wifi: cfg80211: add cfg80211_stop_link() for per-link teardown

Currently, whenever cfg80211_stop_iface() is called, the entire iface
is stopped. However, there could be a need in AP/P2P_GO mode, where
one would like to stop a single link in MLO operation instead of the
whole MLD interface.

Hence, introduce cfg80211_stop_link() to allow drivers to tear down
only a specified AP/P2P_GO link during MLO operation. Passing -1
preserves the existing behavior of stopping the whole interface. Make
cfg80211_stop_iface() call this function by passing -1 to keep the
default behavior the same, that is, to stop all links and use
cfg80211_stop_link() with the desired link_id for AP/P2P_GO mode, to
stop only that link.

This brings no behavioral change for single-link/non-MLO interfaces,
and enables drivers to stop an AP/P2P_GO link without disrupting other
links on the same interface.

Signed-off-by: Manish Dharanenthiran <manish.dharanenthiran@oss.qualcomm.com>
Link: https://patch.msgid.link/20251127-stop_link-v2-1-43745846c5fd@qti.qualcomm.com
[make cfg80211_stop_iface() inline]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

7 files changed, 52 insertions, 20 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 899f267b7cf9..cbccedf32228 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -9788,6 +9788,21 @@ int cfg80211_iter_combinations(struct wiphy *wiphy,
 int cfg80211_get_radio_idx_by_chan(struct wiphy *wiphy,
 				   const struct ieee80211_channel *chan);
 
+/**
+ * cfg80211_stop_link - stop AP/P2P_GO link if link_id is non-negative or stops
+ *                      all links on the interface.
+ *
+ * @wiphy: the wiphy
+ * @wdev: wireless device
+ * @link_id: valid link ID in case of MLO AP/P2P_GO Operation or else -1
+ * @gfp: context flags
+ *
+ * If link_id is set during MLO operation, stops only the specified AP/P2P_GO
+ * link and if link_id is set to -1 or last link is stopped, the entire
+ * interface is stopped as if AP was stopped, IBSS/mesh left, STA disconnected.
+ */
+void cfg80211_stop_link(struct wiphy *wiphy, struct wireless_dev *wdev,
+			int link_id, gfp_t gfp);
 
 /**
  * cfg80211_stop_iface - trigger interface disconnection
@@ -9801,8 +9816,11 @@ int cfg80211_get_radio_idx_by_chan(struct wiphy *wiphy,
  *
  * Note: This doesn't need any locks and is asynchronous.
  */
-void cfg80211_stop_iface(struct wiphy *wiphy, struct wireless_dev *wdev,
-			 gfp_t gfp);
+static inline void
+cfg80211_stop_iface(struct wiphy *wiphy, struct wireless_dev *wdev, gfp_t gfp)
+{
+	cfg80211_stop_link(wiphy, wdev, -1, gfp);
+}
 
 /**
  * cfg80211_shutdown_all_interfaces - shut down all interfaces for a wiphy
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 9a420d627d3c..d0c7d9ff03b3 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -347,7 +347,7 @@ void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev)
 
 			guard(wiphy)(&rdev->wiphy);
 
-			cfg80211_leave(rdev, wdev);
+			cfg80211_leave(rdev, wdev, -1);
 			cfg80211_remove_virtual_intf(rdev, wdev);
 		}
 	}
@@ -1371,7 +1371,8 @@ void cfg80211_update_iface_num(struct cfg80211_registered_device *rdev,
 }
 
 void cfg80211_leave(struct cfg80211_registered_device *rdev,
-		    struct wireless_dev *wdev)
+		    struct wireless_dev *wdev,
+		    int link_id)
 {
 	struct net_device *dev = wdev->netdev;
 	struct cfg80211_sched_scan_request *pos, *tmp;
@@ -1409,7 +1410,7 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
 		break;
 	case NL80211_IFTYPE_AP:
 	case NL80211_IFTYPE_P2P_GO:
-		cfg80211_stop_ap(rdev, dev, -1, true);
+		cfg80211_stop_ap(rdev, dev, link_id, true);
 		break;
 	case NL80211_IFTYPE_OCB:
 		cfg80211_leave_ocb(rdev, dev);
@@ -1430,27 +1431,34 @@ void cfg80211_leave(struct cfg80211_registered_device *rdev,
 	}
 }
 
-void cfg80211_stop_iface(struct wiphy *wiphy, struct wireless_dev *wdev,
-			 gfp_t gfp)
+void cfg80211_stop_link(struct wiphy *wiphy, struct wireless_dev *wdev,
+			int link_id, gfp_t gfp)
 {
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
 	struct cfg80211_event *ev;
 	unsigned long flags;
 
-	trace_cfg80211_stop_iface(wiphy, wdev);
+	/* Only AP/GO interfaces may have a specific link_id */
+	if (WARN_ON_ONCE(link_id != -1 &&
+			 wdev->iftype != NL80211_IFTYPE_AP &&
+			 wdev->iftype != NL80211_IFTYPE_P2P_GO))
+		link_id = -1;
+
+	trace_cfg80211_stop_link(wiphy, wdev, link_id);
 
 	ev = kzalloc(sizeof(*ev), gfp);
 	if (!ev)
 		return;
 
 	ev->type = EVENT_STOPPED;
+	ev->link_id = link_id;
 
 	spin_lock_irqsave(&wdev->event_lock, flags);
 	list_add_tail(&ev->list, &wdev->event_list);
 	spin_unlock_irqrestore(&wdev->event_lock, flags);
 	queue_work(cfg80211_wq, &rdev->event_work);
 }
-EXPORT_SYMBOL(cfg80211_stop_iface);
+EXPORT_SYMBOL(cfg80211_stop_link);
 
 void cfg80211_init_wdev(struct wireless_dev *wdev)
 {
@@ -1589,7 +1597,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		break;
 	case NETDEV_GOING_DOWN:
 		scoped_guard(wiphy, &rdev->wiphy) {
-			cfg80211_leave(rdev, wdev);
+			cfg80211_leave(rdev, wdev, -1);
 			cfg80211_remove_links(wdev);
 		}
 		/* since we just did cfg80211_leave() nothing to do there */
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 63dcf315dba7..6ac57b7b2615 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -289,6 +289,7 @@ struct cfg80211_event {
 			u8 td_bitmap_len;
 		} pa;
 	};
+	int link_id;
 };
 
 struct cfg80211_cached_keys {
@@ -537,7 +538,8 @@ void cfg80211_update_iface_num(struct cfg80211_registered_device *rdev,
 			       enum nl80211_iftype iftype, int num);
 
 void cfg80211_leave(struct cfg80211_registered_device *rdev,
-		    struct wireless_dev *wdev);
+		    struct wireless_dev *wdev,
+		    int link_id);
 
 void cfg80211_stop_p2p_device(struct cfg80211_registered_device *rdev,
 			      struct wireless_dev *wdev);
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 73cab51f6379..a8ab0ab22d90 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -2442,7 +2442,7 @@ static void reg_leave_invalid_chans(struct wiphy *wiphy)
 
 	list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list)
 		if (!reg_wdev_chan_valid(wiphy, wdev))
-			cfg80211_leave(rdev, wdev);
+			cfg80211_leave(rdev, wdev, -1);
 }
 
 static void reg_check_chans_work(struct work_struct *work)
diff --git a/net/wireless/sysfs.c b/net/wireless/sysfs.c
index 8d142856e385..2e0ea69b9604 100644
--- a/net/wireless/sysfs.c
+++ b/net/wireless/sysfs.c
@@ -88,7 +88,7 @@ static void cfg80211_leave_all(struct cfg80211_registered_device *rdev)
 	struct wireless_dev *wdev;
 
 	list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list)
-		cfg80211_leave(rdev, wdev);
+		cfg80211_leave(rdev, wdev, -1);
 }
 
 static int wiphy_suspend(struct device *dev)
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 2b71f1d867a0..643ccf4f0227 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -3915,19 +3915,22 @@ TRACE_EVENT(cfg80211_ft_event,
 		  WIPHY_PR_ARG, NETDEV_PR_ARG, __entry->target_ap)
 );
 
-TRACE_EVENT(cfg80211_stop_iface,
-	TP_PROTO(struct wiphy *wiphy, struct wireless_dev *wdev),
-	TP_ARGS(wiphy, wdev),
+TRACE_EVENT(cfg80211_stop_link,
+	TP_PROTO(struct wiphy *wiphy, struct wireless_dev *wdev,
+		 int link_id),
+	TP_ARGS(wiphy, wdev, link_id),
 	TP_STRUCT__entry(
 		WIPHY_ENTRY
 		WDEV_ENTRY
+		__field(int, link_id)
 	),
 	TP_fast_assign(
 		WIPHY_ASSIGN;
 		WDEV_ASSIGN;
+		__entry->link_id = link_id;
 	),
-	TP_printk(WIPHY_PR_FMT ", " WDEV_PR_FMT,
-		  WIPHY_PR_ARG, WDEV_PR_ARG)
+	TP_printk(WIPHY_PR_FMT ", " WDEV_PR_FMT ", link_id: %d",
+		  WIPHY_PR_ARG, WDEV_PR_ARG, __entry->link_id)
 );
 
 TRACE_EVENT(cfg80211_pmsr_report,
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 27e8a2f52f04..cc55b759694e 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1144,7 +1144,8 @@ void cfg80211_process_wdev_events(struct wireless_dev *wdev)
 					       ev->ij.channel);
 			break;
 		case EVENT_STOPPED:
-			cfg80211_leave(wiphy_to_rdev(wdev->wiphy), wdev);
+			cfg80211_leave(wiphy_to_rdev(wdev->wiphy), wdev,
+				       ev->link_id);
 			break;
 		case EVENT_PORT_AUTHORIZED:
 			__cfg80211_port_authorized(wdev, ev->pa.peer_addr,
@@ -1203,7 +1204,7 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
 		dev->ieee80211_ptr->use_4addr = false;
 		rdev_set_qos_map(rdev, dev, NULL);
 
-		cfg80211_leave(rdev, dev->ieee80211_ptr);
+		cfg80211_leave(rdev, dev->ieee80211_ptr, -1);
 
 		cfg80211_process_rdev_events(rdev);
 		cfg80211_mlme_purge_registrations(dev->ieee80211_ptr);