Vladimir Oltean acd8df5880 net: switchdev: avoid infinite recursion from LAG to bridge with port object handler ... The logic from switchdev_handle_port_obj_add_foreign() is directly adapted from switchdev_handle_fdb_event_to_device(), which already detects events on foreign interfaces and reoffloads them towards the switchdev neighbors. However, when we have a simple br0 <-> bond0 <-> swp0 topology and the switchdev_handle_port_obj_add_foreign() gets called on bond0, we get stuck into an infinite recursion: 1. bond0 does not pass check_cb(), so we attempt to find switchdev neighbor interfaces. For that, we recursively call __switchdev_handle_port_obj_add() for bond0's bridge, br0. 2. __switchdev_handle_port_obj_add() recurses through br0's lowers, essentially calling __switchdev_handle_port_obj_add() for bond0 3. Go to step 1. This happens because switchdev_handle_fdb_event_to_device() and switchdev_handle_port_obj_add_foreign() are not exactly the same. The FDB event helper special-cases LAG interfaces with its lag_mod_cb(), so this is why we don't end up in an infinite loop - because it doesn't attempt to treat LAG interfaces as potentially foreign bridge ports. The problem is solved by looking ahead through the bridge's lowers to see whether there is any switchdev interface that is foreign to the @dev we are currently processing. This stops the recursion described above at step 1: __switchdev_handle_port_obj_add(bond0) will not create another call to __switchdev_handle_port_obj_add(br0). Going one step upper should only happen when we're starting from a bridge port that has been determined to be "foreign" to the switchdev driver that passes the foreign_dev_check_cb(). Fixes: c4076cdd21 ("net: switchdev: introduce switchdev_handle_port_obj_{add,del} for foreign interfaces") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2022-02-23 12:12:12 +00:00
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Kconfig
Makefile	net: switchdev: use obj-$(CONFIG_NET_SWITCHDEV) form in net/Makefile	2021-01-27 17:03:52 -08:00
switchdev.c	net: switchdev: avoid infinite recursion from LAG to bridge with port object handler	2022-02-23 12:12:12 +00:00