wifi: mac80211: move color collision detection report in a delayed work

Move color collision report in a dedicated delayed work and do not run
it in interrupt context in order to rate-limit the number of events
reported to userspace. Moreover grab wdev mutex in
ieee80211_color_collision_detection_work routine since it is required
by cfg80211_obss_color_collision_notify().

Tested-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Fixes: 5f9404a ("mac80211: add support for BSS color change")
Link: https://lore.kernel.org/r/3f6cf60c892ad40c1cca4a55d62b1224ef1c6ce9.1674644379.git.lorenzo@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -4652,6 +4652,20 @@ void ieee80211_color_change_finalize_work(struct work_struct *work)
 	sdata_unlock(sdata);
 }
 
+void ieee80211_color_collision_detection_work(struct work_struct *work)
+{
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct ieee80211_link_data *link =
+		container_of(delayed_work, struct ieee80211_link_data,
+			     color_collision_detect_work);
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+
+	sdata_lock(sdata);
+	cfg80211_obss_color_collision_notify(sdata->dev, link->color_bitmap,
+					     GFP_KERNEL);
+	sdata_unlock(sdata);
+}
+
 void ieee80211_color_change_finish(struct ieee80211_vif *vif)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
@@ -4666,11 +4680,21 @@ ieee80211_obss_color_collision_notify(struct ieee80211_vif *vif,
 				       u64 color_bitmap, gfp_t gfp)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+	struct ieee80211_link_data *link = &sdata->deflink;
 
 	if (sdata->vif.bss_conf.color_change_active || sdata->vif.bss_conf.csa_active)
 		return;
 
-	cfg80211_obss_color_collision_notify(sdata->dev, color_bitmap, gfp);
+	if (delayed_work_pending(&link->color_collision_detect_work))
+		return;
+
+	link->color_bitmap = color_bitmap;
+	/* queue the color collision detection event every 500 ms in order to
+	 * avoid sending too much netlink messages to userspace.
+	 */
+	ieee80211_queue_delayed_work(&sdata->local->hw,
+				     &link->color_collision_detect_work,
+				     msecs_to_jiffies(500));
 }
 EXPORT_SYMBOL_GPL(ieee80211_obss_color_collision_notify);
 

net/mac80211/ieee80211_i.h

@@ -974,6 +974,8 @@ struct ieee80211_link_data {
 	struct cfg80211_chan_def csa_chandef;
 
 	struct work_struct color_change_finalize_work;
+	struct delayed_work color_collision_detect_work;
+	u64 color_bitmap;
 
 	/* context reservation -- protected with chanctx_mtx */
 	struct ieee80211_chanctx *reserved_chanctx;
@@ -1929,6 +1931,7 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,
 
 /* color change handling */
 void ieee80211_color_change_finalize_work(struct work_struct *work);
+void ieee80211_color_collision_detection_work(struct work_struct *work);
 
 /* interface handling */
 #define MAC80211_SUPPORTED_FEATURES_TX	(NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM | \

net/mac80211/link.c

@@ -39,6 +39,8 @@ void ieee80211_link_init(struct ieee80211_sub_if_data *sdata,
 		  ieee80211_csa_finalize_work);
 	INIT_WORK(&link->color_change_finalize_work,
 		  ieee80211_color_change_finalize_work);
+	INIT_DELAYED_WORK(&link->color_collision_detect_work,
+			  ieee80211_color_collision_detection_work);
 	INIT_LIST_HEAD(&link->assigned_chanctx_list);
 	INIT_LIST_HEAD(&link->reserved_chanctx_list);
 	INIT_DELAYED_WORK(&link->dfs_cac_timer_work,
@@ -66,6 +68,7 @@ void ieee80211_link_stop(struct ieee80211_link_data *link)
 	if (link->sdata->vif.type == NL80211_IFTYPE_STATION)
 		ieee80211_mgd_stop_link(link);
 
+	cancel_delayed_work_sync(&link->color_collision_detect_work);
 	ieee80211_link_release_channel(link);
 }