[PATCH v2] driver_nl80211: report invalid signal and noise when info is unavailable

[Matthew Wang]

In wpa_bss_update_level, we should probably continue to check for
new_level < 0 as well as new_level > -WPA_INVALID_NOISE.

On Sun, Sep 13, 2020 at 6:00 AM Andrei Otcheretianski
<andrei.otcheretianski at intel.com> wrote:
>
> From: Avraham Stern <avraham.stern at intel.com>
>
> When the driver sends a CQM RSSI threshold event, wpa_supplicant
> queries the driver for the signal and noise values. However, it
> is possible that by that time the station has already disconnected
> from the AP, so these values are no longer valid. In this case,
> indicate that these values are invalid by setting them to
> WPA_INVALID_NOISE.
> Previously a value of 0 would be reported, which may be confusing as
> this is a valid value.
> Since nl80211_get_link_signal() and nl80211_get_link_noise() already
> set invalid values for a case of failure, just use the value set by
> these functions even if they fail.
>
> Signed-off-by: Avraham Stern <avraham.stern at intel.com>
> Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski at intel.com>
> ---
>  src/drivers/driver_nl80211_event.c | 26 ++++++++++++++++----------
>  wpa_supplicant/bss.h               |  2 +-
>  2 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/src/drivers/driver_nl80211_event.c b/src/drivers/driver_nl80211_event.c
> index ce95e9cd39..31b2799535 100644
> --- a/src/drivers/driver_nl80211_event.c
> +++ b/src/drivers/driver_nl80211_event.c
> @@ -1277,7 +1277,6 @@ static void nl80211_cqm_event(struct wpa_driver_nl80211_data *drv,
>         struct nlattr *cqm[NL80211_ATTR_CQM_MAX + 1];
>         enum nl80211_cqm_rssi_threshold_event event;
>         union wpa_event_data ed;
> -       struct wpa_signal_info sig;
>         int res;
>
>         if (tb[NL80211_ATTR_CQM] == NULL ||
> @@ -1344,20 +1343,27 @@ static void nl80211_cqm_event(struct wpa_driver_nl80211_data *drv,
>                 return;
>         }
>
> -       res = nl80211_get_link_signal(drv, &sig);
> +       /*
> +        * nl80211_get_link_signal() and nl80211_get_link_noise() set default
> +        * values in case querying the driver fails.
> +        */
> +       res = nl80211_get_link_signal(drv, &ed.signal_change);
>         if (res == 0) {
> -               ed.signal_change.current_signal = sig.current_signal;
> -               ed.signal_change.current_txrate = sig.current_txrate;
>                 wpa_printf(MSG_DEBUG, "nl80211: Signal: %d dBm  txrate: %d",
> -                          sig.current_signal, sig.current_txrate);
> +                          ed.signal_change.current_signal,
> +                          ed.signal_change.current_txrate);
> +       } else {
> +               wpa_printf(MSG_DEBUG,
> +                          "nl80211: querying the driver for signal info failed");
>         }
>
> -       res = nl80211_get_link_noise(drv, &sig);
> -       if (res == 0) {
> -               ed.signal_change.current_noise = sig.current_noise;
> +       res = nl80211_get_link_noise(drv, &ed.signal_change);
> +       if (res == 0)
>                 wpa_printf(MSG_DEBUG, "nl80211: Noise: %d dBm",
> -                          sig.current_noise);
> -       }
> +                          ed.signal_change.current_noise);
> +       else
> +               wpa_printf(MSG_DEBUG,
> +                          "nl80211: querying the driver for noise info failed");
>
>         wpa_supplicant_event(drv->ctx, EVENT_SIGNAL_CHANGE, &ed);
>  }
> diff --git a/wpa_supplicant/bss.h b/wpa_supplicant/bss.h
> index 0716761749..750cdcbccc 100644
> --- a/wpa_supplicant/bss.h
> +++ b/wpa_supplicant/bss.h
> @@ -169,7 +169,7 @@ static inline int bss_is_pbss(struct wpa_bss *bss)
>
>  static inline void wpa_bss_update_level(struct wpa_bss *bss, int new_level)
>  {
> -       if (bss != NULL && new_level < 0)
> +       if (bss != NULL && new_level > -WPA_INVALID_NOISE)
>                 bss->level = new_level;
>  }
>
> --
> 2.28.0
>
>
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