ath9k: serialize ath9k_ps_{wakeup,restore} calls

These functions are changing the power mode of the chip, but this may
have unpredictable effects, if another code are trying to set the power
mode via 'ath9k_hw_setpower' in the same time from another context.

Changes-licensed-under: ISC
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -576,7 +576,7 @@ struct ath_softc {
 	u32 keymax;
 	DECLARE_BITMAP(keymap, ATH_KEYMAX);
 	u8 splitmic;
-	atomic_t ps_usecount;
+	unsigned long ps_usecount;
 	enum ath9k_int imask;
 	enum ath9k_ht_extprotspacing ht_extprotspacing;
 	enum ath9k_ht_macmode tx_chan_width;

drivers/net/wireless/ath/ath9k/hw.c

@@ -2777,23 +2777,39 @@ bool ath9k_hw_setpower(struct ath_hw *ah, enum ath9k_power_mode mode)
 
 void ath9k_ps_wakeup(struct ath_softc *sc)
 {
-	if (atomic_inc_return(&sc->ps_usecount) == 1)
+	unsigned long flags;
+
+	spin_lock_irqsave(&sc->sc_pm_lock, flags);
+	if (++sc->ps_usecount != 1)
+		goto unlock;
+
 	if (sc->sc_ah->power_mode != ATH9K_PM_AWAKE) {
 		sc->sc_ah->restore_mode = sc->sc_ah->power_mode;
-			ath9k_hw_setpower(sc->sc_ah, ATH9K_PM_AWAKE);
+		ath9k_hw_setpower_nolock(sc->sc_ah, ATH9K_PM_AWAKE);
 	}
+
+ unlock:
+	spin_unlock_irqrestore(&sc->sc_pm_lock, flags);
 }
 
 void ath9k_ps_restore(struct ath_softc *sc)
 {
-	if (atomic_dec_and_test(&sc->ps_usecount))
+	unsigned long flags;
+
+	spin_lock_irqsave(&sc->sc_pm_lock, flags);
+	if (--sc->ps_usecount != 0)
+		goto unlock;
+
 	if ((sc->hw->conf.flags & IEEE80211_CONF_PS) &&
 		!(sc->sc_flags & (SC_OP_WAIT_FOR_BEACON |
 				SC_OP_WAIT_FOR_CAB |
 				SC_OP_WAIT_FOR_PSPOLL_DATA |
 				SC_OP_WAIT_FOR_TX_ACK)))
-			ath9k_hw_setpower(sc->sc_ah,
+		ath9k_hw_setpower_nolock(sc->sc_ah,
 				      sc->sc_ah->restore_mode);
+
+ unlock:
+	spin_unlock_irqrestore(&sc->sc_pm_lock, flags);
 }
 
 /*