wifi: mac80211: stop using ieee80211_mgmt_tx_cookie()

Now that cfg80211 pre-assigns the cookie before calling into mac80211,
stop calling ieee80211_mgmt_tx_cookie() in all affected paths:

- ieee80211_start_roc_work(): for normal ROC use the pre-assigned value
  directly instead of generating a new one.
- ieee80211_attach_ack_skb(): the cookie is already set by the caller;
  remove the ieee80211_mgmt_tx_cookie() call and store it in the ack
  SKB as-is. This covers both mgmt_tx and probe_peer since both call
  ieee80211_attach_ack_skb().
- ieee80211_mgmt_tx(): the dummy 0xffffffff assignment for the
  dont_wait_for_ack case is no longer needed; cfg80211_assign_cookie()
  guarantees a non-zero value which is sufficient for the internal
  ROC vs mgmt-tx distinction.
- ieee80211_store_ack_skb(): same fix for the tx_control_port path.

With no remaining callers, remove ieee80211_mgmt_tx_cookie() and the
roc_cookie_counter field from struct ieee80211_local.

Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Link: https://patch.msgid.link/20260731123509.1975281-3-arend.vanspriel@broadcom.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -4831,19 +4831,6 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 	return __ieee80211_channel_switch(wiphy, dev, params);
 }
 
-u64 ieee80211_mgmt_tx_cookie(struct ieee80211_local *local)
-{
-	lockdep_assert_wiphy(local->hw.wiphy);
-
-	local->roc_cookie_counter++;
-
-	/* wow, you wrapped 64 bits ... more likely a bug */
-	if (WARN_ON(local->roc_cookie_counter == 0))
-		local->roc_cookie_counter++;
-
-	return local->roc_cookie_counter;
-}
-
 int ieee80211_attach_ack_skb(struct ieee80211_local *local, struct sk_buff *skb,
 			     u64 *cookie, gfp_t gfp)
 {
@@ -4868,7 +4855,6 @@ int ieee80211_attach_ack_skb(struct ieee80211_local *local, struct sk_buff *skb,
 	IEEE80211_SKB_CB(skb)->status_data_idr = 1;
 	IEEE80211_SKB_CB(skb)->status_data = id;
 
-	*cookie = ieee80211_mgmt_tx_cookie(local);
 	IEEE80211_SKB_CB(ack_skb)->ack.cookie = *cookie;
 
 	return 0;

net/mac80211/ieee80211_i.h

@@ -1710,8 +1710,6 @@ struct ieee80211_local {
 	struct list_head roc_list;
 	struct wiphy_work hw_roc_start, hw_roc_done;
 	unsigned long hw_roc_start_time;
-	u64 roc_cookie_counter;
-
 	struct idr ack_status_frames;
 	spinlock_t ack_status_lock;
 
@@ -1991,7 +1989,6 @@ u64 ieee80211_reset_erp_info(struct ieee80211_sub_if_data *sdata);
 
 void ieee80211_handle_queued_frames(struct ieee80211_local *local);
 
-u64 ieee80211_mgmt_tx_cookie(struct ieee80211_local *local);
 int ieee80211_attach_ack_skb(struct ieee80211_local *local, struct sk_buff *skb,
 			     u64 *cookie, gfp_t gfp);
 

net/mac80211/offchannel.c

@@ -602,14 +602,12 @@ static int ieee80211_start_roc_work(struct ieee80211_local *local,
 
 	/*
 	 * cookie is either the roc cookie (for normal roc)
-	 * or the SKB (for mgmt TX)
+	 * or the mgmt_tx cookie; both are pre-assigned by cfg80211
 	 */
-	if (!txskb) {
-		roc->cookie = ieee80211_mgmt_tx_cookie(local);
-		*cookie = roc->cookie;
-	} else {
+	if (!txskb)
+		roc->cookie = *cookie;
+	else
 		roc->mgmt_tx_cookie = *cookie;
-	}
 
 	req = wiphy_dereference(local->hw.wiphy, local->scan_req);
 
@@ -1021,13 +1019,6 @@ int ieee80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev,
 			kfree_skb(skb);
 			goto out_unlock;
 		}
-	} else {
-		/* Assign a dummy non-zero cookie, it's not sent to
-		 * userspace in this case but we rely on its value
-		 * internally in the need_offchan case to distinguish
-		 * mgmt-tx from remain-on-channel.
-		 */
-		*cookie = 0xffffffff;
 	}
 
 	if (!need_offchan) {

net/mac80211/tx.c

@@ -2602,10 +2602,8 @@ static u16 ieee80211_store_ack_skb(struct ieee80211_local *local,
 		if (id >= 0) {
 			info_id = id;
 			*info_flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
-			if (cookie) {
-				*cookie = ieee80211_mgmt_tx_cookie(local);
+			if (cookie)
 				IEEE80211_SKB_CB(ack_skb)->ack.cookie = *cookie;
-			}
 		} else {
 			kfree_skb(ack_skb);
 		}