[RFC] mac80211_hwsim: report survey data for scanned channels

[RFC] mac80211_hwsim: report survey data for scanned channels

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

Currently, hwsim is reporting survey data (only a fake noise floor)
for the current channel. This breaks when the multi-channel support
is enabled since then there's no current channel.

Make the dummy implementation closer to a real one and only report
data while scanning, for all the scanned channels. At other times,
no survey data might be available (in real hardware) due to power-
save for example.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
Had this lying around - is it useful for anyone?
---
 drivers/net/wireless/mac80211_hwsim.c | 73 ++++++++++++++++++++++++++++-------
 1 file changed, 60 insertions(+), 13 deletions(-)

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 0150747c79ac..5a636b09320b 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -525,6 +525,11 @@ struct mac80211_hwsim_data {
 	struct ieee80211_vif *hw_scan_vif;
 	int scan_chan_idx;
 	u8 scan_addr[ETH_ALEN];
+	struct {
+		struct ieee80211_channel *channel;
+		unsigned long next_start, start, end;
+	} survey_data[ARRAY_SIZE(hwsim_channels_2ghz) +
+		      ARRAY_SIZE(hwsim_channels_5ghz)];
 
 	struct ieee80211_channel *channel;
 	u64 beacon_int	/* beacon interval in us */;
@@ -1576,6 +1581,7 @@ static int mac80211_hwsim_config(struct ieee80211_hw *hw, u32 changed)
 		[IEEE80211_SMPS_STATIC] = "static",
 		[IEEE80211_SMPS_DYNAMIC] = "dynamic",
 	};
+	int idx;
 
 	if (conf->chandef.chan)
 		wiphy_debug(hw->wiphy,
@@ -1598,9 +1604,33 @@ static int mac80211_hwsim_config(struct ieee80211_hw *hw, u32 changed)
 
 	data->idle = !!(conf->flags & IEEE80211_CONF_IDLE);
 
-	data->channel = conf->chandef.chan;
+	WARN_ON(conf->chandef.chan && data->use_chanctx);
+
+	mutex_lock(&data->mutex);
+	if (data->scanning && conf->chandef.chan) {
+		for (idx = 0; idx < ARRAY_SIZE(data->survey_data); idx++) {
+			if (data->survey_data[idx].channel == data->channel) {
+				data->survey_data[idx].start =
+					data->survey_data[idx].next_start;
+				data->survey_data[idx].end = jiffies;
+				break;
+			}
+		}
 
-	WARN_ON(data->channel && data->use_chanctx);
+		data->channel = conf->chandef.chan;
+
+		for (idx = 0; idx < ARRAY_SIZE(data->survey_data); idx++) {
+			if (data->survey_data[idx].channel &&
+			    data->survey_data[idx].channel != data->channel)
+				continue;
+			data->survey_data[idx].channel = data->channel;
+			data->survey_data[idx].next_start = jiffies;
+			break;
+		}
+	} else {
+		data->channel = conf->chandef.chan;
+	}
+	mutex_unlock(&data->mutex);
 
 	data->power_level = conf->power_level;
 	if (!data->started || !data->beacon_int)
@@ -1787,28 +1817,39 @@ static int mac80211_hwsim_conf_tx(
 	return 0;
 }
 
-static int mac80211_hwsim_get_survey(
-	struct ieee80211_hw *hw, int idx,
-	struct survey_info *survey)
+static int mac80211_hwsim_get_survey(struct ieee80211_hw *hw, int idx,
+				     struct survey_info *survey)
 {
-	struct ieee80211_conf *conf = &hw->conf;
+	struct mac80211_hwsim_data *hwsim = hw->priv;
 
 	wiphy_debug(hw->wiphy, "%s (idx=%d)\n", __func__, idx);
 
-	if (idx != 0)
+	if (idx < 0 || idx >= ARRAY_SIZE(hwsim->survey_data))
 		return -ENOENT;
 
-	/* Current channel */
-	survey->channel = conf->chandef.chan;
+	mutex_lock(&hwsim->mutex);
+	survey->channel = hwsim->survey_data[idx].channel;
+	if (!survey->channel) {
+		mutex_unlock(&hwsim->mutex);
+		return -ENOENT;
+	}
 
 	/*
-	 * Magically conjured noise level --- this is only ok for simulated hardware.
+	 * Magically conjured dummy values --- this is only ok for simulated hardware.
 	 *
-	 * A real driver which cannot determine the real channel noise MUST NOT
-	 * report any noise, especially not a magically conjured one :-)
+	 * A real driver which cannot determine real values noise MUST NOT
+	 * report any, especially not a magically conjured ones :-)
 	 */
-	survey->filled = SURVEY_INFO_NOISE_DBM;
+	survey->filled = SURVEY_INFO_NOISE_DBM |
+			 SURVEY_INFO_CHANNEL_TIME |
+			 SURVEY_INFO_CHANNEL_TIME_BUSY;
 	survey->noise = -92;
+	survey->channel_time =
+		jiffies_to_msecs(hwsim->survey_data[idx].end -
+				 hwsim->survey_data[idx].start);
+	/* report 12.5% of channel time is used */
+	survey->channel_time_busy = survey->channel_time/8;
+	mutex_unlock(&hwsim->mutex);
 
 	return 0;
 }
@@ -1986,6 +2027,10 @@ static void hw_scan_work(struct work_struct *work)
 	}
 	ieee80211_queue_delayed_work(hwsim->hw, &hwsim->hw_scan,
 				     msecs_to_jiffies(dwell));
+	hwsim->survey_data[hwsim->scan_chan_idx].channel = hwsim->tmp_chan;
+	hwsim->survey_data[hwsim->scan_chan_idx].start = jiffies;
+	hwsim->survey_data[hwsim->scan_chan_idx].end =
+		jiffies + msecs_to_jiffies(dwell);
 	hwsim->scan_chan_idx++;
 	mutex_unlock(&hwsim->mutex);
 }
@@ -2011,6 +2056,7 @@ static int mac80211_hwsim_hw_scan(struct ieee80211_hw *hw,
 				     hw_req->req.mac_addr_mask);
 	else
 		memcpy(hwsim->scan_addr, vif->addr, ETH_ALEN);
+	memset(hwsim->survey_data, 0, sizeof(hwsim->survey_data));
 	mutex_unlock(&hwsim->mutex);
 
 	wiphy_debug(hw->wiphy, "hwsim hw_scan request\n");
@@ -2057,6 +2103,7 @@ static void mac80211_hwsim_sw_scan(struct ieee80211_hw *hw,
 
 	memcpy(hwsim->scan_addr, mac_addr, ETH_ALEN);
 	hwsim->scanning = true;
+	memset(hwsim->survey_data, 0, sizeof(hwsim->survey_data));
 
 out:
 	mutex_unlock(&hwsim->mutex);
-- 
2.9.3

Re: [RFC] mac80211_hwsim: report survey data for scanned channels

[Jouni Malinen]

On Tue, Feb 21, 2017 at 11:31:18AM +0100, Johannes Berg wrote:
> Currently, hwsim is reporting survey data (only a fake noise floor)
> for the current channel. This breaks when the multi-channel support
> is enabled since then there's no current channel.
> 
> Make the dummy implementation closer to a real one and only report
> data while scanning, for all the scanned channels. At other times,
> no survey data might be available (in real hardware) due to power-
> save for example.

> Had this lying around - is it useful for anyone?

Yes, it seems to make the ap_acs hwsim test cases in hostap.git quite a
bit more useful in hitting proper acs.c coverage in hostapd.. And also
allow having to have hacks to force previous AP instance on the same
band just to be able to hit any of this code.

> -	survey->filled = SURVEY_INFO_NOISE_DBM;
> +	survey->filled = SURVEY_INFO_NOISE_DBM |
> +			 SURVEY_INFO_CHANNEL_TIME |
> +			 SURVEY_INFO_CHANNEL_TIME_BUSY;

This is pretty old, though.. :)  Had to remove the "CHANNEL_" part
here..

> +	survey->channel_time =
> +	survey->channel_time_busy = survey->channel_time/8;

.. and "channel_" in these to make this compile. Anyway, with those
trivial changes, the hwsim test cases did start looking more
interesting, so it would seem reasonable to get this applied.

-- 
Jouni Malinen                                            PGP id EFC895FA

Re: [RFC] mac80211_hwsim: report survey data for scanned channels

[Johannes Berg]

On Sat, 2017-03-04 at 11:10 +0200, Jouni Malinen wrote:
> On Tue, Feb 21, 2017 at 11:31:18AM +0100, Johannes Berg wrote:
> > Currently, hwsim is reporting survey data (only a fake noise floor)
> > for the current channel. This breaks when the multi-channel support
> > is enabled since then there's no current channel.
> > 
> > Make the dummy implementation closer to a real one and only report
> > data while scanning, for all the scanned channels. At other times,
> > no survey data might be available (in real hardware) due to power-
> > save for example.
> > Had this lying around - is it useful for anyone?
> 
> Yes, it seems to make the ap_acs hwsim test cases in hostap.git quite
> a
> bit more useful in hitting proper acs.c coverage in hostapd.. And
> also
> allow having to have hacks to force previous AP instance on the same
> band just to be able to hit any of this code.
> 
> > -	survey->filled = SURVEY_INFO_NOISE_DBM;
> > +	survey->filled = SURVEY_INFO_NOISE_DBM |
> > +			 SURVEY_INFO_CHANNEL_TIME |
> > +			 SURVEY_INFO_CHANNEL_TIME_BUSY;
> 
> This is pretty old, though.. :)  Had to remove the "CHANNEL_" part
> here..
> 
> > +	survey->channel_time =
> > +	survey->channel_time_busy = survey->channel_time/8;
> 
> .. and "channel_" in these to make this compile.

Right, yeah.

> Anyway, with those
> trivial changes, the hwsim test cases did start looking more
> interesting, so it would seem reasonable to get this applied.

Applied it now with the fixes.

johannes