net: dsa: create a dsa_lag structure

The main purpose of this change is to create a data structure for a LAG
as seen by DSA. This is similar to what we have for bridging - we pass a
copy of this structure by value to ->port_lag_join and ->port_lag_leave.
For now we keep the lag_dev, id and a reference count in it. Future
patches will add a list of FDB entries for the LAG (these also need to
be refcounted to work properly).

The LAG structure is created using dsa_port_lag_create() and destroyed
using dsa_port_lag_destroy(), just like we have for bridging.

Because now, the dsa_lag itself is refcounted, we can simplify
dsa_lag_map() and dsa_lag_unmap(). These functions need to keep a LAG in
the dst->lags array only as long as at least one port uses it. The
refcounting logic inside those functions can be removed now - they are
called only when we should perform the operation.

dsa_lag_dev() is renamed to dsa_lag_by_id() and now returns the dsa_lag
structure instead of the lag_dev net_device.

dsa_lag_foreach_port() now takes the dsa_lag structure as argument.

dst->lags holds an array of dsa_lag structures.

dsa_lag_map() now also saves the dsa_lag->id value, so that linear
walking of dst->lags in drivers using dsa_lag_id() is no longer
necessary. They can just look at lag.id.

dsa_port_lag_id_get() is a helper, similar to dsa_port_bridge_num_get(),
which can be used by drivers to get the LAG ID assigned by DSA to a
given port.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 23 insertions, 18 deletions

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 4915abe0d4d2..030d5f26715a 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -72,27 +72,24 @@ int dsa_broadcast(unsigned long e, void *v)
 }
 
 /**
- * dsa_lag_map() - Map LAG netdev to a linear LAG ID
+ * dsa_lag_map() - Map LAG structure to a linear LAG array
  * @dst: Tree in which to record the mapping.
- * @lag_dev: Netdev that is to be mapped to an ID.
+ * @lag: LAG structure that is to be mapped to the tree's array.
  *
- * dsa_lag_id/dsa_lag_dev can then be used to translate between the
+ * dsa_lag_id/dsa_lag_by_id can then be used to translate between the
  * two spaces. The size of the mapping space is determined by the
  * driver by setting ds->num_lag_ids. It is perfectly legal to leave
  * it unset if it is not needed, in which case these functions become
  * no-ops.
  */
-void dsa_lag_map(struct dsa_switch_tree *dst, struct net_device *lag_dev)
+void dsa_lag_map(struct dsa_switch_tree *dst, struct dsa_lag *lag)
 {
 	unsigned int id;
 
-	if (dsa_lag_id(dst, lag_dev) > 0)
-		/* Already mapped */
-		return;
-
 	for (id = 1; id <= dst->lags_len; id++) {
-		if (!dsa_lag_dev(dst, id)) {
-			dst->lags[id - 1] = lag_dev;
+		if (!dsa_lag_by_id(dst, id)) {
+			dst->lags[id - 1] = lag;
+			lag->id = id;
 			return;
 		}
 	}
@@ -108,28 +105,36 @@ void dsa_lag_map(struct dsa_switch_tree *dst, struct net_device *lag_dev)
 /**
  * dsa_lag_unmap() - Remove a LAG ID mapping
  * @dst: Tree in which the mapping is recorded.
- * @lag_dev: Netdev that was mapped.
+ * @lag: LAG structure that was mapped.
  *
  * As there may be multiple users of the mapping, it is only removed
  * if there are no other references to it.
  */
-void dsa_lag_unmap(struct dsa_switch_tree *dst, struct net_device *lag_dev)
+void dsa_lag_unmap(struct dsa_switch_tree *dst, struct dsa_lag *lag)
 {
-	struct dsa_port *dp;
 	unsigned int id;
 
-	dsa_lag_foreach_port(dp, dst, lag_dev)
-		/* There are remaining users of this mapping */
-		return;
-
 	dsa_lags_foreach_id(id, dst) {
-		if (dsa_lag_dev(dst, id) == lag_dev) {
+		if (dsa_lag_by_id(dst, id) == lag) {
 			dst->lags[id - 1] = NULL;
+			lag->id = 0;
 			break;
 		}
 	}
 }
 
+struct dsa_lag *dsa_tree_lag_find(struct dsa_switch_tree *dst,
+				  const struct net_device *lag_dev)
+{
+	struct dsa_port *dp;
+
+	list_for_each_entry(dp, &dst->ports, list)
+		if (dsa_port_lag_dev_get(dp) == lag_dev)
+			return dp->lag;
+
+	return NULL;
+}
+
 struct dsa_bridge *dsa_tree_bridge_find(struct dsa_switch_tree *dst,
 					const struct net_device *br)
 {