Commit dfca045c authored by Vladimir Oltean's avatar Vladimir Oltean Committed by Jakub Kicinski
Browse files

net: dsa: fix off-by-one in maximum bridge ID determination 



Prior to the blamed commit, the bridge_num range was from
0 to ds->max_num_bridges - 1. After the commit, it is from
1 to ds->max_num_bridges.

So this check:
	if (bridge_num >= max)
		return 0;
must be updated to:
	if (bridge_num > max)
		return 0;

in order to allow the last bridge_num value (==max) to be used.

This is easiest visible when a driver sets ds->max_num_bridges=1.
The observed behaviour is that even the first created bridge triggers
the netlink extack "Range of offloadable bridges exceeded" warning, and
is handled in software rather than being offloaded.

Fixes: 3f9bb030 ("net: dsa: make dp->bridge_num one-based")
Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20260120211039.3228999-1-vladimir.oltean@nxp.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent bbb11b8d

net/dsa/dsa.c

+1 −1
Original line number Diff line number Diff line
@@ -158,7 +158,7 @@ unsigned int dsa_bridge_num_get(const struct net_device *bridge_dev, int max) 
		bridge_num = find_next_zero_bit(&dsa_fwd_offloading_bridges,

						DSA_MAX_NUM_OFFLOADING_BRIDGES,

						1);

		if (bridge_num >= max)

		if (bridge_num > max)

			return 0;



		set_bit(bridge_num, &dsa_fwd_offloading_bridges);