net/smc: support max connections per lgr negotiation

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

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

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

     Confirm(max conns(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>

net/smc/af_smc.c

@@ -1242,6 +1242,7 @@ static int smc_connect_rdma(struct smc_sock *smc,
 	memcpy(ini->peer_systemid, aclc->r0.lcl.id_for_peer, SMC_SYSTEMID_LEN);
 	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;
 
 	reason_code = smc_connect_rdma_v2_prepare(smc, aclc, ini);
 	if (reason_code)

net/smc/smc_clc.c

@@ -427,9 +427,17 @@ static int smc_clc_fill_fce(struct smc_clc_first_contact_ext_v2x *fce,
 	fce->fce_v2_base.os_type = SMC_CLC_OS_LINUX;
 	fce->fce_v2_base.release = ini->release_nr;
 	memcpy(fce->fce_v2_base.hostname, smc_hostname, sizeof(smc_hostname));
-	if (ini->is_smcd && ini->release_nr < SMC_RELEASE_1)
+	if (ini->is_smcd && ini->release_nr < SMC_RELEASE_1) {
 		ret = sizeof(struct smc_clc_first_contact_ext);
+		goto out;
+	}
+
+	if (ini->release_nr >= SMC_RELEASE_1) {
+		if (!ini->is_smcd)
+			fce->max_conns = ini->max_conns;
+	}
 
+out:
 	return ret;
 }
 
@@ -931,8 +939,10 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini)
 				sizeof(struct smc_clc_smcd_gid_chid);
 		}
 	}
-	if (smcr_indicated(ini->smc_type_v2))
+	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;
+	}
 
 	pclc_base->hdr.length = htons(plen);
 	memcpy(trl->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
@@ -1163,6 +1173,8 @@ 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;
+
 	if ((!(ini->smcd_version & SMC_V2) && !(ini->smcr_version & SMC_V2)) ||
 	    ini->release_nr < SMC_RELEASE_1)
 		return 0;
@@ -1171,15 +1183,30 @@ int smc_clc_srv_v2x_features_validate(struct smc_clc_msg_proposal *pclc,
 	if (!pclc_v2_ext)
 		return SMC_CLC_DECL_NOV2EXT;
 
+	if (ini->smcr_version & SMC_V2) {
+		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;
+	}
+
 	return 0;
 }
 
 int smc_clc_clnt_v2x_features_validate(struct smc_clc_first_contact_ext *fce,
 				       struct smc_init_info *ini)
 {
+	struct smc_clc_first_contact_ext_v2x *fce_v2x =
+		(struct smc_clc_first_contact_ext_v2x *)fce;
+
 	if (ini->release_nr < SMC_RELEASE_1)
 		return 0;
 
+	if (!ini->is_smcd) {
+		if (fce_v2x->max_conns < SMC_CONN_PER_LGR_MIN)
+			return SMC_CLC_DECL_MAXCONNERR;
+		ini->max_conns = fce_v2x->max_conns;
+	}
+
 	return 0;
 }
 
@@ -1190,6 +1217,8 @@ int smc_clc_v2x_features_confirm_check(struct smc_clc_msg_accept_confirm *cclc,
 		(struct smc_clc_msg_accept_confirm_v2 *)cclc;
 	struct smc_clc_first_contact_ext *fce =
 		smc_get_clc_first_contact_ext(clc_v2, ini->is_smcd);
+	struct smc_clc_first_contact_ext_v2x *fce_v2x =
+		(struct smc_clc_first_contact_ext_v2x *)fce;
 
 	if (cclc->hdr.version == SMC_V1 ||
 	    !(cclc->hdr.typev2 & SMC_FIRST_CONTACT_MASK))
@@ -1201,6 +1230,11 @@ int smc_clc_v2x_features_confirm_check(struct smc_clc_msg_accept_confirm *cclc,
 	if (fce->release < SMC_RELEASE_1)
 		return 0;
 
+	if (!ini->is_smcd) {
+		if (fce_v2x->max_conns != ini->max_conns)
+			return SMC_CLC_DECL_MAXCONNERR;
+	}
+
 	return 0;
 }
 

net/smc/smc_clc.h

@@ -46,6 +46,7 @@
 #define SMC_CLC_DECL_NOSMCD2DEV	0x03030007  /* no SMC-Dv2 device found	      */
 #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_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 */
@@ -134,7 +135,8 @@ struct smc_clc_smcd_gid_chid {
 struct smc_clc_v2_extension {
 	struct smc_clnt_opts_area_hdr hdr;
 	u8 roce[16];		/* RoCEv2 GID */
-	u8 reserved[16];
+	u8 max_conns;
+	u8 reserved[15];
 	u8 user_eids[][SMC_MAX_EID_LEN];
 };
 
@@ -236,7 +238,8 @@ struct smc_clc_first_contact_ext {
 
 struct smc_clc_first_contact_ext_v2x {
 	struct smc_clc_first_contact_ext fce_v2_base;
-	u8 reserved3[4];
+	u8 max_conns; /* for SMC-R only */
+	u8 reserved3[3];
 	__be32 vendor_exp_options;
 	u8 reserved4[8];
 } __packed;		/* format defined in

net/smc/smc_core.c

@@ -895,9 +895,11 @@ static int smc_lgr_create(struct smc_sock *smc, struct smc_init_info *ini)
 			lgr->uses_gateway = ini->smcrv2.uses_gateway;
 			memcpy(lgr->nexthop_mac, ini->smcrv2.nexthop_mac,
 			       ETH_ALEN);
+			lgr->max_conns = ini->max_conns;
 		} else {
 			ibdev = ini->ib_dev;
 			ibport = ini->ib_port;
+			lgr->max_conns = SMC_CONN_PER_LGR_MAX;
 		}
 		memcpy(lgr->pnet_id, ibdev->pnetid[ibport - 1],
 		       SMC_MAX_PNETID_LEN);
@@ -1888,7 +1890,7 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini)
 		    (ini->smcd_version == SMC_V2 ||
 		     lgr->vlan_id == ini->vlan_id) &&
 		    (role == SMC_CLNT || ini->is_smcd ||
-		    (lgr->conns_num < SMC_RMBS_PER_LGR_MAX &&
+		    (lgr->conns_num < lgr->max_conns &&
 		      !bitmap_full(lgr->rtokens_used_mask, SMC_RMBS_PER_LGR_MAX)))) {
 			/* link group found */
 			ini->first_contact_local = 0;

net/smc/smc_core.h

@@ -22,6 +22,15 @@
 #include "smc_ib.h"
 
 #define SMC_RMBS_PER_LGR_MAX	255	/* max. # of RMBs per link group */
+#define SMC_CONN_PER_LGR_MIN	16	/* min. # of connections per link group */
+#define SMC_CONN_PER_LGR_MAX	255	/* max. # of connections per link group,
+					 * also is the default value for SMC-R v1 and v2.0
+					 */
+#define SMC_CONN_PER_LGR_PREFER	255	/* Preferred connections per link group used for
+					 * SMC-R v2.1 and later negotiation, vendors or
+					 * distrubutions may modify it to a value between
+					 * 16-255 as needed.
+					 */
 
 struct smc_lgr_list {			/* list of link group definition */
 	struct list_head	list;
@@ -331,6 +340,8 @@ struct smc_link_group {
 			__be32			saddr;
 						/* net namespace */
 			struct net		*net;
+			u8			max_conns;
+						/* max conn can be assigned to lgr */
 		};
 		struct { /* SMC-D */
 			u64			peer_gid;
@@ -375,6 +386,7 @@ struct smc_init_info {
 	u8			smc_type_v1;
 	u8			smc_type_v2;
 	u8			release_nr;
+	u8			max_conns;
 	u8			first_contact_peer;
 	u8			first_contact_local;
 	unsigned short		vlan_id;

net/smc/smc_llc.c

@@ -52,7 +52,8 @@ struct smc_llc_msg_confirm_link {	/* type 0x01 */
 	u8 link_num;
 	u8 link_uid[SMC_LGR_ID_SIZE];
 	u8 max_links;
-	u8 reserved[9];
+	u8 max_conns;
+	u8 reserved[8];
 };
 
 #define SMC_LLC_FLAG_ADD_LNK_REJ	0x40
@@ -472,6 +473,9 @@ int smc_llc_send_confirm_link(struct smc_link *link,
 	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;
+	if (link->lgr->smc_version == SMC_V2 &&
+	    link->lgr->peer_smc_release >= SMC_RELEASE_1)
+		confllc->max_conns = link->lgr->max_conns;
 	/* send llc message */
 	rc = smc_wr_tx_send(link, pend);
 put_out: