net/smc: Introduce SMCR get linkgroup command

Introduce get linkgroup command which loops through
all available SMCR linkgroups. It uses the SMC-R linkgroup
list as entry point, not the socket list, which makes
linkgroup diagnosis possible, in case linkgroup does not
contain active connections anymore.
Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/smc.h

@@ -40,12 +40,14 @@ enum {				/* SMC PNET Table commands */
 /* SMC_GENL_FAMILY commands */
 enum {
 	SMC_NETLINK_GET_SYS_INFO = 1,
+	SMC_NETLINK_GET_LGR_SMCR,
 };
 
 /* SMC_GENL_FAMILY top level attributes */
 enum {
 	SMC_GEN_UNSPEC,
 	SMC_GEN_SYS_INFO,		/* nest */
+	SMC_GEN_LGR_SMCR,		/* nest */
 	__SMC_GEN_MAX,
 	SMC_GEN_MAX = __SMC_GEN_MAX - 1
 };
@@ -62,4 +64,17 @@ enum {
 	SMC_NLA_SYS_MAX = __SMC_NLA_SYS_MAX - 1
 };
 
+/* SMC_GEN_LGR_SMCR attributes */
+enum {
+	SMC_NLA_LGR_R_UNSPEC,
+	SMC_NLA_LGR_R_ID,		/* u32 */
+	SMC_NLA_LGR_R_ROLE,		/* u8 */
+	SMC_NLA_LGR_R_TYPE,		/* u8 */
+	SMC_NLA_LGR_R_PNETID,		/* string */
+	SMC_NLA_LGR_R_VLAN_ID,		/* u8 */
+	SMC_NLA_LGR_R_CONNS_NUM,	/* u32 */
+	__SMC_NLA_LGR_R_MAX,
+	SMC_NLA_LGR_R_MAX = __SMC_NLA_LGR_R_MAX - 1
+};
+
 #endif /* _UAPI_LINUX_SMC_H */

net/smc/smc_core.c

@@ -274,6 +274,91 @@ int smc_nl_get_sys_info(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
+static int smc_nl_fill_lgr(struct smc_link_group *lgr,
+			   struct sk_buff *skb,
+			   struct netlink_callback *cb)
+{
+	char smc_target[SMC_MAX_PNETID_LEN + 1];
+	struct nlattr *attrs;
+
+	attrs = nla_nest_start(skb, SMC_GEN_LGR_SMCR);
+	if (!attrs)
+		goto errout;
+
+	if (nla_put_u32(skb, SMC_NLA_LGR_R_ID, *((u32 *)&lgr->id)))
+		goto errattr;
+	if (nla_put_u32(skb, SMC_NLA_LGR_R_CONNS_NUM, lgr->conns_num))
+		goto errattr;
+	if (nla_put_u8(skb, SMC_NLA_LGR_R_ROLE, lgr->role))
+		goto errattr;
+	if (nla_put_u8(skb, SMC_NLA_LGR_R_TYPE, lgr->type))
+		goto errattr;
+	if (nla_put_u8(skb, SMC_NLA_LGR_R_VLAN_ID, lgr->vlan_id))
+		goto errattr;
+	snprintf(smc_target, sizeof(smc_target), "%s", lgr->pnet_id);
+	if (nla_put_string(skb, SMC_NLA_LGR_R_PNETID, smc_target))
+		goto errattr;
+
+	nla_nest_end(skb, attrs);
+	return 0;
+errattr:
+	nla_nest_cancel(skb, attrs);
+errout:
+	return -EMSGSIZE;
+}
+
+static int smc_nl_handle_lgr(struct smc_link_group *lgr,
+			     struct sk_buff *skb,
+			     struct netlink_callback *cb)
+{
+	void *nlh;
+
+	nlh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
+			  &smc_gen_nl_family, NLM_F_MULTI,
+			  SMC_NETLINK_GET_LGR_SMCR);
+	if (!nlh)
+		goto errmsg;
+	if (smc_nl_fill_lgr(lgr, skb, cb))
+		goto errout;
+
+	genlmsg_end(skb, nlh);
+	return 0;
+
+errout:
+	genlmsg_cancel(skb, nlh);
+errmsg:
+	return -EMSGSIZE;
+}
+
+static void smc_nl_fill_lgr_list(struct smc_lgr_list *smc_lgr,
+				 struct sk_buff *skb,
+				 struct netlink_callback *cb)
+{
+	struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
+	struct smc_link_group *lgr;
+	int snum = cb_ctx->pos[0];
+	int num = 0;
+
+	spin_lock_bh(&smc_lgr->lock);
+	list_for_each_entry(lgr, &smc_lgr->list, list) {
+		if (num < snum)
+			goto next;
+		if (smc_nl_handle_lgr(lgr, skb, cb))
+			goto errout;
+next:
+		num++;
+	}
+errout:
+	spin_unlock_bh(&smc_lgr->lock);
+	cb_ctx->pos[0] = num;
+}
+
+int smcr_nl_get_lgr(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	smc_nl_fill_lgr_list(&smc_lgr_list, skb, cb);
+	return skb->len;
+}
+
 void smc_lgr_cleanup_early(struct smc_connection *conn)
 {
 	struct smc_link_group *lgr = conn->lgr;

net/smc/smc_core.h

@@ -415,6 +415,7 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
 void smcr_link_down_cond(struct smc_link *lnk);
 void smcr_link_down_cond_sched(struct smc_link *lnk);
 int smc_nl_get_sys_info(struct sk_buff *skb, struct netlink_callback *cb);
+int smcr_nl_get_lgr(struct sk_buff *skb, struct netlink_callback *cb);
 
 static inline struct smc_link_group *smc_get_lgr(struct smc_link *link)
 {

net/smc/smc_netlink.c

@@ -28,6 +28,11 @@ static const struct genl_ops smc_gen_nl_ops[] = {
 		/* can be retrieved by unprivileged users */
 		.dumpit = smc_nl_get_sys_info,
 	},
+	{
+		.cmd = SMC_NETLINK_GET_LGR_SMCR,
+		/* can be retrieved by unprivileged users */
+		.dumpit = smcr_nl_get_lgr,
+	},
 };
 
 static const struct nla_policy smc_gen_nl_policy[2] = {