FS#2698 - netifd DFS-delayed wireless interfaces not correctly handled

[openwrt-bot]

oldium:

Found on TP-Link Archer C7 v4 on master (commit db992e7 - 5 days ago).

When having 3 interfaces on channel requiring radar scan (DFS), only the main interface is shown - see logs, where radio0 wifi should have 3 interfaces wlan0-lan, wlan0-guest and wlan0-admin, but only wlan0-lan is shown. Due to DFS scan it comes up after a minute after /etc/init.d/network start is executed.

Configuration:

• 2 wifis: 2,4GHz (radio1) + 5GHz (radio0)
• each band has 3 SSIDs (domaci-soukroma, domaci, domaci-admin), each one's interface assigned to one bridge - lan, guest and admin, respectively.

Called ubus call network.wireless status, received result:

• wlan0-lan exists
• wlan0-guest and wlan0-admin not recognised
• wlan1-lan, wlan1-guest, wlan1-admin exist

Expected result:

• wlan0-guest and wlan0-admin recognised

Configuration, logread (produced by /sbin/netifd -d 15 -l 7), ubus network.device status and ubus network.wireless status attached (removed IP and MAC addresses).

[openwrt-bot]

oldium:

The problem might be in mac80211.sh, which on line 518 states:

Hostapd will handle recreating the interface and

subsequent virtual APs belonging to the same PHY

This is true for interfaces wlan0-guest and wlan0-admin, which are created after wlan0-lan comes up. But before this happens, the mac80211_setup_vif is called and tries to do (see lines 750-755):

logger ip link set dev "$ifname" $action
ip link set dev "$ifname" "$action" || {
wireless_setup_vif_failed IFUP_ERROR
json_select ..
return
}

This needs to be postponed for wlan0-guest and wlan0-admin until the main interface wlan0-lan comes up. I believe this is worked-around also in function drv_mac80211_setup on line 962, which states:

[ "${add_ap}" = 1 ] && sleep 1
for_each_interface "ap" mac80211_setup_vif

So it gives hostapd 1 second to come up. But problem with wlan0-guest and wlan0-admin is that they come up after 60 seconds as soon as DFS scan finishes and wlan0-lan comes up.

[openwrt-bot]

oldium:

Added generated hostapd configs. Main interface on phy0 in the attached config is interface=wlan0-lan, others are bss=wlan0-guest and bss=wlan0-admin. phy0 does not work (uses channel requiring DFS scan on 5GHz band), phy1 works (2.4GHz band, no DFS required).

[openwrt-bot]

oldium:

Fixed by [[https://github.com//pull/2848|pull request 2848]].

[openwrt-bot]

dangowrt:

Fixed in master since commit [[https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=23a885bf89a204f91e4f17ed96f1a9fc7f50ea34|23a885bf89a204f91e4f17ed96f1a9fc7f50ea34]]