net/smc: support max links per lgr negotiation in clc handshake

Support max links per lgr negotiation in clc handshake for SMCR v2.1,
which is one of smc v2.1 features. Server makes decision for the final
value of max links based on the client preferred max links and
self-preferred max links. Here use the minimum value of the client
preferred max links and server preferred max links.

Client                                       Server
     Proposal(max links(client preferred))
     -------------------------------------->

     Accept(max links(accepted value))
accepted value=min(client preferred, server preferred)
     <-------------------------------------

      Confirm(max links(accepted value))
     ------------------------------------->

Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Reviewed-by: Jan Karcher <jaka@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: GuangguanWang

net/smc/af_smc.c

@@ -641,20 +641,22 @@ static int smcr_clnt_conf_first_link(struct smc_sock *smc)
 	smc_llc_link_active(link);
 	smcr_lgr_set_type(link->lgr, SMC_LGR_SINGLE);
 
-	/* optional 2nd link, receive ADD LINK request from server */
-	qentry = smc_llc_wait(link->lgr, NULL, SMC_LLC_WAIT_TIME,
-			      SMC_LLC_ADD_LINK);
-	if (!qentry) {
-		struct smc_clc_msg_decline dclc;
-
-		rc = smc_clc_wait_msg(smc, &dclc, sizeof(dclc),
-				      SMC_CLC_DECLINE, CLC_WAIT_TIME_SHORT);
-		if (rc == -EAGAIN)
-			rc = 0; /* no DECLINE received, go with one link */
-		return rc;
+	if (link->lgr->max_links > 1) {
+		/* optional 2nd link, receive ADD LINK request from server */
+		qentry = smc_llc_wait(link->lgr, NULL, SMC_LLC_WAIT_TIME,
+				      SMC_LLC_ADD_LINK);
+		if (!qentry) {
+			struct smc_clc_msg_decline dclc;
+
+			rc = smc_clc_wait_msg(smc, &dclc, sizeof(dclc),
+					      SMC_CLC_DECLINE, CLC_WAIT_TIME_SHORT);
+			if (rc == -EAGAIN)
+				rc = 0; /* no DECLINE received, go with one link */
+			return rc;
+		}
+		smc_llc_flow_qentry_clr(&link->lgr->llc_flow_lcl);
+		smc_llc_cli_add_link(link, qentry);
 	}
-	smc_llc_flow_qentry_clr(&link->lgr->llc_flow_lcl);
-	smc_llc_cli_add_link(link, qentry);
 	return 0;
 }
 
@@ -1243,6 +1245,7 @@ static int smc_connect_rdma(struct smc_sock *smc,
 	memcpy(ini->peer_gid, aclc->r0.lcl.gid, SMC_GID_SIZE);
 	memcpy(ini->peer_mac, aclc->r0.lcl.mac, ETH_ALEN);
 	ini->max_conns = SMC_CONN_PER_LGR_MAX;
+	ini->max_links = SMC_LINKS_ADD_LNK_MAX;
 
 	reason_code = smc_connect_rdma_v2_prepare(smc, aclc, ini);
 	if (reason_code)
@@ -1887,10 +1890,12 @@ static int smcr_serv_conf_first_link(struct smc_sock *smc)
 	smc_llc_link_active(link);
 	smcr_lgr_set_type(link->lgr, SMC_LGR_SINGLE);
 
-	down_write(&link->lgr->llc_conf_mutex);
-	/* initial contact - try to establish second link */
-	smc_llc_srv_add_link(link, NULL);
-	up_write(&link->lgr->llc_conf_mutex);
+	if (link->lgr->max_links > 1) {
+		down_write(&link->lgr->llc_conf_mutex);
+		/* initial contact - try to establish second link */
+		smc_llc_srv_add_link(link, NULL);
+		up_write(&link->lgr->llc_conf_mutex);
+	}
 	return 0;
 }
 
@@ -2494,6 +2499,11 @@ static void smc_listen_work(struct work_struct *work)
 		goto out_decl;
 	}
 
+	/* fce smc release version is needed in smc_listen_rdma_finish,
+	 * so save fce info here.
+	 */
+	smc_conn_save_peer_info_fce(new_smc, cclc);
+
 	/* finish worker */
 	if (!ini->is_smcd) {
 		rc = smc_listen_rdma_finish(new_smc, cclc,

net/smc/smc_clc.c

@@ -433,8 +433,10 @@ static int smc_clc_fill_fce(struct smc_clc_first_contact_ext_v2x *fce,
 	}
 
 	if (ini->release_nr >= SMC_RELEASE_1) {
-		if (!ini->is_smcd)
+		if (!ini->is_smcd) {
 			fce->max_conns = ini->max_conns;
+			fce->max_links = ini->max_links;
+		}
 	}
 
 out:
@@ -942,6 +944,7 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini)
 	if (smcr_indicated(ini->smc_type_v2)) {
 		memcpy(v2_ext->roce, ini->smcrv2.ib_gid_v2, SMC_GID_SIZE);
 		v2_ext->max_conns = SMC_CONN_PER_LGR_PREFER;
+		v2_ext->max_links = SMC_LINKS_PER_LGR_MAX_PREFER;
 	}
 
 	pclc_base->hdr.length = htons(plen);
@@ -1174,6 +1177,7 @@ int smc_clc_srv_v2x_features_validate(struct smc_clc_msg_proposal *pclc,
 	struct smc_clc_v2_extension *pclc_v2_ext;
 
 	ini->max_conns = SMC_CONN_PER_LGR_MAX;
+	ini->max_links = SMC_LINKS_ADD_LNK_MAX;
 
 	if ((!(ini->smcd_version & SMC_V2) && !(ini->smcr_version & SMC_V2)) ||
 	    ini->release_nr < SMC_RELEASE_1)
@@ -1187,6 +1191,10 @@ int smc_clc_srv_v2x_features_validate(struct smc_clc_msg_proposal *pclc,
 		ini->max_conns = min_t(u8, pclc_v2_ext->max_conns, SMC_CONN_PER_LGR_PREFER);
 		if (ini->max_conns < SMC_CONN_PER_LGR_MIN)
 			return SMC_CLC_DECL_MAXCONNERR;
+
+		ini->max_links = min_t(u8, pclc_v2_ext->max_links, SMC_LINKS_PER_LGR_MAX_PREFER);
+		if (ini->max_links < SMC_LINKS_ADD_LNK_MIN)
+			return SMC_CLC_DECL_MAXLINKERR;
 	}
 
 	return 0;
@@ -1205,6 +1213,11 @@ int smc_clc_clnt_v2x_features_validate(struct smc_clc_first_contact_ext *fce,
 		if (fce_v2x->max_conns < SMC_CONN_PER_LGR_MIN)
 			return SMC_CLC_DECL_MAXCONNERR;
 		ini->max_conns = fce_v2x->max_conns;
+
+		if (fce_v2x->max_links > SMC_LINKS_ADD_LNK_MAX ||
+		    fce_v2x->max_links < SMC_LINKS_ADD_LNK_MIN)
+			return SMC_CLC_DECL_MAXLINKERR;
+		ini->max_links = fce_v2x->max_links;
 	}
 
 	return 0;
@@ -1233,6 +1246,8 @@ int smc_clc_v2x_features_confirm_check(struct smc_clc_msg_accept_confirm *cclc,
 	if (!ini->is_smcd) {
 		if (fce_v2x->max_conns != ini->max_conns)
 			return SMC_CLC_DECL_MAXCONNERR;
+		if (fce_v2x->max_links != ini->max_links)
+			return SMC_CLC_DECL_MAXLINKERR;
 	}
 
 	return 0;

net/smc/smc_clc.h

@@ -47,6 +47,7 @@
 #define SMC_CLC_DECL_NOUEID	0x03030008  /* peer sent no UEID	      */
 #define SMC_CLC_DECL_RELEASEERR	0x03030009  /* release version negotiate failed */
 #define SMC_CLC_DECL_MAXCONNERR	0x0303000a  /* max connections negotiate failed */
+#define SMC_CLC_DECL_MAXLINKERR	0x0303000b  /* max links negotiate failed */
 #define SMC_CLC_DECL_MODEUNSUPP	0x03040000  /* smc modes do not match (R or D)*/
 #define SMC_CLC_DECL_RMBE_EC	0x03050000  /* peer has eyecatcher in RMBE    */
 #define SMC_CLC_DECL_OPTUNSUPP	0x03060000  /* fastopen sockopt not supported */
@@ -136,7 +137,8 @@ struct smc_clc_v2_extension {
 	struct smc_clnt_opts_area_hdr hdr;
 	u8 roce[16];		/* RoCEv2 GID */
 	u8 max_conns;
-	u8 reserved[15];
+	u8 max_links;
+	u8 reserved[14];
 	u8 user_eids[][SMC_MAX_EID_LEN];
 };
 
@@ -239,7 +241,8 @@ struct smc_clc_first_contact_ext {
 struct smc_clc_first_contact_ext_v2x {
 	struct smc_clc_first_contact_ext fce_v2_base;
 	u8 max_conns; /* for SMC-R only */
-	u8 reserved3[3];
+	u8 max_links; /* for SMC-R only */
+	u8 reserved3[2];
 	__be32 vendor_exp_options;
 	u8 reserved4[8];
 } __packed;		/* format defined in

net/smc/smc_core.c

@@ -896,10 +896,12 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini)
 			memcpy(lgr->nexthop_mac, ini->smcrv2.nexthop_mac,
 			       ETH_ALEN);
 			lgr->max_conns = ini->max_conns;
+			lgr->max_links = ini->max_links;
 		} else {
 			ibdev = ini->ib_dev;
 			ibport = ini->ib_port;
 			lgr->max_conns = SMC_CONN_PER_LGR_MAX;
+			lgr->max_links = SMC_LINKS_ADD_LNK_MAX;
 		}
 		memcpy(lgr->pnet_id, ibdev->pnetid[ibport - 1],
 		       SMC_MAX_PNETID_LEN);
@@ -1666,6 +1668,9 @@ void smcr_port_add(struct smc_ib_device *smcibdev, u8 ibport)
 		    !rdma_dev_access_netns(smcibdev->ibdev, lgr->net))
 			continue;
 
+		if (lgr->type == SMC_LGR_SINGLE && lgr->max_links <= 1)
+			continue;
+
 		/* trigger local add link processing */
 		link = smc_llc_usable_link(lgr);
 		if (link)

net/smc/smc_core.h

@@ -173,6 +173,15 @@ struct smc_link {
  */
 #define SMC_LINKS_PER_LGR_MAX	3
 #define SMC_SINGLE_LINK		0
+#define SMC_LINKS_ADD_LNK_MIN	1	/* min. # of links per link group */
+#define SMC_LINKS_ADD_LNK_MAX	2	/* max. # of links per link group, also is the
+					 * default value for smc-r v1.0 and v2.0
+					 */
+#define SMC_LINKS_PER_LGR_MAX_PREFER	2	/* Preferred max links per link group used for
+						 * SMC-R v2.1 and later negotiation, vendors or
+						 * distrubutions may modify it to a value between
+						 * 1-2 as needed.
+						 */
 
 /* tx/rx buffer list element for sndbufs list and rmbs list of a lgr */
 struct smc_buf_desc {
@@ -342,6 +351,8 @@ struct smc_link_group {
 			struct net		*net;
 			u8			max_conns;
 						/* max conn can be assigned to lgr */
+			u8			max_links;
+						/* max links can be added in lgr */
 		};
 		struct { /* SMC-D */
 			u64			peer_gid;
@@ -387,6 +398,7 @@ struct smc_init_info {
 	u8			smc_type_v2;
 	u8			release_nr;
 	u8			max_conns;
+	u8			max_links;
 	u8			first_contact_peer;
 	u8			first_contact_local;
 	unsigned short		vlan_id;

net/smc/smc_llc.c

@@ -59,8 +59,6 @@ struct smc_llc_msg_confirm_link {	/* type 0x01 */
 #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];
@@ -472,10 +470,12 @@ int smc_llc_send_confirm_link(struct smc_link *link,
 	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;
+	confllc->max_links = SMC_LINKS_ADD_LNK_MAX;
 	if (link->lgr->smc_version == SMC_V2 &&
-	    link->lgr->peer_smc_release >= SMC_RELEASE_1)
+	    link->lgr->peer_smc_release >= SMC_RELEASE_1) {
 		confllc->max_conns = link->lgr->max_conns;
+		confllc->max_links = link->lgr->max_links;
+	}
 	/* send llc message */
 	rc = smc_wr_tx_send(link, pend);
 put_out:
@@ -1045,6 +1045,11 @@ int smc_llc_cli_add_link(struct smc_link *link, struct smc_llc_qentry *qentry)
 		goto out_reject;
 	}
 
+	if (lgr->type == SMC_LGR_SINGLE && lgr->max_links <= 1) {
+		rc = 0;
+		goto out_reject;
+	}
+
 	ini->vlan_id = lgr->vlan_id;
 	if (lgr->smc_version == SMC_V2) {
 		ini->check_smcrv2 = true;
@@ -1169,6 +1174,9 @@ static void smc_llc_cli_add_link_invite(struct smc_link *link,
 	    lgr->type == SMC_LGR_ASYMMETRIC_PEER)
 		goto out;
 
+	if (lgr->type == SMC_LGR_SINGLE && lgr->max_links <= 1)
+		goto out;
+
 	ini = kzalloc(sizeof(*ini), GFP_KERNEL);
 	if (!ini)
 		goto out;
@@ -1414,6 +1422,11 @@ int smc_llc_srv_add_link(struct smc_link *link,
 		goto out;
 	}
 
+	if (lgr->type == SMC_LGR_SINGLE && lgr->max_links <= 1) {
+		rc = 0;
+		goto out;
+	}
+
 	/* ignore client add link recommendation, start new flow */
 	ini->vlan_id = lgr->vlan_id;
 	if (lgr->smc_version == SMC_V2) {