rtlwifi: rtl8723be: Fix potential race condition

Flag rfchange_inprogress in struct rtl_ps_ctl is protected by a spinlock
in most routines but not in rtl8723be_dm_watchdog(), which could
lead to a race condition. The necessary locking to prevent this condition
is added.

Reported-by: Pavel Andrianov <andrianov@ispras.ru>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Pavel Andrianov <andrianov@ispras.ru>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/rtl8723be/dm.c

@@ -1279,6 +1279,7 @@ void rtl8723be_dm_watchdog(struct ieee80211_hw *hw)
 	if (ppsc->p2p_ps_info.p2p_ps_mode)
 		fw_ps_awake = false;
 
+	spin_lock(&rtlpriv->locks.rf_ps_lock);
 	if ((ppsc->rfpwr_state == ERFON) &&
 		((!fw_current_inpsmode) && fw_ps_awake) &&
 		(!ppsc->rfchange_inprogress)) {
@@ -1294,5 +1295,6 @@ void rtl8723be_dm_watchdog(struct ieee80211_hw *hw)
 		rtl8723be_dm_check_txpower_tracking(hw);
 		rtl8723be_dm_dynamic_txpower(hw);
 	}
+	spin_unlock(&rtlpriv->locks.rf_ps_lock);
 	rtlpriv->dm.dbginfo.num_qry_beacon_pkt = 0;
 }