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, 50 insertions, 12 deletions

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() */