mac80211: Handle the CSA counters correctly

Make the beacon CSA counters part of ieee80211_mutable_offsets and don't
decrement CSA counters when generating a beacon template. This permits the
driver to offload the CSA counters handling. Since mac80211 updates the probe
responses with the correct counter, the driver should sync the counter's value
with mac80211 using ieee80211_csa_update_counter function.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 58 insertions, 24 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index d44dca5..bfd2534 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -3502,10 +3502,10 @@ static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev,
 	     sdata->vif.type == NL80211_IFTYPE_ADHOC) &&
 	    params->n_csa_offsets) {
 		int i;
+		u8 c = sdata->csa_current_counter;
 
 		for (i = 0; i < params->n_csa_offsets; i++)
-			data[params->csa_offsets[i]] =
-					sdata->csa_current_counter;
+			data[params->csa_offsets[i]] = c;
 	}
 
 	IEEE80211_SKB_CB(skb)->flags = flags;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 05ed592..57e0b26 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -70,8 +70,6 @@ struct ieee80211_local;
 
 #define IEEE80211_DEAUTH_FRAME_LEN	(24 /* hdr */ + 2 /* reason */)
 
-#define IEEE80211_MAX_CSA_COUNTERS_NUM 2
-
 struct ieee80211_fragment_entry {
 	unsigned long first_frag_time;
 	unsigned int seq;
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 509456e..5214686 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2416,13 +2416,14 @@ static int ieee80211_beacon_add_tim(struct ieee80211_sub_if_data *sdata,
 	return 0;
 }
 
-static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata,
-				 struct beacon_data *beacon)
+static void ieee80211_set_csa(struct ieee80211_sub_if_data *sdata,
+			      struct beacon_data *beacon)
 {
 	struct probe_resp *resp;
 	u8 *beacon_data;
 	size_t beacon_data_len;
 	int i;
+	u8 count = sdata->csa_current_counter;
 
 	switch (sdata->vif.type) {
 	case NL80211_IFTYPE_AP:
@@ -2450,16 +2451,7 @@ static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata,
 			if (WARN_ON(counter_offset_beacon >= beacon_data_len))
 				return;
 
-			/* Warn if the driver did not check for/react to csa
-			 * completeness.  A beacon with CSA counter set to 0
-			 * should never occur, because a counter of 1 means
-			 * switch just before the next beacon.
-			 */
-			if (WARN_ON(beacon_data[counter_offset_beacon] == 1))
-				return;
-
-			beacon_data[counter_offset_beacon] =
-				sdata->csa_current_counter - 1;
+			beacon_data[counter_offset_beacon] = count;
 		}
 
 		if (sdata->vif.type == NL80211_IFTYPE_AP &&
@@ -2474,14 +2466,24 @@ static void ieee80211_update_csa(struct ieee80211_sub_if_data *sdata,
 				rcu_read_unlock();
 				return;
 			}
-			resp->data[counter_offset_presp] =
-				sdata->csa_current_counter - 1;
+			resp->data[counter_offset_presp] = count;
 			rcu_read_unlock();
 		}
 	}
+}
+
+u8 ieee80211_csa_update_counter(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 
 	sdata->csa_current_counter--;
+
+	/* the counter should never reach 0 */
+	WARN_ON(!sdata->csa_current_counter);
+
+	return sdata->csa_current_counter;
 }
+EXPORT_SYMBOL(ieee80211_csa_update_counter);
 
 bool ieee80211_csa_is_complete(struct ieee80211_vif *vif)
 {
@@ -2552,6 +2554,7 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw,
 	enum ieee80211_band band;
 	struct ieee80211_tx_rate_control txrc;
 	struct ieee80211_chanctx_conf *chanctx_conf;
+	int csa_off_base = 0;
 
 	rcu_read_lock();
 
@@ -2569,8 +2572,12 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw,
 		struct beacon_data *beacon = rcu_dereference(ap->beacon);
 
 		if (beacon) {
-			if (sdata->vif.csa_active)
-				ieee80211_update_csa(sdata, beacon);
+			if (sdata->vif.csa_active) {
+				if (!is_template)
+					ieee80211_csa_update_counter(vif);
+
+				ieee80211_set_csa(sdata, beacon);
+			}
 
 			/*
 			 * headroom, head length,
@@ -2593,6 +2600,9 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw,
 			if (offs) {
 				offs->tim_offset = beacon->head_len;
 				offs->tim_length = skb->len - beacon->head_len;
+
+				/* for AP the csa offsets are from tail */
+				csa_off_base = skb->len;
 			}
 
 			if (beacon->tail)
@@ -2608,9 +2618,12 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw,
 		if (!presp)
 			goto out;
 
-		if (sdata->vif.csa_active)
-			ieee80211_update_csa(sdata, presp);
+		if (sdata->vif.csa_active) {
+			if (!is_template)
+				ieee80211_csa_update_counter(vif);
 
+			ieee80211_set_csa(sdata, presp);
+		}
 
 		skb = dev_alloc_skb(local->tx_headroom + presp->head_len +
 				    local->hw.extra_beacon_tailroom);
@@ -2630,8 +2643,17 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw,
 		if (!bcn)
 			goto out;
 
-		if (sdata->vif.csa_active)
-			ieee80211_update_csa(sdata, bcn);
+		if (sdata->vif.csa_active) {
+			if (!is_template)
+				/* TODO: For mesh csa_counter is in TU, so
+				 * decrementing it by one isn't correct, but
+				 * for now we leave it consistent with overall
+				 * mac80211's behavior.
+				 */
+				ieee80211_csa_update_counter(vif);
+
+			ieee80211_set_csa(sdata, bcn);
+		}
 
 		if (ifmsh->sync_ops)
 			ifmsh->sync_ops->adjust_tbtt(sdata, bcn);
@@ -2658,6 +2680,20 @@ __ieee80211_beacon_get(struct ieee80211_hw *hw,
 		goto out;
 	}
 
+	/* CSA offsets */
+	if (offs) {
+		int i;
+
+		for (i = 0; i < IEEE80211_MAX_CSA_COUNTERS_NUM; i++) {
+			u16 csa_off = sdata->csa_counter_offset_beacon[i];
+
+			if (!csa_off)
+				continue;
+
+			offs->csa_counter_offs[i] = csa_off_base + csa_off;
+		}
+	}
+
 	band = chanctx_conf->def.chan->band;
 
 	info = IEEE80211_SKB_CB(skb);