[PATCH] nl80211: Do not attempt multicast NAN USD registration without support

[Jouni Malinen]

On Mon, Sep 07, 2026 at 12:06:12PM +0200, Nicolò Sala wrote:
> nl80211_mgmt_subscribe_non_ap() unconditionally attempts to register for
> group-addressed NAN SDF Public Action frames, and falls back to a
> non-multicast registration if that fails. On drivers that do not
> advertise NL80211_EXT_FEATURE_MULTICAST_REGISTRATIONS the first attempt
> is guaranteed to fail with -EOPNOTSUPP, and the kernel returns the
> extended ACK message "multicast RX registrations are not supported".
> 
> error_handler() prints any extack message at MSG_ERROR, so this expected
> and fully handled failure surfaces as an error to the user on every
> startup, once for the station interface and once for the P2P device
> interface:
> 
>   wlp0s20f3: nl80211: kernel reports: multicast RX registrations are not supported
>   p2p-dev-wlp0s20: nl80211: kernel reports: multicast RX registrations are not supported
> 
> Check drv->multicast_registrations before making the attempt and go
> straight to the non-multicast registration when the driver lacks the
> capability. This matches what nl80211_dpp_listen() already does and
> leaves behavior unchanged on drivers that do support it.

Thanks, applied.
 
-- 
Jouni Malinen                                            PGP id EFC895FA