RDMA/core: Add an rb_tree that stores cm_ids sorted by ifindex and remote IP

Add to the cma, a tree that keeps track of all rdma_id_private channels
that were created while in RoCE mode.

The IDs are sorted first according to their netdevice ifindex then their
destination IP. And for IDs with matching IP they would be at the same node
in the tree, since the tree data is a list of all ids with matching destination IP.

The tree allows fast and efficient lookup of ids using an ifindex and
IP address which is useful for identifying relevant net_events promptly.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Patrisious Haddad <[e-mail]>
Reviewed-by: Mark Zhang <[e-mail]>
Signed-off-by: Leon Romanovsky <[e-mail]>

drivers/infiniband/core/cma.c

···
 #include <linux/in6.h>
 #include <linux/mutex.h>
 #include <linux/random.h>
+#include <linux/rbtree.h>
 #include <linux/igmp.h>
 #include <linux/xarray.h>
 #include <linux/inetdevice.h>
···
 static LIST_HEAD(dev_list);
 static LIST_HEAD(listen_any_list);
 static DEFINE_MUTEX(lock);
+static struct rb_root id_table = RB_ROOT;
+/* Serialize operations of id_table tree */
+static DEFINE_SPINLOCK(id_table_lock);
 static struct workqueue_struct *cma_wq;
 static unsigned int cma_pernet_id;
 
···
 		return NULL;
 	}
 }
+
+struct id_table_entry {
+	struct list_head id_list;
+	struct rb_node rb_node;
+};
 
 struct cma_device {
 	struct list_head	list;
···
 	return hdr->ip_version >> 4;
 }
 
-static inline void cma_set_ip_ver(struct cma_hdr *hdr, u8 ip_ver)
+static void cma_set_ip_ver(struct cma_hdr *hdr, u8 ip_ver)
 {
 	hdr->ip_version = (ip_ver << 4) | (hdr->ip_version & 0xF);
+}
+
+static struct sockaddr *cma_src_addr(struct rdma_id_private *id_priv)
+{
+	return (struct sockaddr *)&id_priv->id.route.addr.src_addr;
+}
+
+static inline struct sockaddr *cma_dst_addr(struct rdma_id_private *id_priv)
+{
+	return (struct sockaddr *)&id_priv->id.route.addr.dst_addr;
 }
 
 static int cma_igmp_send(struct net_device *ndev, union ib_gid *mgid, bool join)
···
 		rtnl_unlock();
 	}
 	return (in_dev) ? 0 : -ENODEV;
+}
+
+static int compare_netdev_and_ip(int ifindex_a, struct sockaddr *sa,
+				 struct id_table_entry *entry_b)
+{
+	struct rdma_id_private *id_priv = list_first_entry(
+		&entry_b->id_list, struct rdma_id_private, id_list_entry);
+	int ifindex_b = id_priv->id.route.addr.dev_addr.bound_dev_if;
+	struct sockaddr *sb = cma_dst_addr(id_priv);
+
+	if (ifindex_a != ifindex_b)
+		return (ifindex_a > ifindex_b) ? 1 : -1;
+
+	if (sa->sa_family != sb->sa_family)
+		return sa->sa_family - sb->sa_family;
+
+	if (sa->sa_family == AF_INET)
+		return memcmp((char *)&((struct sockaddr_in *)sa)->sin_addr,
+			      (char *)&((struct sockaddr_in *)sb)->sin_addr,
+			      sizeof(((struct sockaddr_in *)sa)->sin_addr));
+
+	return ipv6_addr_cmp(&((struct sockaddr_in6 *)sa)->sin6_addr,
+			     &((struct sockaddr_in6 *)sb)->sin6_addr);
+}
+
+static int cma_add_id_to_tree(struct rdma_id_private *node_id_priv)
+{
+	struct rb_node **new, *parent = NULL;
+	struct id_table_entry *this, *node;
+	unsigned long flags;
+	int result;
+
+	node = kzalloc(sizeof(*node), GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&id_table_lock, flags);
+	new = &id_table.rb_node;
+	while (*new) {
+		this = container_of(*new, struct id_table_entry, rb_node);
+		result = compare_netdev_and_ip(
+			node_id_priv->id.route.addr.dev_addr.bound_dev_if,
+			cma_dst_addr(node_id_priv), this);
+
+		parent = *new;
+		if (result < 0)
+			new = &((*new)->rb_left);
+		else if (result > 0)
+			new = &((*new)->rb_right);
+		else {
+			list_add_tail(&node_id_priv->id_list_entry,
+				      &this->id_list);
+			kfree(node);
+			goto unlock;
+		}
+	}
+
+	INIT_LIST_HEAD(&node->id_list);
+	list_add_tail(&node_id_priv->id_list_entry, &node->id_list);
+
+	rb_link_node(&node->rb_node, parent, new);
+	rb_insert_color(&node->rb_node, &id_table);
+
+unlock:
+	spin_unlock_irqrestore(&id_table_lock, flags);
+	return 0;
+}
+
+static struct id_table_entry *
+node_from_ndev_ip(struct rb_root *root, int ifindex, struct sockaddr *sa)
+{
+	struct rb_node *node = root->rb_node;
+	struct id_table_entry *data;
+	int result;
+
+	while (node) {
+		data = container_of(node, struct id_table_entry, rb_node);
+		result = compare_netdev_and_ip(ifindex, sa, data);
+		if (result < 0)
+			node = node->rb_left;
+		else if (result > 0)
+			node = node->rb_right;
+		else
+			return data;
+	}
+
+	return NULL;
+}
+
+static void cma_remove_id_from_tree(struct rdma_id_private *id_priv)
+{
+	struct id_table_entry *data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&id_table_lock, flags);
+	if (list_empty(&id_priv->id_list_entry))
+		goto out;
+
+	data = node_from_ndev_ip(&id_table,
+				 id_priv->id.route.addr.dev_addr.bound_dev_if,
+				 cma_dst_addr(id_priv));
+	if (!data)
+		goto out;
+
+	list_del_init(&id_priv->id_list_entry);
+	if (list_empty(&data->id_list)) {
+		rb_erase(&data->rb_node, &id_table);
+		kfree(data);
+	}
+out:
+	spin_unlock_irqrestore(&id_table_lock, flags);
 }
 
 static void _cma_attach_to_dev(struct rdma_id_private *id_priv,
···
 		id_priv->id.route.addr.dev_addr.sgid_attr = NULL;
 	}
 	mutex_unlock(&lock);
-}
-
-static inline struct sockaddr *cma_src_addr(struct rdma_id_private *id_priv)
-{
-	return (struct sockaddr *) &id_priv->id.route.addr.src_addr;
-}
-
-static inline struct sockaddr *cma_dst_addr(struct rdma_id_private *id_priv)
-{
-	return (struct sockaddr *) &id_priv->id.route.addr.dst_addr;
 }
 
 static inline unsigned short cma_family(struct rdma_id_private *id_priv)
···
 	refcount_set(&id_priv->refcount, 1);
 	mutex_init(&id_priv->handler_mutex);
 	INIT_LIST_HEAD(&id_priv->device_item);
+	INIT_LIST_HEAD(&id_priv->id_list_entry);
 	INIT_LIST_HEAD(&id_priv->listen_list);
 	INIT_LIST_HEAD(&id_priv->mc_list);
 	get_random_bytes(&id_priv->seq_num, sizeof id_priv->seq_num);
···
 	cma_cancel_operation(id_priv, state);
 
 	rdma_restrack_del(&id_priv->res);
+	cma_remove_id_from_tree(id_priv);
 	if (id_priv->cma_dev) {
 		if (rdma_cap_ib_cm(id_priv->id.device, 1)) {
 			if (id_priv->cm_id.ib)
···
 	cma_id_get(id_priv);
 	if (rdma_cap_ib_sa(id->device, id->port_num))
 		ret = cma_resolve_ib_route(id_priv, timeout_ms);
-	else if (rdma_protocol_roce(id->device, id->port_num))
+	else if (rdma_protocol_roce(id->device, id->port_num)) {
 		ret = cma_resolve_iboe_route(id_priv);
+		if (!ret)
+			cma_add_id_to_tree(id_priv);
+	}
 	else if (rdma_protocol_iwarp(id->device, id->port_num))
 		ret = cma_resolve_iw_route(id_priv);
 	else

drivers/infiniband/core/cma_priv.h

···
 		struct list_head listen_item;
 		struct list_head listen_list;
 	};
+	struct list_head        id_list_entry;
 	struct cma_device	*cma_dev;
 	struct list_head	mc_list;