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

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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: 3f9bb0301d ("net: dsa: make dp->bridge_num one-based")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20260120211039.3228999-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Vladimir Oltean
2026-01-20 23:10:39 +02:00
committed by Jakub Kicinski
parent bbb11b8d75
commit dfca045cd4
1 changed files with 1 additions and 1 deletions
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2
net/dsa/dsa.c
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@@ -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);