_RESP)
+		confllc->hd.flags |= SMC_LLC_FLAG_RESP;
+	memcpy(confllc->sender_mac, link->smcibdev->mac[link->ibport - 1],
+	       ETH_ALEN);
+	memcpy(confllc->sender_gid, link->gid, SMC_GID_SIZE);
+	hton24(confllc->sender_qp_num, link->roce_qp->qp_num);
+	confllc->link_num = link->link_id;
+	memcpy(confllc->link_uid, link->link_uid, SMC_LGR_ID_SIZE);
+	confllc->max_links = SMC_LLC_ADD_LNK_MAX_LINKS;
+	/* send llc message */
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/* send LLC confirm rkey request */
+static int smc_llc_send_confirm_rkey(struct smc_link *send_link,
+				     struct smc_buf_desc *rmb_desc)
+{
+	struct smc_llc_msg_confirm_rkey *rkeyllc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	struct smc_link *link;
+	int i, rc, rtok_ix;
+
+	if (!smc_wr_tx_link_hold(send_link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(send_link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	rkeyllc = (struct smc_llc_msg_confirm_rkey *)wr_buf;
+	memset(rkeyllc, 0, sizeof(*rkeyllc));
+	rkeyllc->hd.common.type = SMC_LLC_CONFIRM_RKEY;
+	rkeyllc->hd.length = sizeof(struct smc_llc_msg_confirm_rkey);
+
+	rtok_ix = 1;
+	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+		link = &send_link->lgr->lnk[i];
+		if (smc_link_active(link) && link != send_link) {
+			rkeyllc->rtoken[rtok_ix].link_id = link->link_id;
+			rkeyllc->rtoken[rtok_ix].rmb_key =
+				htonl(rmb_desc->mr_rx[link->link_idx]->rkey);
+			rkeyllc->rtoken[rtok_ix].rmb_vaddr = cpu_to_be64(
+				(u64)sg_dma_address(
+					rmb_desc->sgt[link->link_idx].sgl));
+			rtok_ix++;
+		}
+	}
+	/* rkey of send_link is in rtoken[0] */
+	rkeyllc->rtoken[0].num_rkeys = rtok_ix - 1;
+	rkeyllc->rtoken[0].rmb_key =
+		htonl(rmb_desc->mr_rx[send_link->link_idx]->rkey);
+	rkeyllc->rtoken[0].rmb_vaddr = cpu_to_be64(
+		(u64)sg_dma_address(rmb_desc->sgt[send_link->link_idx].sgl));
+	/* send llc message */
+	rc = smc_wr_tx_send(send_link, pend);
+put_out:
+	smc_wr_tx_link_put(send_link);
+	return rc;
+}
+
+/* send LLC delete rkey request */
+static int smc_llc_send_delete_rkey(struct smc_link *link,
+				    struct smc_buf_desc *rmb_desc)
+{
+	struct smc_llc_msg_delete_rkey *rkeyllc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	rkeyllc = (struct smc_llc_msg_delete_rkey *)wr_buf;
+	memset(rkeyllc, 0, sizeof(*rkeyllc));
+	rkeyllc->hd.common.type = SMC_LLC_DELETE_RKEY;
+	rkeyllc->hd.length = sizeof(struct smc_llc_msg_delete_rkey);
+	rkeyllc->num_rkeys = 1;
+	rkeyllc->rkey[0] = htonl(rmb_desc->mr_rx[link->link_idx]->rkey);
+	/* send llc message */
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/* send ADD LINK request or response */
+int smc_llc_send_add_link(struct smc_link *link, u8 mac[], u8 gid[],
+			  struct smc_link *link_new,
+			  enum smc_llc_reqresp reqresp)
+{
+	struct smc_llc_msg_add_link *addllc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	addllc = (struct smc_llc_msg_add_link *)wr_buf;
+
+	memset(addllc, 0, sizeof(*addllc));
+	addllc->hd.common.type = SMC_LLC_ADD_LINK;
+	addllc->hd.length = sizeof(struct smc_llc_msg_add_link);
+	if (reqresp == SMC_LLC_RESP)
+		addllc->hd.flags |= SMC_LLC_FLAG_RESP;
+	memcpy(addllc->sender_mac, mac, ETH_ALEN);
+	memcpy(addllc->sender_gid, gid, SMC_GID_SIZE);
+	if (link_new) {
+		addllc->link_num = link_new->link_id;
+		hton24(addllc->sender_qp_num, link_new->roce_qp->qp_num);
+		hton24(addllc->initial_psn, link_new->psn_initial);
+		if (reqresp == SMC_LLC_REQ)
+			addllc->qp_mtu = link_new->path_mtu;
+		else
+			addllc->qp_mtu = min(link_new->path_mtu,
+					     link_new->peer_mtu);
+	}
+	/* send llc message */
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/* send DELETE LINK request or response */
+int smc_llc_send_delete_link(struct smc_link *link, u8 link_del_id,
+			     enum smc_llc_reqresp reqresp, bool orderly,
+			     u32 reason)
+{
+	struct smc_llc_msg_del_link *delllc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	delllc = (struct smc_llc_msg_del_link *)wr_buf;
+
+	memset(delllc, 0, sizeof(*delllc));
+	delllc->hd.common.type = SMC_LLC_DELETE_LINK;
+	delllc->hd.length = sizeof(struct smc_llc_msg_del_link);
+	if (reqresp == SMC_LLC_RESP)
+		delllc->hd.flags |= SMC_LLC_FLAG_RESP;
+	if (orderly)
+		delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
+	if (link_del_id)
+		delllc->link_num = link_del_id;
+	else
+		delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ALL;
+	delllc->reason = htonl(reason);
+	/* send llc message */
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/* send LLC test link request */
+static int smc_llc_send_test_link(struct smc_link *link, u8 user_data[16])
+{
+	struct smc_llc_msg_test_link *testllc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	testllc = (struct smc_llc_msg_test_link *)wr_buf;
+	memset(testllc, 0, sizeof(*testllc));
+	testllc->hd.common.type = SMC_LLC_TEST_LINK;
+	testllc->hd.length = sizeof(struct smc_llc_msg_test_link);
+	memcpy(testllc->user_data, user_data, sizeof(testllc->user_data));
+	/* send llc message */
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/* schedule an llc send on link, may wait for buffers */
+static int smc_llc_send_message(struct smc_link *link, void *llcbuf)
+{
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	memcpy(wr_buf, llcbuf, sizeof(union smc_llc_msg));
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/* schedule an llc send on link, may wait for buffers,
+ * and wait for send completion notification.
+ * @return 0 on success
+ */
+static int smc_llc_send_message_wait(struct smc_link *link, void *llcbuf)
+{
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	int rc;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	memcpy(wr_buf, llcbuf, sizeof(union smc_llc_msg));
+	rc = smc_wr_tx_send_wait(link, pend, SMC_LLC_WAIT_TIME);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+/********************************* receive ***********************************/
+
+static int smc_llc_alloc_alt_link(struct smc_link_group *lgr,
+				  enum smc_lgr_type lgr_new_t)
+{
+	int i;
+
+	if (lgr->type == SMC_LGR_SYMMETRIC ||
+	    (lgr->type != SMC_LGR_SINGLE &&
+	     (lgr_new_t == SMC_LGR_ASYMMETRIC_LOCAL ||
+	      lgr_new_t == SMC_LGR_ASYMMETRIC_PEER)))
+		return -EMLINK;
+
+	if (lgr_new_t == SMC_LGR_ASYMMETRIC_LOCAL ||
+	    lgr_new_t == SMC_LGR_ASYMMETRIC_PEER) {
+		for (i = SMC_LINKS_PER_LGR_MAX - 1; i >= 0; i--)
+			if (lgr->lnk[i].state == SMC_LNK_UNUSED)
+				return i;
+	} else {
+		for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++)
+			if (lgr->lnk[i].state == SMC_LNK_UNUSED)
+				return i;
+	}
+	return -EMLINK;
+}
+
+/* return first buffer from any of the next buf lists */
+static struct smc_buf_desc *_smc_llc_get_next_rmb(struct smc_link_group *lgr,
+						  int *buf_lst)
+{
+	struct smc_buf_desc *buf_pos;
+
+	while (*buf_lst < SMC_RMBE_SIZES) {
+		buf_pos = list_first_entry_or_null(&lgr->rmbs[*buf_lst],
+						   struct smc_buf_desc, list);
+		if (buf_pos)
+			return buf_pos;
+		(*buf_lst)++;
+	}
+	return NULL;
+}
+
+/* return next rmb from buffer lists */
+static struct smc_buf_desc *smc_llc_get_next_rmb(struct smc_link_group *lgr,
+						 int *buf_lst,
+						 struct smc_buf_desc *buf_pos)
+{
+	struct smc_buf_desc *buf_next;
+
+	if (!buf_pos || list_is_last(&buf_pos->list, &lgr->rmbs[*buf_lst])) {
+		(*buf_lst)++;
+		return _smc_llc_get_next_rmb(lgr, buf_lst);
+	}
+	buf_next = list_next_entry(buf_pos, list);
+	return buf_next;
+}
+
+static struct smc_buf_desc *smc_llc_get_first_rmb(struct smc_link_group *lgr,
+						  int *buf_lst)
+{
+	*buf_lst = 0;
+	return smc_llc_get_next_rmb(lgr, buf_lst, NULL);
+}
+
+/* send one add_link_continue msg */
+static int smc_llc_add_link_cont(struct smc_link *link,
+				 struct smc_link *link_new, u8 *num_rkeys_todo,
+				 int *buf_lst, struct smc_buf_desc **buf_pos)
+{
+	struct smc_llc_msg_add_link_cont *addc_llc;
+	struct smc_link_group *lgr = link->lgr;
+	int prim_lnk_idx, lnk_idx, i, rc;
+	struct smc_wr_tx_pend_priv *pend;
+	struct smc_wr_buf *wr_buf;
+	struct smc_buf_desc *rmb;
+	u8 n;
+
+	if (!smc_wr_tx_link_hold(link))
+		return -ENOLINK;
+	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+	if (rc)
+		goto put_out;
+	addc_llc = (struct smc_llc_msg_add_link_cont *)wr_buf;
+	memset(addc_llc, 0, sizeof(*addc_llc));
+
+	prim_lnk_idx = link->link_idx;
+	lnk_idx = link_new->link_idx;
+	addc_llc->link_num = link_new->link_id;
+	addc_llc->num_rkeys = *num_rkeys_todo;
+	n = *num_rkeys_todo;
+	for (i = 0; i < min_t(u8, n, SMC_LLC_RKEYS_PER_CONT_MSG); i++) {
+		while (*buf_pos && !(*buf_pos)->used)
+			*buf_pos = smc_llc_get_next_rmb(lgr, buf_lst, *buf_pos);
+		if (!*buf_pos) {
+			addc_llc->num_rkeys = addc_llc->num_rkeys -
+					      *num_rkeys_todo;
+			*num_rkeys_todo = 0;
+			break;
+		}
+		rmb = *buf_pos;
+
+		addc_llc->rt[i].rmb_key = htonl(rmb->mr_rx[prim_lnk_idx]->rkey);
+		addc_llc->rt[i].rmb_key_new = htonl(rmb->mr_rx[lnk_idx]->rkey);
+		addc_llc->rt[i].rmb_vaddr_new =
+			cpu_to_be64((u64)sg_dma_address(rmb->sgt[lnk_idx].sgl));
+
+		(*num_rkeys_todo)--;
+		*buf_pos = smc_llc_get_next_rmb(lgr, buf_lst, *buf_pos);
+	}
+	addc_llc->hd.common.type = SMC_LLC_ADD_LINK_CONT;
+	addc_llc->hd.length = sizeof(struct smc_llc_msg_add_link_cont);
+	if (lgr->role == SMC_CLNT)
+		addc_llc->hd.flags |= SMC_LLC_FLAG_RESP;
+	rc = smc_wr_tx_send(link, pend);
+put_out:
+	smc_wr_tx_link_put(link);
+	return rc;
+}
+
+static int smc_llc_cli_rkey_exchange(struct smc_link *link,
+				     struct smc_link *link_new)
+{
+	struct smc_llc_msg_add_link_cont *addc_llc;
+	struct smc_link_group *lgr = link->lgr;
+	u8 max, num_rkeys_send, num_rkeys_recv;
+	struct smc_llc_qentry *qentry;
+	struct smc_buf_desc *buf_pos;
+	int buf_lst;
+	int rc = 0;
+	int i;
+
+	mutex_lock(&lgr->rmbs_lock);
+	num_rkeys_send = lgr->conns_num;
+	buf_pos = smc_llc_get_first_rmb(lgr, &buf_lst);
+	do {
+		qentry = smc_llc_wait(lgr, NULL, SMC_LLC_WAIT_TIME,
+				      SMC_LLC_ADD_LINK_CONT);
+		if (!qentry) {
+			rc = -ETIMEDOUT;
+			break;
+		}
+		addc_llc = &qentry->msg.add_link_cont;
+		num_rkeys_recv = addc_llc->num_rkeys;
+		max = min_t(u8, num_rkeys_recv, SMC_LLC_RKEYS_PER_CONT_MSG);
+		for (i = 0; i < max; i++) {
+			smc_rtoken_set(lgr, link->link_idx, link_new->link_idx,
+				       addc_llc->rt[i].rmb_key,
+				       addc_llc->rt[i].rmb_vaddr_new,
+				       addc_llc->rt[i].rmb_key_new);
+			num_rkeys_recv--;
+		}
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		rc = smc_llc_add_link_cont(link, link_new, &num_rkeys_send,
+					   &buf_lst, &buf_pos);
+		if (rc)
+			break;
+	} while (num_rkeys_send || num_rkeys_recv);
+
+	mutex_unlock(&lgr->rmbs_lock);
+	return rc;
+}
+
+/* prepare and send an add link reject response */
+static int smc_llc_cli_add_link_reject(struct smc_llc_qentry *qentry)
+{
+	qentry->msg.raw.hdr.flags |= SMC_LLC_FLAG_RESP;
+	qentry->msg.raw.hdr.flags |= SMC_LLC_FLAG_ADD_LNK_REJ;
+	qentry->msg.raw.hdr.add_link_rej_rsn = SMC_LLC_REJ_RSN_NO_ALT_PATH;
+	return smc_llc_send_message(qentry->link, &qentry->msg);
+}
+
+static int smc_llc_cli_conf_link(struct smc_link *link,
+				 struct smc_init_info *ini,
+				 struct smc_link *link_new,
+				 enum smc_lgr_type lgr_new_t)
+{
+	struct smc_link_group *lgr = link->lgr;
+	struct smc_llc_qentry *qentry = NULL;
+	int rc = 0;
+
+	/* receive CONFIRM LINK request over RoCE fabric */
+	qentry = smc_llc_wait(lgr, NULL, SMC_LLC_WAIT_FIRST_TIME, 0);
+	if (!qentry) {
+		rc = smc_llc_send_delete_link(link, link_new->link_id,
+					      SMC_LLC_REQ, false,
+					      SMC_LLC_DEL_LOST_PATH);
+		return -ENOLINK;
+	}
+	if (qentry->msg.raw.hdr.common.type != SMC_LLC_CONFIRM_LINK) {
+		/* received DELETE_LINK instead */
+		qentry->msg.raw.hdr.flags |= SMC_LLC_FLAG_RESP;
+		smc_llc_send_message(link, &qentry->msg);
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		return -ENOLINK;
+	}
+	smc_llc_save_peer_uid(qentry);
+	smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+
+	rc = smc_ib_modify_qp_rts(link_new);
+	if (rc) {
+		smc_llc_send_delete_link(link, link_new->link_id, SMC_LLC_REQ,
+					 false, SMC_LLC_DEL_LOST_PATH);
+		return -ENOLINK;
+	}
+	smc_wr_remember_qp_attr(link_new);
+
+	rc = smcr_buf_reg_lgr(link_new);
+	if (rc) {
+		smc_llc_send_delete_link(link, link_new->link_id, SMC_LLC_REQ,
+					 false, SMC_LLC_DEL_LOST_PATH);
+		return -ENOLINK;
+	}
+
+	/* send CONFIRM LINK response over RoCE fabric */
+	rc = smc_llc_send_confirm_link(link_new, SMC_LLC_RESP);
+	if (rc) {
+		smc_llc_send_delete_link(link, link_new->link_id, SMC_LLC_REQ,
+					 false, SMC_LLC_DEL_LOST_PATH);
+		return -ENOLINK;
+	}
+	smc_llc_link_active(link_new);
+	if (lgr_new_t == SMC_LGR_ASYMMETRIC_LOCAL ||
+	    lgr_new_t == SMC_LGR_ASYMMETRIC_PEER)
+		smcr_lgr_set_type_asym(lgr, lgr_new_t, link_new->link_idx);
+	else
+		smcr_lgr_set_type(lgr, lgr_new_t);
+	return 0;
+}
+
+static void smc_llc_save_add_link_info(struct smc_link *link,
+				       struct smc_llc_msg_add_link *add_llc)
+{
+	link->peer_qpn = ntoh24(add_llc->sender_qp_num);
+	memcpy(link->peer_gid, add_llc->sender_gid, SMC_GID_SIZE);
+	memcpy(link->peer_mac, add_llc->sender_mac, ETH_ALEN);
+	link->peer_psn = ntoh24(add_llc->initial_psn);
+	link->peer_mtu = add_llc->qp_mtu;
+}
+
+/* as an SMC client, process an add link request */
+int smc_llc_cli_add_link(struct smc_link *link, struct smc_llc_qentry *qentry)
+{
+	struct smc_llc_msg_add_link *llc = &qentry->msg.add_link;
+	enum smc_lgr_type lgr_new_t = SMC_LGR_SYMMETRIC;
+	struct smc_link_group *lgr = smc_get_lgr(link);
+	struct smc_link *lnk_new = NULL;
+	struct smc_init_info ini;
+	int lnk_idx, rc = 0;
+
+	if (!llc->qp_mtu)
+		goto out_reject;
+
+	ini.vlan_id = lgr->vlan_id;
+	smc_pnet_find_alt_roce(lgr, &ini, link->smcibdev);
+	if (!memcmp(llc->sender_gid, link->peer_gid, SMC_GID_SIZE) &&
+	    !memcmp(llc->sender_mac, link->peer_mac, ETH_ALEN)) {
+		if (!ini.ib_dev)
+			goto out_reject;
+		lgr_new_t = SMC_LGR_ASYMMETRIC_PEER;
+	}
+	if (!ini.ib_dev) {
+		lgr_new_t = SMC_LGR_ASYMMETRIC_LOCAL;
+		ini.ib_dev = link->smcibdev;
+		ini.ib_port = link->ibport;
+	}
+	lnk_idx = smc_llc_alloc_alt_link(lgr, lgr_new_t);
+	if (lnk_idx < 0)
+		goto out_reject;
+	lnk_new = &lgr->lnk[lnk_idx];
+	rc = smcr_link_init(lgr, lnk_new, lnk_idx, &ini);
+	if (rc)
+		goto out_reject;
+	smc_llc_save_add_link_info(lnk_new, llc);
+	lnk_new->link_id = llc->link_num;	/* SMC server assigns link id */
+	smc_llc_link_set_uid(lnk_new);
+
+	rc = smc_ib_ready_link(lnk_new);
+	if (rc)
+		goto out_clear_lnk;
+
+	rc = smcr_buf_map_lgr(lnk_new);
+	if (rc)
+		goto out_clear_lnk;
+
+	rc = smc_llc_send_add_link(link,
+				   lnk_new->smcibdev->mac[ini.ib_port - 1],
+				   lnk_new->gid, lnk_new, SMC_LLC_RESP);
+	if (rc)
+		goto out_clear_lnk;
+	rc = smc_llc_cli_rkey_exchange(link, lnk_new);
+	if (rc) {
+		rc = 0;
+		goto out_clear_lnk;
+	}
+	rc = smc_llc_cli_conf_link(link, &ini, lnk_new, lgr_new_t);
+	if (!rc)
+		goto out;
+out_clear_lnk:
+	lnk_new->state = SMC_LNK_INACTIVE;
+	smcr_link_clear(lnk_new, false);
+out_reject:
+	smc_llc_cli_add_link_reject(qentry);
+out:
+	kfree(qentry);
+	return rc;
+}
+
+/* as an SMC client, invite server to start the add_link processing */
+static void smc_llc_cli_add_link_invite(struct smc_link *link,
+					struct smc_llc_qentry *qentry)
+{
+	struct smc_link_group *lgr = smc_get_lgr(link);
+	struct smc_init_info ini;
+
+	if (lgr->type == SMC_LGR_SYMMETRIC ||
+	    lgr->type == SMC_LGR_ASYMMETRIC_PEER)
+		goto out;
+
+	ini.vlan_id = lgr->vlan_id;
+	smc_pnet_find_alt_roce(lgr, &ini, link->smcibdev);
+	if (!ini.ib_dev)
+		goto out;
+
+	smc_llc_send_add_link(link, ini.ib_dev->mac[ini.ib_port - 1],
+			      ini.ib_gid, NULL, SMC_LLC_REQ);
+out:
+	kfree(qentry);
+}
+
+static bool smc_llc_is_empty_llc_message(union smc_llc_msg *llc)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(llc->raw.data); i++)
+		if (llc->raw.data[i])
+			return false;
+	return true;
+}
+
+static bool smc_llc_is_local_add_link(union smc_llc_msg *llc)
+{
+	if (llc->raw.hdr.common.type == SMC_LLC_ADD_LINK &&
+	    smc_llc_is_empty_llc_message(llc))
+		return true;
+	return false;
+}
+
+static void smc_llc_process_cli_add_link(struct smc_link_group *lgr)
+{
+	struct smc_llc_qentry *qentry;
+
+	qentry = smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl);
+
+	mutex_lock(&lgr->llc_conf_mutex);
+	if (smc_llc_is_local_add_link(&qentry->msg))
+		smc_llc_cli_add_link_invite(qentry->link, qentry);
+	else
+		smc_llc_cli_add_link(qentry->link, qentry);
+	mutex_unlock(&lgr->llc_conf_mutex);
+}
+
+static int smc_llc_active_link_count(struct smc_link_group *lgr)
+{
+	int i, link_count = 0;
+
+	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+		if (!smc_link_active(&lgr->lnk[i]))
+			continue;
+		link_count++;
+	}
+	return link_count;
+}
+
+/* find the asymmetric link when 3 links are established  */
+static struct smc_link *smc_llc_find_asym_link(struct smc_link_group *lgr)
+{
+	int asym_idx = -ENOENT;
+	int i, j, k;
+	bool found;
+
+	/* determine asymmetric link */
+	found = false;
+	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+		for (j = i + 1; j < SMC_LINKS_PER_LGR_MAX; j++) {
+			if (!smc_link_usable(&lgr->lnk[i]) ||
+			    !smc_link_usable(&lgr->lnk[j]))
+				continue;
+			if (!memcmp(lgr->lnk[i].gid, lgr->lnk[j].gid,
+				    SMC_GID_SIZE)) {
+				found = true;	/* asym_lnk is i or j */
+				break;
+			}
+		}
+		if (found)
+			break;
+	}
+	if (!found)
+		goto out; /* no asymmetric link */
+	for (k = 0; k < SMC_LINKS_PER_LGR_MAX; k++) {
+		if (!smc_link_usable(&lgr->lnk[k]))
+			continue;
+		if (k != i &&
+		    !memcmp(lgr->lnk[i].peer_gid, lgr->lnk[k].peer_gid,
+			    SMC_GID_SIZE)) {
+			asym_idx = i;
+			break;
+		}
+		if (k != j &&
+		    !memcmp(lgr->lnk[j].peer_gid, lgr->lnk[k].peer_gid,
+			    SMC_GID_SIZE)) {
+			asym_idx = j;
+			break;
+		}
+	}
+out:
+	return (asym_idx < 0) ? NULL : &lgr->lnk[asym_idx];
+}
+
+static void smc_llc_delete_asym_link(struct smc_link_group *lgr)
+{
+	struct smc_link *lnk_new = NULL, *lnk_asym;
+	struct smc_llc_qentry *qentry;
+	int rc;
+
+	lnk_asym = smc_llc_find_asym_link(lgr);
+	if (!lnk_asym)
+		return; /* no asymmetric link */
+	if (!smc_link_downing(&lnk_asym->state))
+		return;
+	lnk_new = smc_switch_conns(lgr, lnk_asym, false);
+	smc_wr_tx_wait_no_pending_sends(lnk_asym);
+	if (!lnk_new)
+		goto out_free;
+	/* change flow type from ADD_LINK into DEL_LINK */
+	lgr->llc_flow_lcl.type = SMC_LLC_FLOW_DEL_LINK;
+	rc = smc_llc_send_delete_link(lnk_new, lnk_asym->link_id, SMC_LLC_REQ,
+				      true, SMC_LLC_DEL_NO_ASYM_NEEDED);
+	if (rc) {
+		smcr_link_down_cond(lnk_new);
+		goto out_free;
+	}
+	qentry = smc_llc_wait(lgr, lnk_new, SMC_LLC_WAIT_TIME,
+			      SMC_LLC_DELETE_LINK);
+	if (!qentry) {
+		smcr_link_down_cond(lnk_new);
+		goto out_free;
+	}
+	smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+out_free:
+	smcr_link_clear(lnk_asym, true);
+}
+
+static int smc_llc_srv_rkey_exchange(struct smc_link *link,
+				     struct smc_link *link_new)
+{
+	struct smc_llc_msg_add_link_cont *addc_llc;
+	struct smc_link_group *lgr = link->lgr;
+	u8 max, num_rkeys_send, num_rkeys_recv;
+	struct smc_llc_qentry *qentry = NULL;
+	struct smc_buf_desc *buf_pos;
+	int buf_lst;
+	int rc = 0;
+	int i;
+
+	mutex_lock(&lgr->rmbs_lock);
+	num_rkeys_send = lgr->conns_num;
+	buf_pos = smc_llc_get_first_rmb(lgr, &buf_lst);
+	do {
+		smc_llc_add_link_cont(link, link_new, &num_rkeys_send,
+				      &buf_lst, &buf_pos);
+		qentry = smc_llc_wait(lgr, link, SMC_LLC_WAIT_TIME,
+				      SMC_LLC_ADD_LINK_CONT);
+		if (!qentry) {
+			rc = -ETIMEDOUT;
+			goto out;
+		}
+		addc_llc = &qentry->msg.add_link_cont;
+		num_rkeys_recv = addc_llc->num_rkeys;
+		max = min_t(u8, num_rkeys_recv, SMC_LLC_RKEYS_PER_CONT_MSG);
+		for (i = 0; i < max; i++) {
+			smc_rtoken_set(lgr, link->link_idx, link_new->link_idx,
+				       addc_llc->rt[i].rmb_key,
+				       addc_llc->rt[i].rmb_vaddr_new,
+				       addc_llc->rt[i].rmb_key_new);
+			num_rkeys_recv--;
+		}
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+	} while (num_rkeys_send || num_rkeys_recv);
+out:
+	mutex_unlock(&lgr->rmbs_lock);
+	return rc;
+}
+
+static int smc_llc_srv_conf_link(struct smc_link *link,
+				 struct smc_link *link_new,
+				 enum smc_lgr_type lgr_new_t)
+{
+	struct smc_link_group *lgr = link->lgr;
+	struct smc_llc_qentry *qentry = NULL;
+	int rc;
+
+	/* send CONFIRM LINK request over the RoCE fabric */
+	rc = smc_llc_send_confirm_link(link_new, SMC_LLC_REQ);
+	if (rc)
+		return -ENOLINK;
+	/* receive CONFIRM LINK response over the RoCE fabric */
+	qentry = smc_llc_wait(lgr, link, SMC_LLC_WAIT_FIRST_TIME, 0);
+	if (!qentry ||
+	    qentry->msg.raw.hdr.common.type != SMC_LLC_CONFIRM_LINK) {
+		/* send DELETE LINK */
+		smc_llc_send_delete_link(link, link_new->link_id, SMC_LLC_REQ,
+					 false, SMC_LLC_DEL_LOST_PATH);
+		if (qentry)
+			smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		return -ENOLINK;
+	}
+	smc_llc_save_peer_uid(qentry);
+	smc_llc_link_active(link_new);
+	if (lgr_new_t == SMC_LGR_ASYMMETRIC_LOCAL ||
+	    lgr_new_t == SMC_LGR_ASYMMETRIC_PEER)
+		smcr_lgr_set_type_asym(lgr, lgr_new_t, link_new->link_idx);
+	else
+		smcr_lgr_set_type(lgr, lgr_new_t);
+	smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+	return 0;
+}
+
+int smc_llc_srv_add_link(struct smc_link *link)
+{
+	enum smc_lgr_type lgr_new_t = SMC_LGR_SYMMETRIC;
+	struct smc_link_group *lgr = link->lgr;
+	struct smc_llc_msg_add_link *add_llc;
+	struct smc_llc_qentry *qentry = NULL;
+	struct smc_link *link_new;
+	struct smc_init_info ini;
+	int lnk_idx, rc = 0;
+
+	/* ignore client add link recommendation, start new flow */
+	ini.vlan_id = lgr->vlan_id;
+	smc_pnet_find_alt_roce(lgr, &ini, link->smcibdev);
+	if (!ini.ib_dev) {
+		lgr_new_t = SMC_LGR_ASYMMETRIC_LOCAL;
+		ini.ib_dev = link->smcibdev;
+		ini.ib_port = link->ibport;
+	}
+	lnk_idx = smc_llc_alloc_alt_link(lgr, lgr_new_t);
+	if (lnk_idx < 0)
+		return 0;
+
+	rc = smcr_link_init(lgr, &lgr->lnk[lnk_idx], lnk_idx, &ini);
+	if (rc)
+		return rc;
+	link_new = &lgr->lnk[lnk_idx];
+	rc = smc_llc_send_add_link(link,
+				   link_new->smcibdev->mac[ini.ib_port - 1],
+				   link_new->gid, link_new, SMC_LLC_REQ);
+	if (rc)
+		goto out_err;
+	/* receive ADD LINK response over the RoCE fabric */
+	qentry = smc_llc_wait(lgr, link, SMC_LLC_WAIT_TIME, SMC_LLC_ADD_LINK);
+	if (!qentry) {
+		rc = -ETIMEDOUT;
+		goto out_err;
+	}
+	add_llc = &qentry->msg.add_link;
+	if (add_llc->hd.flags & SMC_LLC_FLAG_ADD_LNK_REJ) {
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		rc = -ENOLINK;
+		goto out_err;
+	}
+	if (lgr->type == SMC_LGR_SINGLE &&
+	    (!memcmp(add_llc->sender_gid, link->peer_gid, SMC_GID_SIZE) &&
+	     !memcmp(add_llc->sender_mac, link->peer_mac, ETH_ALEN))) {
+		lgr_new_t = SMC_LGR_ASYMMETRIC_PEER;
+	}
+	smc_llc_save_add_link_info(link_new, add_llc);
+	smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+
+	rc = smc_ib_ready_link(link_new);
+	if (rc)
+		goto out_err;
+	rc = smcr_buf_map_lgr(link_new);
+	if (rc)
+		goto out_err;
+	rc = smcr_buf_reg_lgr(link_new);
+	if (rc)
+		goto out_err;
+	rc = smc_llc_srv_rkey_exchange(link, link_new);
+	if (rc)
+		goto out_err;
+	rc = smc_llc_srv_conf_link(link, link_new, lgr_new_t);
+	if (rc)
+		goto out_err;
+	return 0;
+out_err:
+	link_new->state = SMC_LNK_INACTIVE;
+	smcr_link_clear(link_new, false);
+	return rc;
+}
+
+static void smc_llc_process_srv_add_link(struct smc_link_group *lgr)
+{
+	struct smc_link *link = lgr->llc_flow_lcl.qentry->link;
+	int rc;
+
+	smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+
+	mutex_lock(&lgr->llc_conf_mutex);
+	rc = smc_llc_srv_add_link(link);
+	if (!rc && lgr->type == SMC_LGR_SYMMETRIC) {
+		/* delete any asymmetric link */
+		smc_llc_delete_asym_link(lgr);
+	}
+	mutex_unlock(&lgr->llc_conf_mutex);
+}
+
+/* enqueue a local add_link req to trigger a new add_link flow */
+void smc_llc_add_link_local(struct smc_link *link)
+{
+	struct smc_llc_msg_add_link add_llc = {};
+
+	add_llc.hd.length = sizeof(add_llc);
+	add_llc.hd.common.type = SMC_LLC_ADD_LINK;
+	/* no dev and port needed */
+	smc_llc_enqueue(link, (union smc_llc_msg *)&add_llc);
+}
+
+/* worker to process an add link message */
+static void smc_llc_add_link_work(struct work_struct *work)
+{
+	struct smc_link_group *lgr = container_of(work, struct smc_link_group,
+						  llc_add_link_work);
+
+	if (list_empty(&lgr->list)) {
+		/* link group is terminating */
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		goto out;
+	}
+
+	if (lgr->role == SMC_CLNT)
+		smc_llc_process_cli_add_link(lgr);
+	else
+		smc_llc_process_srv_add_link(lgr);
+out:
+	smc_llc_flow_stop(lgr, &lgr->llc_flow_lcl);
+}
+
+/* enqueue a local del_link msg to trigger a new del_link flow,
+ * called only for role SMC_SERV
+ */
+void smc_llc_srv_delete_link_local(struct smc_link *link, u8 del_link_id)
+{
+	struct smc_llc_msg_del_link del_llc = {};
+
+	del_llc.hd.length = sizeof(del_llc);
+	del_llc.hd.common.type = SMC_LLC_DELETE_LINK;
+	del_llc.link_num = del_link_id;
+	del_llc.reason = htonl(SMC_LLC_DEL_LOST_PATH);
+	del_llc.hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
+	smc_llc_enqueue(link, (union smc_llc_msg *)&del_llc);
+}
+
+static void smc_llc_process_cli_delete_link(struct smc_link_group *lgr)
+{
+	struct smc_link *lnk_del = NULL, *lnk_asym, *lnk;
+	struct smc_llc_msg_del_link *del_llc;
+	struct smc_llc_qentry *qentry;
+	int active_links;
+	int lnk_idx;
+
+	qentry = smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl);
+	lnk = qentry->link;
+	del_llc = &qentry->msg.delete_link;
+
+	if (del_llc->hd.flags & SMC_LLC_FLAG_DEL_LINK_ALL) {
+		smc_lgr_terminate_sched(lgr);
+		goto out;
+	}
+	mutex_lock(&lgr->llc_conf_mutex);
+	/* delete single link */
+	for (lnk_idx = 0; lnk_idx < SMC_LINKS_PER_LGR_MAX; lnk_idx++) {
+		if (lgr->lnk[lnk_idx].link_id != del_llc->link_num)
+			continue;
+		lnk_del = &lgr->lnk[lnk_idx];
+		break;
+	}
+	del_llc->hd.flags |= SMC_LLC_FLAG_RESP;
+	if (!lnk_del) {
+		/* link was not found */
+		del_llc->reason = htonl(SMC_LLC_DEL_NOLNK);
+		smc_llc_send_message(lnk, &qentry->msg);
+		goto out_unlock;
+	}
+	lnk_asym = smc_llc_find_asym_link(lgr);
+
+	del_llc->reason = 0;
+	smc_llc_send_message(lnk, &qentry->msg); /* response */
+
+	if (smc_link_downing(&lnk_del->state))
+		smc_switch_conns(lgr, lnk_del, false);
+	smcr_link_clear(lnk_del, true);
+
+	active_links = smc_llc_active_link_count(lgr);
+	if (lnk_del == lnk_asym) {
+		/* expected deletion of asym link, don't change lgr state */
+	} else if (active_links == 1) {
+		smcr_lgr_set_type(lgr, SMC_LGR_SINGLE);
+	} else if (!active_links) {
+		smcr_lgr_set_type(lgr, SMC_LGR_NONE);
+		smc_lgr_terminate_sched(lgr);
+	}
+out_unlock:
+	mutex_unlock(&lgr->llc_conf_mutex);
+out:
+	kfree(qentry);
+}
+
+/* try to send a DELETE LINK ALL request on any active link,
+ * waiting for send completion
+ */
+void smc_llc_send_link_delete_all(struct smc_link_group *lgr, bool ord, u32 rsn)
+{
+	struct smc_llc_msg_del_link delllc = {};
+	int i;
+
+	delllc.hd.common.type = SMC_LLC_DELETE_LINK;
+	delllc.hd.length = sizeof(delllc);
+	if (ord)
+		delllc.hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
+	delllc.hd.flags |= SMC_LLC_FLAG_DEL_LINK_ALL;
+	delllc.reason = htonl(rsn);
+
+	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+		if (!smc_link_sendable(&lgr->lnk[i]))
+			continue;
+		if (!smc_llc_send_message_wait(&lgr->lnk[i], &delllc))
+			break;
+	}
+}
+
+static void smc_llc_process_srv_delete_link(struct smc_link_group *lgr)
+{
+	struct smc_llc_msg_del_link *del_llc;
+	struct smc_link *lnk, *lnk_del;
+	struct smc_llc_qentry *qentry;
+	int active_links;
+	int i;
+
+	mutex_lock(&lgr->llc_conf_mutex);
+	qentry = smc_llc_flow_qentry_clr(&lgr->llc_flow_lcl);
+	lnk = qentry->link;
+	del_llc = &qentry->msg.delete_link;
+
+	if (qentry->msg.delete_link.hd.flags & SMC_LLC_FLAG_DEL_LINK_ALL) {
+		/* delete entire lgr */
+		smc_llc_send_link_delete_all(lgr, true, ntohl(
+					      qentry->msg.delete_link.reason));
+		smc_lgr_terminate_sched(lgr);
+		goto out;
+	}
+	/* delete single link */
+	lnk_del = NULL;
+	for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+		if (lgr->lnk[i].link_id == del_llc->link_num) {
+			lnk_del = &lgr->lnk[i];
+			break;
+		}
+	}
+	if (!lnk_del)
+		goto out; /* asymmetric link already deleted */
+
+	if (smc_link_downing(&lnk_del->state)) {
+		if (smc_switch_conns(lgr, lnk_del, false))
+			smc_wr_tx_wait_no_pending_sends(lnk_del);
+	}
+	if (!list_empty(&lgr->list)) {
+		/* qentry is either a request from peer (send it back to
+		 * initiate the DELETE_LINK processing), or a locally
+		 * enqueued DELETE_LINK request (forward it)
+		 */
+		if (!smc_llc_send_message(lnk, &qentry->msg)) {
+			struct smc_llc_qentry *qentry2;
+
+			qentry2 = smc_llc_wait(lgr, lnk, SMC_LLC_WAIT_TIME,
+					       SMC_LLC_DELETE_LINK);
+			if (qentry2)
+				smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		}
+	}
+	smcr_link_clear(lnk_del, true);
+
+	active_links = smc_llc_active_link_count(lgr);
+	if (active_links == 1) {
+		smcr_lgr_set_type(lgr, SMC_LGR_SINGLE);
+	} else if (!active_links) {
+		smcr_lgr_set_type(lgr, SMC_LGR_NONE);
+		smc_lgr_terminate_sched(lgr);
+	}
+
+	if (lgr->type == SMC_LGR_SINGLE && !list_empty(&lgr->list)) {
+		/* trigger setup of asymm alt link */
+		smc_llc_add_link_local(lnk);
+	}
+out:
+	mutex_unlock(&lgr->llc_conf_mutex);
+	kfree(qentry);
+}
+
+static void smc_llc_delete_link_work(struct work_struct *work)
+{
+	struct smc_link_group *lgr = container_of(work, struct smc_link_group,
+						  llc_del_link_work);
+
+	if (list_empty(&lgr->list)) {
+		/* link group is terminating */
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+		goto out;
+	}
+
+	if (lgr->role == SMC_CLNT)
+		smc_llc_process_cli_delete_link(lgr);
+	else
+		smc_llc_process_srv_delete_link(lgr);
+out:
+	smc_llc_flow_stop(lgr, &lgr->llc_flow_lcl);
+}
+
+/* process a confirm_rkey request from peer, remote flow */
+static void smc_llc_rmt_conf_rkey(struct smc_link_group *lgr)
+{
+	struct smc_llc_msg_confirm_rkey *llc;
+	struct smc_llc_qentry *qentry;
+	struct smc_link *link;
+	int num_entries;
+	int rk_idx;
+	int i;
+
+	qentry = lgr->llc_flow_rmt.qentry;
+	llc = &qentry->msg.confirm_rkey;
+	link = qentry->link;
+
+	num_entries = llc->rtoken[0].num_rkeys;
+	/* first rkey entry is for receiving link */
+	rk_idx = smc_rtoken_add(link,
+				llc->rtoken[0].rmb_vaddr,
+				llc->rtoken[0].rmb_key);
+	if (rk_idx < 0)
+		goto out_err;
+
+	for (i = 1; i <= min_t(u8, num_entries, SMC_LLC_RKEYS_PER_MSG - 1); i++)
+		smc_rtoken_set2(lgr, rk_idx, llc->rtoken[i].link_id,
+				llc->rtoken[i].rmb_vaddr,
+				llc->rtoken[i].rmb_key);
+	/* max links is 3 so there is no need to support conf_rkey_cont msgs */
+	goto out;
+out_err:
+	llc->hd.flags |= SMC_LLC_FLAG_RKEY_NEG;
+	llc->hd.flags |= SMC_LLC_FLAG_RKEY_RETRY;
+out:
+	llc->hd.flags |= SMC_LLC_FLAG_RESP;
+	smc_llc_send_message(link, &qentry->msg);
+	smc_llc_flow_qentry_del(&lgr->llc_flow_rmt);
+}
+
+/* process a delete_rkey request from peer, remote flow */
+static void smc_llc_rmt_delete_rkey(struct smc_link_group *lgr)
+{
+	struct smc_llc_msg_delete_rkey *llc;
+	struct smc_llc_qentry *qentry;
+	struct smc_link *link;
+	u8 err_mask = 0;
+	int i, max;
+
+	qentry = lgr->llc_flow_rmt.qentry;
+	llc = &qentry->msg.delete_rkey;
+	link = qentry->link;
+
+	max = min_t(u8, llc->num_rkeys, SMC_LLC_DEL_RKEY_MAX);
+	for (i = 0; i < max; i++) {
+		if (smc_rtoken_delete(link, llc->rkey[i]))
+			err_mask |= 1 << (SMC_LLC_DEL_RKEY_MAX - 1 - i);
+	}
+	if (err_mask) {
+		llc->hd.flags |= SMC_LLC_FLAG_RKEY_NEG;
+		llc->err_mask = err_mask;
+	}
+	llc->hd.flags |= SMC_LLC_FLAG_RESP;
+	smc_llc_send_message(link, &qentry->msg);
+	smc_llc_flow_qentry_del(&lgr->llc_flow_rmt);
+}
+
+static void smc_llc_protocol_violation(struct smc_link_group *lgr, u8 type)
+{
+	pr_warn_ratelimited("smc: SMC-R lg %*phN LLC protocol violation: "
+			    "llc_type %d\n", SMC_LGR_ID_SIZE, &lgr->id, type);
+	smc_llc_set_termination_rsn(lgr, SMC_LLC_DEL_PROT_VIOL);
+	smc_lgr_terminate_sched(lgr);
+}
+
+/* flush the llc event queue */
+static void smc_llc_event_flush(struct smc_link_group *lgr)
+{
+	struct smc_llc_qentry *qentry, *q;
+
+	spin_lock_bh(&lgr->llc_event_q_lock);
+	list_for_each_entry_safe(qentry, q, &lgr->llc_event_q, list) {
+		list_del_init(&qentry->list);
+		kfree(qentry);
+	}
+	spin_unlock_bh(&lgr->llc_event_q_lock);
+}
+
+static void smc_llc_event_handler(struct smc_llc_qentry *qentry)
+{
+	union smc_llc_msg *llc = &qentry->msg;
+	struct smc_link *link = qentry->link;
+	struct smc_link_group *lgr = link->lgr;
+
+	if (!smc_link_usable(link))
+		goto out;
+
+	switch (llc->raw.hdr.common.type) {
+	case SMC_LLC_TEST_LINK:
+		llc->test_link.hd.flags |= SMC_LLC_FLAG_RESP;
+		smc_llc_send_message(link, llc);
+		break;
+	case SMC_LLC_ADD_LINK:
+		if (list_empty(&lgr->list))
+			goto out;	/* lgr is terminating */
+		if (lgr->role == SMC_CLNT) {
+			if (smc_llc_is_local_add_link(llc)) {
+				if (lgr->llc_flow_lcl.type ==
+				    SMC_LLC_FLOW_ADD_LINK)
+					break;	/* add_link in progress */
+				if (smc_llc_flow_start(&lgr->llc_flow_lcl,
+						       qentry)) {
+					schedule_work(&lgr->llc_add_link_work);
+				}
+				return;
+			}
+			if (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_ADD_LINK &&
+			    !lgr->llc_flow_lcl.qentry) {
+				/* a flow is waiting for this message */
+				smc_llc_flow_qentry_set(&lgr->llc_flow_lcl,
+							qentry);
+				wake_up(&lgr->llc_msg_waiter);
+			} else if (smc_llc_flow_start(&lgr->llc_flow_lcl,
+						      qentry)) {
+				schedule_work(&lgr->llc_add_link_work);
+			}
+		} else if (smc_llc_flow_start(&lgr->llc_flow_lcl, qentry)) {
+			/* as smc server, handle client suggestion */
+			schedule_work(&lgr->llc_add_link_work);
+		}
+		return;
+	case SMC_LLC_CONFIRM_LINK:
+	case SMC_LLC_ADD_LINK_CONT:
+		if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
+			/* a flow is waiting for this message */
+			smc_llc_flow_qentry_set(&lgr->llc_flow_lcl, qentry);
+			wake_up(&lgr->llc_msg_waiter);
+			return;
+		}
+		break;
+	case SMC_LLC_DELETE_LINK:
+		if (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_ADD_LINK &&
+		    !lgr->llc_flow_lcl.qentry) {
+			/* DEL LINK REQ during ADD LINK SEQ */
+			smc_llc_flow_qentry_set(&lgr->llc_flow_lcl, qentry);
+			wake_up(&lgr->llc_msg_waiter);
+		} else if (smc_llc_flow_start(&lgr->llc_flow_lcl, qentry)) {
+			schedule_work(&lgr->llc_del_link_work);
+		}
+		return;
+	case SMC_LLC_CONFIRM_RKEY:
+		/* new request from remote, assign to remote flow */
+		if (smc_llc_flow_start(&lgr->llc_flow_rmt, qentry)) {
+			/* process here, does not wait for more llc msgs */
+			smc_llc_rmt_conf_rkey(lgr);
+			smc_llc_flow_stop(lgr, &lgr->llc_flow_rmt);
+		}
+		return;
+	case SMC_LLC_CONFIRM_RKEY_CONT:
+		/* not used because max links is 3, and 3 rkeys fit into
+		 * one CONFIRM_RKEY message
+		 */
+		break;
+	case SMC_LLC_DELETE_RKEY:
+		/* new request from remote, assign to remote flow */
+		if (smc_llc_flow_start(&lgr->llc_flow_rmt, qentry)) {
+			/* process here, does not wait for more llc msgs */
+			smc_llc_rmt_delete_rkey(lgr);
+			smc_llc_flow_stop(lgr, &lgr->llc_flow_rmt);
+		}
+		return;
+	default:
+		smc_llc_protocol_violation(lgr, llc->raw.hdr.common.type);
+		break;
+	}
+out:
+	kfree(qentry);
+}
+
+/* worker to process llc messages on the event queue */
+static void smc_llc_event_work(struct work_struct *work)
+{
+	struct smc_link_group *lgr = container_of(work, struct smc_link_group,
+						  llc_event_work);
+	struct smc_llc_qentry *qentry;
+
+	if (!lgr->llc_flow_lcl.type && lgr->delayed_event) {
+		qentry = lgr->delayed_event;
+		lgr->delayed_event = NULL;
+		if (smc_link_usable(qentry->link))
+			smc_llc_event_handler(qentry);
+		else
+			kfree(qentry);
+	}
+
+again:
+	spin_lock_bh(&lgr->llc_event_q_lock);
+	if (!list_empty(&lgr->llc_event_q)) {
+		qentry = list_first_entry(&lgr->llc_event_q,
+					  struct smc_llc_qentry, list);
+		list_del_init(&qentry->list);
+		spin_unlock_bh(&lgr->llc_event_q_lock);
+		smc_llc_event_handler(qentry);
+		goto again;
+	}
+	spin_unlock_bh(&lgr->llc_event_q_lock);
+}
+
+/* process llc responses in tasklet context */
+static void smc_llc_rx_response(struct smc_link *link,
+				struct smc_llc_qentry *qentry)
+{
+	enum smc_llc_flowtype flowtype = link->lgr->llc_flow_lcl.type;
+	struct smc_llc_flow *flow = &link->lgr->llc_flow_lcl;
+	u8 llc_type = qentry->msg.raw.hdr.common.type;
+
+	switch (llc_type) {
+	case SMC_LLC_TEST_LINK:
+		if (smc_link_active(link))
+			complete(&link->llc_testlink_resp);
+		break;
+	case SMC_LLC_ADD_LINK:
+	case SMC_LLC_ADD_LINK_CONT:
+	case SMC_LLC_CONFIRM_LINK:
+		if (flowtype != SMC_LLC_FLOW_ADD_LINK || flow->qentry)
+			break;	/* drop out-of-flow response */
+		goto assign;
+	case SMC_LLC_DELETE_LINK:
+		if (flowtype != SMC_LLC_FLOW_DEL_LINK || flow->qentry)
+			break;	/* drop out-of-flow response */
+		goto assign;
+	case SMC_LLC_CONFIRM_RKEY:
+	case SMC_LLC_DELETE_RKEY:
+		if (flowtype != SMC_LLC_FLOW_RKEY || flow->qentry)
+			break;	/* drop out-of-flow response */
+		goto assign;
+	case SMC_LLC_CONFIRM_RKEY_CONT:
+		/* not used because max links is 3 */
+		break;
+	default:
+		smc_llc_protocol_violation(link->lgr, llc_type);
+		break;
+	}
+	kfree(qentry);
+	return;
+assign:
+	/* assign responses to the local flow, we requested them */
+	smc_llc_flow_qentry_set(&link->lgr->llc_flow_lcl, qentry);
+	wake_up(&link->lgr->llc_msg_waiter);
+}
+
+static void smc_llc_enqueue(struct smc_link *link, union smc_llc_msg *llc)
+{
+	struct smc_link_group *lgr = link->lgr;
+	struct smc_llc_qentry *qentry;
+	unsigned long flags;
+
+	qentry = kmalloc(sizeof(*qentry), GFP_ATOMIC);
+	if (!qentry)
+		return;
+	qentry->link = link;
+	INIT_LIST_HEAD(&qentry->list);
+	memcpy(&qentry->msg, llc, sizeof(union smc_llc_msg));
+
+	/* process responses immediately */
+	if (llc->raw.hdr.flags & SMC_LLC_FLAG_RESP) {
+		smc_llc_rx_response(link, qentry);
+		return;
+	}
+
+	/* add requests to event queue */
+	spin_lock_irqsave(&lgr->llc_event_q_lock, flags);
+	list_add_tail(&qentry->list, &lgr->llc_event_q);
+	spin_unlock_irqrestore(&lgr->llc_event_q_lock, flags);
+	queue_work(system_highpri_wq, &lgr->llc_event_work);
+}
+
+/* copy received msg and add it to the event queue */
+static void smc_llc_rx_handler(struct ib_wc *wc, void *buf)
+{
+	struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
+	union smc_llc_msg *llc = buf;
+
+	if (wc->byte_len < sizeof(*llc))
+		return; /* short message */
+	if (llc->raw.hdr.length != sizeof(*llc))
+		return; /* invalid message */
+
+	smc_llc_enqueue(link, llc);
+}
+
+/***************************** worker, utils *********************************/
+
+static void smc_llc_testlink_work(struct work_struct *work)
+{
+	struct smc_link *link = container_of(to_delayed_work(work),
+					     struct smc_link, llc_testlink_wrk);
+	unsigned long next_interval;
+	unsigned long expire_time;
+	u8 user_data[16] = { 0 };
+	int rc;
+
+	if (!smc_link_active(link))
+		return;		/* don't reschedule worker */
+	expire_time = link->wr_rx_tstamp + link->llc_testlink_time;
+	if (time_is_after_jiffies(expire_time)) {
+		next_interval = expire_time - jiffies;
+		goto out;
+	}
+	reinit_completion(&link->llc_testlink_resp);
+	smc_llc_send_test_link(link, user_data);
+	/* receive TEST LINK response over RoCE fabric */
+	rc = wait_for_completion_interruptible_timeout(&link->llc_testlink_resp,
+						       SMC_LLC_WAIT_TIME);
+	if (!smc_link_active(link))
+		return;		/* link state changed */
+	if (rc <= 0) {
+		smcr_link_down_cond_sched(link);
+		return;
+	}
+	next_interval = link->llc_testlink_time;
+out:
+	schedule_delayed_work(&link->llc_testlink_wrk, next_interval);
+}
+
+void smc_llc_lgr_init(struct smc_link_group *lgr, struct smc_sock *smc)
+{
+	struct net *net = sock_net(smc->clcsock->sk);
+
+	INIT_WORK(&lgr->llc_event_work, smc_llc_event_work);
+	INIT_WORK(&lgr->llc_add_link_work, smc_llc_add_link_work);
+	INIT_WORK(&lgr->llc_del_link_work, smc_llc_delete_link_work);
+	INIT_LIST_HEAD(&lgr->llc_event_q);
+	spin_lock_init(&lgr->llc_event_q_lock);
+	spin_lock_init(&lgr->llc_flow_lock);
+	init_waitqueue_head(&lgr->llc_flow_waiter);
+	init_waitqueue_head(&lgr->llc_msg_waiter);
+	mutex_init(&lgr->llc_conf_mutex);
+	lgr->llc_testlink_time = READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
+}
+
+/* called after lgr was removed from lgr_list */
+void smc_llc_lgr_clear(struct smc_link_group *lgr)
+{
+	smc_llc_event_flush(lgr);
+	wake_up_all(&lgr->llc_flow_waiter);
+	wake_up_all(&lgr->llc_msg_waiter);
+	cancel_work_sync(&lgr->llc_event_work);
+	cancel_work_sync(&lgr->llc_add_link_work);
+	cancel_work_sync(&lgr->llc_del_link_work);
+	if (lgr->delayed_event) {
+		kfree(lgr->delayed_event);
+		lgr->delayed_event = NULL;
+	}
+}
+
+int smc_llc_link_init(struct smc_link *link)
+{
+	init_completion(&link->llc_testlink_resp);
+	INIT_DELAYED_WORK(&link->llc_testlink_wrk, smc_llc_testlink_work);
+	return 0;
+}
+
+void smc_llc_link_active(struct smc_link *link)
+{
+	pr_warn_ratelimited("smc: SMC-R lg %*phN link added: id %*phN, "
+			    "peerid %*phN, ibdev %s, ibport %d\n",
+			    SMC_LGR_ID_SIZE, &link->lgr->id,
+			    SMC_LGR_ID_SIZE, &link->link_uid,
+			    SMC_LGR_ID_SIZE, &link->peer_link_uid,
+			    link->smcibdev->ibdev->name, link->ibport);
+	link->state = SMC_LNK_ACTIVE;
+	if (link->lgr->llc_testlink_time) {
+		link->llc_testlink_time = link->lgr->llc_testlink_time;
+		schedule_delayed_work(&link->llc_testlink_wrk,
+				      link->llc_testlink_time);
+	}
+}
+
+/* called in worker context */
+void smc_llc_link_clear(struct smc_link *link, bool log)
+{
+	if (log)
+		pr_warn_ratelimited("smc: SMC-R lg %*phN link removed: id %*phN"
+				    ", peerid %*phN, ibdev %s, ibport %d\n",
+				    SMC_LGR_ID_SIZE, &link->lgr->id,
+				    SMC_LGR_ID_SIZE, &link->link_uid,
+				    SMC_LGR_ID_SIZE, &link->peer_link_uid,
+				    link->smcibdev->ibdev->name, link->ibport);
+	complete(&link->llc_testlink_resp);
+	cancel_delayed_work_sync(&link->llc_testlink_wrk);
+}
+
+/* register a new rtoken at the remote peer (for all links) */
+int smc_llc_do_confirm_rkey(struct smc_link *send_link,
+			    struct smc_buf_desc *rmb_desc)
+{
+	struct smc_link_group *lgr = send_link->lgr;
+	struct smc_llc_qentry *qentry = NULL;
+	int rc = 0;
+
+	rc = smc_llc_send_confirm_rkey(send_link, rmb_desc);
+	if (rc)
+		goto out;
+	/* receive CONFIRM RKEY response from server over RoCE fabric */
+	qentry = smc_llc_wait(lgr, send_link, SMC_LLC_WAIT_TIME,
+			      SMC_LLC_CONFIRM_RKEY);
+	if (!qentry || (qentry->msg.raw.hdr.flags & SMC_LLC_FLAG_RKEY_NEG))
+		rc = -EFAULT;
+out:
+	if (qentry)
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+	return rc;
+}
+
+/* unregister an rtoken at the remote peer */
+int smc_llc_do_delete_rkey(struct smc_link_group *lgr,
+			   struct smc_buf_desc *rmb_desc)
+{
+	struct smc_llc_qentry *qentry = NULL;
+	struct smc_link *send_link;
+	int rc = 0;
+
+	send_link = smc_llc_usable_link(lgr);
+	if (!send_link)
+		return -ENOLINK;
+
+	/* protected by llc_flow control */
+	rc = smc_llc_send_delete_rkey(send_link, rmb_desc);
+	if (rc)
+		goto out;
+	/* receive DELETE RKEY response from server over RoCE fabric */
+	qentry = smc_llc_wait(lgr, send_link, SMC_LLC_WAIT_TIME,
+			      SMC_LLC_DELETE_RKEY);
+	if (!qentry || (qentry->msg.raw.hdr.flags & SMC_LLC_FLAG_RKEY_NEG))
+		rc = -EFAULT;
+out:
+	if (qentry)
+		smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+	return rc;
+}
+
+void smc_llc_link_set_uid(struct smc_link *link)
+{
+	__be32 link_uid;
+
+	link_uid = htonl(*((u32 *)link->lgr->id) + link->link_id);
+	memcpy(link->link_uid, &link_uid, SMC_LGR_ID_SIZE);
+}
+
+/* save peers link user id, used for debug purposes */
+void smc_llc_save_peer_uid(struct smc_llc_qentry *qentry)
+{
+	memcpy(qentry->link->peer_link_uid, qentry->msg.confirm_link.link_uid,
+	       SMC_LGR_ID_SIZE);
+}
+
+/* evaluate confirm link request or response */
+int smc_llc_eval_conf_link(struct smc_llc_qentry *qentry,
+			   enum smc_llc_reqresp type)
+{
+	if (type == SMC_LLC_REQ) {	/* SMC server assigns link_id */
+		qentry->link->link_id = qentry->msg.confirm_link.link_num;
+		smc_llc_link_set_uid(qentry->link);
+	}
+	if (!(qentry->msg.raw.hdr.flags & SMC_LLC_FLAG_NO_RMBE_EYEC))
+		return -ENOTSUPP;
+	return 0;
+}
+
+/***************************** init, exit, misc ******************************/
+
+static struct smc_wr_rx_handler smc_llc_rx_handlers[] = {
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_CONFIRM_LINK
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_TEST_LINK
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_ADD_LINK
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_ADD_LINK_CONT
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_DELETE_LINK
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_CONFIRM_RKEY
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_CONFIRM_RKEY_CONT
+	},
+	{
+		.handler	= smc_llc_rx_handler,
+		.type		= SMC_LLC_DELETE_RKEY
+	},
+	{
+		.handler	= NULL,
+	}
+};
+
+int __init smc_llc_init(void)
+{
+	struct smc_wr_rx_handler *handler;
+	int rc = 0;
+
+	for (handler = smc_llc_rx_handlers; handler->handler; handler++) {
+		INIT_HLIST_NODE(&handler->list);
+		rc = smc_wr_rx_register_handler(handler);
+		if (rc)
+			break;
+	}
+	return rc;
+}