wifi: rtw88: use work to update rate to avoid RCU warning

The ieee80211_ops::sta_rc_update must be atomic, because
ieee80211_chan_bw_change() holds rcu_read lock while calling
drv_sta_rc_update(), so create a work to do original things.

 Voluntary context switch within RCU read-side critical section!
 WARNING: CPU: 0 PID: 4621 at kernel/rcu/tree_plugin.h:318
 rcu_note_context_switch+0x571/0x5d0
 CPU: 0 PID: 4621 Comm: kworker/u16:2 Tainted: G        W  OE
 Workqueue: phy3 ieee80211_chswitch_work [mac80211]
 RIP: 0010:rcu_note_context_switch+0x571/0x5d0
 Call Trace:
  <TASK>
  __schedule+0xb0/0x1460
  ? __mod_timer+0x116/0x360
  schedule+0x5a/0xc0
  schedule_timeout+0x87/0x150
  ? trace_raw_output_tick_stop+0x60/0x60
  wait_for_completion_timeout+0x7b/0x140
  usb_start_wait_urb+0x82/0x160 [usbcore
  usb_control_msg+0xe3/0x140 [usbcore
  rtw_usb_read+0x88/0xe0 [rtw_usb
  rtw_usb_read8+0xf/0x10 [rtw_usb
  rtw_fw_send_h2c_command+0xa0/0x170 [rtw_core
  rtw_fw_send_ra_info+0xc9/0xf0 [rtw_core
  drv_sta_rc_update+0x7c/0x160 [mac80211
  ieee80211_chan_bw_change+0xfb/0x110 [mac80211
  ieee80211_change_chanctx+0x38/0x130 [mac80211
  ieee80211_vif_use_reserved_switch+0x34e/0x900 [mac80211
  ieee80211_link_use_reserved_context+0x88/0xe0 [mac80211
  ieee80211_chswitch_work+0x95/0x170 [mac80211
  process_one_work+0x201/0x410
  worker_thread+0x4a/0x3b0
  ? process_one_work+0x410/0x410
  kthread+0xe1/0x110
  ? kthread_complete_and_exit+0x20/0x20
  ret_from_fork+0x1f/0x30
  </TASK>

Cc: stable@vger.kernel.org
Fixes: c1edc864 ("rtw88: add ieee80211:sta_rc_update ops")
Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/linux-wireless/f1e31e8e-f84e-3791-50fb-663a83c5c6e9@lwfinger.net/T/#tSigned-off-by: Ping-Ke Shih <pkshih@realtek.com>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230508085429.46653-1-pkshih@realtek.com

drivers/net/wireless/realtek/rtw88/mac80211.c

@@ -918,7 +918,7 @@ static void rtw_ops_sta_rc_update(struct ieee80211_hw *hw,
 	struct rtw_sta_info *si = (struct rtw_sta_info *)sta->drv_priv;
 
 	if (changed & IEEE80211_RC_BW_CHANGED)
-		rtw_update_sta_info(rtwdev, si, true);
+		ieee80211_queue_work(rtwdev->hw, &si->rc_work);
 }
 
 const struct ieee80211_ops rtw_ops = {

drivers/net/wireless/realtek/rtw88/main.c

@@ -319,6 +319,17 @@ static u8 rtw_acquire_macid(struct rtw_dev *rtwdev)
 	return mac_id;
 }
 
+static void rtw_sta_rc_work(struct work_struct *work)
+{
+	struct rtw_sta_info *si = container_of(work, struct rtw_sta_info,
+					       rc_work);
+	struct rtw_dev *rtwdev = si->rtwdev;
+
+	mutex_lock(&rtwdev->mutex);
+	rtw_update_sta_info(rtwdev, si, true);
+	mutex_unlock(&rtwdev->mutex);
+}
+
 int rtw_sta_add(struct rtw_dev *rtwdev, struct ieee80211_sta *sta,
 		struct ieee80211_vif *vif)
 {
@@ -329,12 +340,14 @@ int rtw_sta_add(struct rtw_dev *rtwdev, struct ieee80211_sta *sta,
 	if (si->mac_id >= RTW_MAX_MAC_ID_NUM)
 		return -ENOSPC;
 
+	si->rtwdev = rtwdev;
 	si->sta = sta;
 	si->vif = vif;
 	si->init_ra_lv = 1;
 	ewma_rssi_init(&si->avg_rssi);
 	for (i = 0; i < ARRAY_SIZE(sta->txq); i++)
 		rtw_txq_init(rtwdev, sta->txq[i]);
+	INIT_WORK(&si->rc_work, rtw_sta_rc_work);
 
 	rtw_update_sta_info(rtwdev, si, true);
 	rtw_fw_media_status_report(rtwdev, si->mac_id, true);
@@ -353,6 +366,8 @@ void rtw_sta_remove(struct rtw_dev *rtwdev, struct ieee80211_sta *sta,
 	struct rtw_sta_info *si = (struct rtw_sta_info *)sta->drv_priv;
 	int i;
 
+	cancel_work_sync(&si->rc_work);
+
 	rtw_release_macid(rtwdev, si->mac_id);
 	if (fw_exist)
 		rtw_fw_media_status_report(rtwdev, si->mac_id, false);

drivers/net/wireless/realtek/rtw88/main.h

@@ -743,6 +743,7 @@ struct rtw_txq {
 DECLARE_EWMA(rssi, 10, 16);
 
 struct rtw_sta_info {
+	struct rtw_dev *rtwdev;
 	struct ieee80211_sta *sta;
 	struct ieee80211_vif *vif;
 
@@ -767,6 +768,8 @@ struct rtw_sta_info {
 
 	bool use_cfg_mask;
 	struct cfg80211_bitrate_mask *mask;
+
+	struct work_struct rc_work;
 };
 
 enum rtw_bfee_role {