Re: [PATCH net] net: bridge: fdb: hold hash_lock when an entry roams

[Julius Bairaktaris]

(Resent with the lists on Cc; the first copy went to the To:
address only.)

On 04/10/2026 15:44, Nikolay Aleksandrov wrote:
> Absolutely not, this was made intentionally. Taking the hash_lock would further kill learning
> and roaming scaling. Surely switchdev drivers must have dealt with this for some time
> now, if you'd like to fix it do it so the software path isn't affected.

The fix moved to DSA, with br_fdb_update() unchanged: "[PATCH net-next
0/2] net: dsa: fix host fdb refcount when an entry roams". DSA no longer
counts the roam events; when it handles each event from its workqueue,
it looks up where the bridge has the entry. The only bridge change is
that RCU lookup and the filter it shares with br_switchdev_fdb_notify().

https://lore.kernel.org/netdev/cover.1794134495.git.julius@xxxxxxxxxxxxxx/

Julius