net: dcb: add new rewrite table

Add new rewrite table and all the required functions, offload hooks and
bookkeeping for maintaining it. The rewrite table reuses the app struct,
and the entire set of app selectors. As such, some bookeeping code can
be shared between the rewrite- and the APP table.

New functions for getting, setting and deleting entries has been added.
Apart from operating on the rewrite list, these functions do not emit a
DCB_APP_EVENT when the list os modified. The new dcb_getrewr does a
lookup based on selector and priority and returns the protocol, so that
mappings from priority to protocol, for a given selector and ifindex is
obtained.

Also, a new nested attribute has been added, that encapsulates one or
more app structs. This attribute is used to distinguish the two tables.

The dcb_lock used for the APP table is reused for the rewrite table.

Signed-off-by: Daniel Machon <[e-mail]>
Reviewed-by: Petr Machata <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/dcbnl.h

···
 	u8	dcbx;
 };
 
+u16 dcb_getrewr(struct net_device *dev, struct dcb_app *app);
+int dcb_setrewr(struct net_device *dev, struct dcb_app *app);
+int dcb_delrewr(struct net_device *dev, struct dcb_app *app);
+
 int dcb_setapp(struct net_device *, struct dcb_app *);
 u8 dcb_getapp(struct net_device *, struct dcb_app *);
 int dcb_ieee_setapp(struct net_device *, struct dcb_app *);
···
 	/* apptrust */
 	int (*dcbnl_setapptrust)(struct net_device *, u8 *, int);
 	int (*dcbnl_getapptrust)(struct net_device *, u8 *, int *);
+
+	/* rewrite */
+	int (*dcbnl_setrewr)(struct net_device *dev, struct dcb_app *app);
+	int (*dcbnl_delrewr)(struct net_device *dev, struct dcb_app *app);
 };
 
 #endif /* __NET_DCBNL_H__ */

include/uapi/linux/dcbnl.h

···
  * @DCB_ATTR_IEEE_PEER_PFC: peer PFC configuration - get only
  * @DCB_ATTR_IEEE_PEER_APP: peer APP tlv - get only
  * @DCB_ATTR_DCB_APP_TRUST_TABLE: selector trust table
+ * @DCB_ATTR_DCB_REWR_TABLE: rewrite configuration
  */
 enum ieee_attrs {
 	DCB_ATTR_IEEE_UNSPEC,
···
 	DCB_ATTR_IEEE_QCN_STATS,
 	DCB_ATTR_DCB_BUFFER,
 	DCB_ATTR_DCB_APP_TRUST_TABLE,
+	DCB_ATTR_DCB_REWR_TABLE,
 	__DCB_ATTR_IEEE_MAX
 };
 #define DCB_ATTR_IEEE_MAX (__DCB_ATTR_IEEE_MAX - 1)

net/dcb/dcbnl.c

···
 };
 
 static LIST_HEAD(dcb_app_list);
+static LIST_HEAD(dcb_rewr_list);
 static DEFINE_SPINLOCK(dcb_lock);
 
 static enum ieee_attrs_app dcbnl_app_attr_type_get(u8 selector)
···
 static int dcbnl_ieee_fill(struct sk_buff *skb, struct net_device *netdev)
 {
 	const struct dcbnl_rtnl_ops *ops = netdev->dcbnl_ops;
-	struct nlattr *ieee, *app;
+	struct nlattr *ieee, *app, *rewr;
 	struct dcb_app_type *itr;
 	int dcbx;
 	int err;
···
 
 	spin_unlock_bh(&dcb_lock);
 	nla_nest_end(skb, app);
+
+	rewr = nla_nest_start(skb, DCB_ATTR_DCB_REWR_TABLE);
+	if (!rewr)
+		return -EMSGSIZE;
+
+	spin_lock_bh(&dcb_lock);
+	list_for_each_entry(itr, &dcb_rewr_list, list) {
+		if (itr->ifindex == netdev->ifindex) {
+			enum ieee_attrs_app type =
+				dcbnl_app_attr_type_get(itr->app.selector);
+			err = nla_put(skb, type, sizeof(itr->app), &itr->app);
+			if (err) {
+				spin_unlock_bh(&dcb_lock);
+				nla_nest_cancel(skb, rewr);
+				return -EMSGSIZE;
+			}
+		}
+	}
+
+	spin_unlock_bh(&dcb_lock);
+	nla_nest_end(skb, rewr);
 
 	if (ops->dcbnl_getapptrust) {
 		err = dcbnl_getapptrust(netdev, skb);
···
 			goto err;
 	}
 
+	if (ieee[DCB_ATTR_DCB_REWR_TABLE]) {
+		err = dcbnl_app_table_setdel(ieee[DCB_ATTR_DCB_REWR_TABLE],
+					     netdev,
+					     ops->dcbnl_setrewr ?: dcb_setrewr);
+		if (err)
+			goto err;
+	}
+
 	if (ieee[DCB_ATTR_IEEE_APP_TABLE]) {
 		err = dcbnl_app_table_setdel(ieee[DCB_ATTR_IEEE_APP_TABLE],
 					     netdev, ops->ieee_setapp ?:
···
 		err = dcbnl_app_table_setdel(ieee[DCB_ATTR_IEEE_APP_TABLE],
 					     netdev, ops->ieee_delapp ?:
 					     dcb_ieee_delapp);
+		if (err)
+			goto err;
+	}
+
+	if (ieee[DCB_ATTR_DCB_REWR_TABLE]) {
+		err = dcbnl_app_table_setdel(ieee[DCB_ATTR_DCB_REWR_TABLE],
+					     netdev,
+					     ops->dcbnl_delrewr ?: dcb_delrewr);
 		if (err)
 			goto err;
 	}
···
 	return ret;
 }
 
+static struct dcb_app_type *dcb_rewr_lookup(const struct dcb_app *app,
+					    int ifindex, int proto)
+{
+	struct dcb_app_type *itr;
+
+	list_for_each_entry(itr, &dcb_rewr_list, list) {
+		if (itr->app.selector == app->selector &&
+		    itr->app.priority == app->priority &&
+		    itr->ifindex == ifindex &&
+		    ((proto == -1) || itr->app.protocol == proto))
+			return itr;
+	}
+
+	return NULL;
+}
+
 static struct dcb_app_type *dcb_app_lookup(const struct dcb_app *app,
 					   int ifindex, int prio)
 {
···
 	return prio;
 }
 EXPORT_SYMBOL(dcb_ieee_getapp_mask);
+
+/* Get protocol value from rewrite entry. */
+u16 dcb_getrewr(struct net_device *dev, struct dcb_app *app)
+{
+	struct dcb_app_type *itr;
+	u16 proto = 0;
+
+	spin_lock_bh(&dcb_lock);
+	itr = dcb_rewr_lookup(app, dev->ifindex, -1);
+	if (itr)
+		proto = itr->app.protocol;
+	spin_unlock_bh(&dcb_lock);
+
+	return proto;
+}
+EXPORT_SYMBOL(dcb_getrewr);
+
+ /* Add rewrite entry to the rewrite list. */
+int dcb_setrewr(struct net_device *dev, struct dcb_app *new)
+{
+	int err;
+
+	spin_lock_bh(&dcb_lock);
+	/* Search for existing match and abort if found. */
+	if (dcb_rewr_lookup(new, dev->ifindex, new->protocol)) {
+		err = -EEXIST;
+		goto out;
+	}
+
+	err = dcb_app_add(&dcb_rewr_list, new, dev->ifindex);
+out:
+	spin_unlock_bh(&dcb_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(dcb_setrewr);
+
+/* Delete rewrite entry from the rewrite list. */
+int dcb_delrewr(struct net_device *dev, struct dcb_app *del)
+{
+	struct dcb_app_type *itr;
+	int err = -ENOENT;
+
+	spin_lock_bh(&dcb_lock);
+	/* Search for existing match and remove it. */
+	itr = dcb_rewr_lookup(del, dev->ifindex, del->protocol);
+	if (itr) {
+		list_del(&itr->list);
+		kfree(itr);
+		err = 0;
+	}
+
+	spin_unlock_bh(&dcb_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(dcb_delrewr);
 
 /**
  * dcb_ieee_setapp - add IEEE dcb application data to app list