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>

6 files changed, 87 insertions, 40 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)
 {
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 0293a749b3ac..8612ff8ea7fe 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -76,7 +76,7 @@ struct dsa_notifier_mdb_info {
 
 /* DSA_NOTIFIER_LAG_* */
 struct dsa_notifier_lag_info {
-	struct net_device *lag_dev;
+	struct dsa_lag lag;
 	int sw_index;
 	int port;
 
@@ -487,8 +487,10 @@ int dsa_switch_register_notifier(struct dsa_switch *ds);
 void dsa_switch_unregister_notifier(struct dsa_switch *ds);
 
 /* dsa2.c */
-void dsa_lag_map(struct dsa_switch_tree *dst, struct net_device *lag_dev);
-void dsa_lag_unmap(struct dsa_switch_tree *dst, struct net_device *lag_dev);
+void dsa_lag_map(struct dsa_switch_tree *dst, struct dsa_lag *lag);
+void dsa_lag_unmap(struct dsa_switch_tree *dst, struct dsa_lag *lag);
+struct dsa_lag *dsa_tree_lag_find(struct dsa_switch_tree *dst,
+				  const struct net_device *lag_dev);
 int dsa_tree_notify(struct dsa_switch_tree *dst, unsigned long e, void *v);
 int dsa_broadcast(unsigned long e, void *v);
 int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst,
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 0b42b3693e49..338467c1adbb 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -429,7 +429,7 @@ int dsa_port_lag_change(struct dsa_port *dp,
 	};
 	bool tx_enabled;
 
-	if (!dp->lag_dev)
+	if (!dp->lag)
 		return 0;
 
 	/* On statically configured aggregates (e.g. loadbalance
@@ -447,6 +447,45 @@ int dsa_port_lag_change(struct dsa_port *dp,
 	return dsa_port_notify(dp, DSA_NOTIFIER_LAG_CHANGE, &info);
 }
 
+static int dsa_port_lag_create(struct dsa_port *dp,
+			       struct net_device *lag_dev)
+{
+	struct dsa_switch *ds = dp->ds;
+	struct dsa_lag *lag;
+
+	lag = dsa_tree_lag_find(ds->dst, lag_dev);
+	if (lag) {
+		refcount_inc(&lag->refcount);
+		dp->lag = lag;
+		return 0;
+	}
+
+	lag = kzalloc(sizeof(*lag), GFP_KERNEL);
+	if (!lag)
+		return -ENOMEM;
+
+	refcount_set(&lag->refcount, 1);
+	lag->dev = lag_dev;
+	dsa_lag_map(ds->dst, lag);
+	dp->lag = lag;
+
+	return 0;
+}
+
+static void dsa_port_lag_destroy(struct dsa_port *dp)
+{
+	struct dsa_lag *lag = dp->lag;
+
+	dp->lag = NULL;
+	dp->lag_tx_enabled = false;
+
+	if (!refcount_dec_and_test(&lag->refcount))
+		return;
+
+	dsa_lag_unmap(dp->ds->dst, lag);
+	kfree(lag);
+}
+
 int dsa_port_lag_join(struct dsa_port *dp, struct net_device *lag_dev,
 		      struct netdev_lag_upper_info *uinfo,
 		      struct netlink_ext_ack *extack)
@@ -454,15 +493,16 @@ int dsa_port_lag_join(struct dsa_port *dp, struct net_device *lag_dev,
 	struct dsa_notifier_lag_info info = {
 		.sw_index = dp->ds->index,
 		.port = dp->index,
-		.lag_dev = lag_dev,
 		.info = uinfo,
 	};
 	struct net_device *bridge_dev;
 	int err;
 
-	dsa_lag_map(dp->ds->dst, lag_dev);
-	dp->lag_dev = lag_dev;
+	err = dsa_port_lag_create(dp, lag_dev);
+	if (err)
+		goto err_lag_create;
 
+	info.lag = *dp->lag;
 	err = dsa_port_notify(dp, DSA_NOTIFIER_LAG_JOIN, &info);
 	if (err)
 		goto err_lag_join;
@@ -480,8 +520,8 @@ int dsa_port_lag_join(struct dsa_port *dp, struct net_device *lag_dev,
 err_bridge_join:
 	dsa_port_notify(dp, DSA_NOTIFIER_LAG_LEAVE, &info);
 err_lag_join:
-	dp->lag_dev = NULL;
-	dsa_lag_unmap(dp->ds->dst, lag_dev);
+	dsa_port_lag_destroy(dp);
+err_lag_create:
 	return err;
 }
 
@@ -499,11 +539,10 @@ void dsa_port_lag_leave(struct dsa_port *dp, struct net_device *lag_dev)
 	struct dsa_notifier_lag_info info = {
 		.sw_index = dp->ds->index,
 		.port = dp->index,
-		.lag_dev = lag_dev,
 	};
 	int err;
 
-	if (!dp->lag_dev)
+	if (!dp->lag)
 		return;
 
 	/* Port might have been part of a LAG that in turn was
@@ -512,16 +551,15 @@ void dsa_port_lag_leave(struct dsa_port *dp, struct net_device *lag_dev)
 	if (br)
 		dsa_port_bridge_leave(dp, br);
 
-	dp->lag_tx_enabled = false;
-	dp->lag_dev = NULL;
+	info.lag = *dp->lag;
+
+	dsa_port_lag_destroy(dp);
 
 	err = dsa_port_notify(dp, DSA_NOTIFIER_LAG_LEAVE, &info);
 	if (err)
 		dev_err(dp->ds->dev,
 			"port %d failed to notify DSA_NOTIFIER_LAG_LEAVE: %pe\n",
 			dp->index, ERR_PTR(err));
-
-	dsa_lag_unmap(dp->ds->dst, lag_dev);
 }
 
 /* Must be called under rcu_read_lock() */
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index f61e6b72ffbb..e31c7710fee9 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -2134,7 +2134,7 @@ dsa_slave_lag_changeupper(struct net_device *dev,
 			continue;
 
 		dp = dsa_slave_to_port(lower);
-		if (!dp->lag_dev)
+		if (!dp->lag)
 			/* Software LAG */
 			continue;
 
@@ -2163,7 +2163,7 @@ dsa_slave_lag_prechangeupper(struct net_device *dev,
 			continue;
 
 		dp = dsa_slave_to_port(lower);
-		if (!dp->lag_dev)
+		if (!dp->lag)
 			/* Software LAG */
 			continue;
 
diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index c71bade9269e..0bb3987bd4e6 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -468,12 +468,12 @@ static int dsa_switch_lag_join(struct dsa_switch *ds,
 			       struct dsa_notifier_lag_info *info)
 {
 	if (ds->index == info->sw_index && ds->ops->port_lag_join)
-		return ds->ops->port_lag_join(ds, info->port, info->lag_dev,
+		return ds->ops->port_lag_join(ds, info->port, info->lag,
 					      info->info);
 
 	if (ds->index != info->sw_index && ds->ops->crosschip_lag_join)
 		return ds->ops->crosschip_lag_join(ds, info->sw_index,
-						   info->port, info->lag_dev,
+						   info->port, info->lag,
 						   info->info);
 
 	return -EOPNOTSUPP;
@@ -483,11 +483,11 @@ static int dsa_switch_lag_leave(struct dsa_switch *ds,
 				struct dsa_notifier_lag_info *info)
 {
 	if (ds->index == info->sw_index && ds->ops->port_lag_leave)
-		return ds->ops->port_lag_leave(ds, info->port, info->lag_dev);
+		return ds->ops->port_lag_leave(ds, info->port, info->lag);
 
 	if (ds->index != info->sw_index && ds->ops->crosschip_lag_leave)
 		return ds->ops->crosschip_lag_leave(ds, info->sw_index,
-						    info->port, info->lag_dev);
+						    info->port, info->lag);
 
 	return -EOPNOTSUPP;
 }
diff --git a/net/dsa/tag_dsa.c b/net/dsa/tag_dsa.c
index 26435bc4a098..c8b4bbd46191 100644
--- a/net/dsa/tag_dsa.c
+++ b/net/dsa/tag_dsa.c
@@ -246,12 +246,14 @@ static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
 
 	if (trunk) {
 		struct dsa_port *cpu_dp = dev->dsa_ptr;
+		struct dsa_lag *lag;
 
 		/* The exact source port is not available in the tag,
 		 * so we inject the frame directly on the upper
 		 * team/bond.
 		 */
-		skb->dev = dsa_lag_dev(cpu_dp->dst, source_port + 1);
+		lag = dsa_lag_by_id(cpu_dp->dst, source_port + 1);
+		skb->dev = lag ? lag->dev : NULL;
 	} else {
 		skb->dev = dsa_master_find_slave(dev, source_device,
 						 source_port);