staging: wfx: call wfx_do_unjoin() synchronously

Currently, wfx_do_unjoin() are called by the mean of work queues.
However, the contexts from where they are called are not atomic. So
there is no reason to not call it synchronously.

This change will simplify the code. Notice two main changes:
   - There no more reason to lock tx queue before to run
     wfx_do_unjoin(). We can lock the tx queue directly from
     wfx_do_unjoin().
   - Most of the time, wfx_do_unjoin_work() was called with conf_mutex
     held. This patch remove lock of conf_mutex in wfx_do_unjoin_work()
     and ensure that conf_mutex is always held whatever the context.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200410133239.438347-4-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/sta.c

@@ -354,14 +354,12 @@ static void wfx_event_handler_work(struct work_struct *work)
 	list_for_each_entry(event, &list, link) {
 		switch (event->evt.event_id) {
 		case HIF_EVENT_IND_BSSLOST:
-			cancel_work_sync(&wvif->unjoin_work);
 			mutex_lock(&wvif->scan_lock);
 			wfx_cqm_bssloss_sm(wvif, 1, 0, 0);
 			mutex_unlock(&wvif->scan_lock);
 			break;
 		case HIF_EVENT_IND_BSSREGAINED:
 			wfx_cqm_bssloss_sm(wvif, 0, 0, 0);
-			cancel_work_sync(&wvif->unjoin_work);
 			break;
 		case HIF_EVENT_IND_RCPI_RSSI:
 			wfx_event_report_rssi(wvif,
@@ -401,21 +399,20 @@ static void wfx_bss_params_work(struct work_struct *work)
 	mutex_unlock(&wvif->wdev->conf_mutex);
 }
 
+// Call it with wdev->conf_mutex locked
 static void wfx_do_unjoin(struct wfx_vif *wvif)
 {
-	mutex_lock(&wvif->wdev->conf_mutex);
-
 	if (!wvif->state)
-		goto done;
+		return;
 
 	if (wvif->state == WFX_STATE_AP)
-		goto done;
+		return;
 
 	cancel_work_sync(&wvif->update_filtering_work);
 	wvif->state = WFX_STATE_PASSIVE;
 
 	/* Unjoin is a reset. */
-	wfx_tx_flush(wvif->wdev);
+	wfx_tx_lock_flush(wvif->wdev);
 	hif_keep_alive_period(wvif, 0);
 	hif_reset(wvif, false);
 	wfx_tx_policy_init(wvif);
@@ -430,9 +427,7 @@ static void wfx_do_unjoin(struct wfx_vif *wvif)
 	wvif->disable_beacon_filter = false;
 	wfx_update_filtering(wvif);
 	memset(&wvif->bss_params, 0, sizeof(wvif->bss_params));
-
-done:
-	mutex_unlock(&wvif->wdev->conf_mutex);
+	wfx_tx_unlock(wvif->wdev);
 }
 
 static void wfx_set_mfp(struct wfx_vif *wvif,
@@ -476,6 +471,7 @@ static void wfx_do_join(struct wfx_vif *wvif)
 	int ssidlen = 0;
 
 	wfx_tx_lock_flush(wvif->wdev);
+	mutex_lock(&wvif->wdev->conf_mutex);
 
 	if (wvif->state)
 		wfx_do_unjoin(wvif);
@@ -484,12 +480,11 @@ static void wfx_do_join(struct wfx_vif *wvif)
 			       conf->bssid, NULL, 0,
 			       IEEE80211_BSS_TYPE_ANY, IEEE80211_PRIVACY_ANY);
 	if (!bss && !conf->ibss_joined) {
+		mutex_unlock(&wvif->wdev->conf_mutex);
 		wfx_tx_unlock(wvif->wdev);
 		return;
 	}
 
-	mutex_lock(&wvif->wdev->conf_mutex);
-
 	/* Sanity check beacon interval */
 	if (!wvif->beacon_int)
 		wvif->beacon_int = 1;
@@ -515,16 +510,13 @@ static void wfx_do_join(struct wfx_vif *wvif)
 	if (ret) {
 		ieee80211_connection_loss(wvif->vif);
 		wvif->join_complete_status = -1;
-		/* Tx lock still held, unjoin will clear it. */
-		if (!schedule_work(&wvif->unjoin_work))
-			wfx_tx_unlock(wvif->wdev);
+		wfx_do_unjoin(wvif);
 	} else {
 		wvif->join_complete_status = 0;
 		if (wvif->vif->type == NL80211_IFTYPE_ADHOC)
 			wvif->state = WFX_STATE_IBSS;
 		else
 			wvif->state = WFX_STATE_PRE_STA;
-		wfx_tx_unlock(wvif->wdev);
 
 		/* Upload keys */
 		wfx_upload_keys(wvif);
@@ -535,18 +527,10 @@ static void wfx_do_join(struct wfx_vif *wvif)
 		 * receives at least one
 		 */
 		wvif->disable_beacon_filter = true;
+		wfx_update_filtering(wvif);
 	}
-	wfx_update_filtering(wvif);
-
-	mutex_unlock(&wvif->wdev->conf_mutex);
-}
-
-static void wfx_unjoin_work(struct work_struct *work)
-{
-	struct wfx_vif *wvif = container_of(work, struct wfx_vif, unjoin_work);
-
-	wfx_do_unjoin(wvif);
 	wfx_tx_unlock(wvif->wdev);
+	mutex_unlock(&wvif->wdev->conf_mutex);
 }
 
 int wfx_sta_add(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
@@ -672,7 +656,6 @@ static void wfx_join_finalize(struct wfx_vif *wvif,
 		hif_dual_cts_protection(wvif, false);
 
 	wfx_cqm_bssloss_sm(wvif, 0, 0, 0);
-	cancel_work_sync(&wvif->unjoin_work);
 
 	wvif->bss_params.beacon_lost_count = 20;
 	wvif->bss_params.aid = info->aid;
@@ -754,10 +737,7 @@ void wfx_bss_info_changed(struct ieee80211_hw *hw,
 
 	if (changed & BSS_CHANGED_ASSOC && !info->assoc &&
 	    (wvif->state == WFX_STATE_STA || wvif->state == WFX_STATE_IBSS)) {
-		/* Shedule unjoin work */
-		wfx_tx_lock(wdev);
-		if (!schedule_work(&wvif->unjoin_work))
-			wfx_tx_unlock(wdev);
+		wfx_do_unjoin(wvif);
 	} else {
 		if (changed & BSS_CHANGED_BEACON_INT) {
 			if (info->ibss_joined)
@@ -999,7 +979,6 @@ int wfx_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
 	complete(&wvif->set_pm_mode_complete);
 	INIT_WORK(&wvif->update_filtering_work, wfx_update_filtering_work);
 	INIT_WORK(&wvif->bss_params_work, wfx_bss_params_work);
-	INIT_WORK(&wvif->unjoin_work, wfx_unjoin_work);
 	INIT_WORK(&wvif->tx_policy_upload_work, wfx_tx_policy_upload_work);
 
 	mutex_init(&wvif->scan_lock);
@@ -1039,9 +1018,7 @@ void wfx_remove_interface(struct ieee80211_hw *hw,
 	case WFX_STATE_PRE_STA:
 	case WFX_STATE_STA:
 	case WFX_STATE_IBSS:
-		wfx_tx_lock_flush(wdev);
-		if (!schedule_work(&wvif->unjoin_work))
-			wfx_tx_unlock(wdev);
+		wfx_do_unjoin(wvif);
 		break;
 	case WFX_STATE_AP:
 		/* reset.link_id = 0; */
@@ -1057,7 +1034,6 @@ void wfx_remove_interface(struct ieee80211_hw *hw,
 	hif_set_macaddr(wvif, NULL);
 
 	wfx_cqm_bssloss_sm(wvif, 0, 0, 0);
-	cancel_work_sync(&wvif->unjoin_work);
 	wfx_free_event_queue(wvif);
 
 	wdev->vif[wvif->id] = NULL;

drivers/staging/wfx/wfx.h

@@ -99,7 +99,6 @@ struct wfx_vif {
 	struct work_struct	bss_params_work;
 
 	int			join_complete_status;
-	struct work_struct	unjoin_work;
 
 	/* avoid some operations in parallel with scan */
 	struct mutex		scan_lock;