On Thu, 2018-02-08 at 09:49 +0000, Jean Pierre TOSONI wrote: > In net/mac80211/scan.c, function ieee80211_bss_info_update() passes > incoming scan results to the generic wireless layer, with indication of > the received signal level, but no indication of signal validity.
Well, there is an indication of validity, if the value is 0 then it's invalid. > Before ieee80211_bss_info_update() is called, rx_status->flag can be set > to RX_FLAG_NO_SIGNAL_VAL by the ath9k driver and it won't be taken into > account in the wireless layer. > Even later in ieee80211_bss_info_update(), rx_status->flag can also be set > to RX_FLAG_NO_SIGNAL_VAL, and the wireless layer won't be aware of this. However, it looks like you're right and ieee80211_bss_info_update() doesn't take the flag into account. Bit strange that we even have the flag I guess, since we treat 0 as an invalid value in various places, being too high power to realistically receive anyway. > I stumbled on this because, when using ath9k (WLE350NX) to do a passive scan > off-channel, the beacons received in a 30ms window after channel change show > a signal level +10dB above the real value. So I was looking for a way to > tell the above layers that the signal is invalid. RX_FLAG_NO_SIGNAL_VAL seems > to fit, but is not conveyed up to iw or wpa_supplicant. > > In fact I did not find any such thing in net/wireless/nl80211.c, function > nl80211_send_bss(). > > Any suggestion? Did I miss something? Want to send a patch? There seem to be a few more places as well, e.g. in rx.c for cfg80211_report_obss_beacon() and cfg80211_rx_mgmt(). johannes
