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, 3 insertions, 1 deletions

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);