ath9k: serialize ath9k_hw_setpower calls

Because ath9k_setpower is called from various contexts, we have to
protect it against concurrent calls.

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/hw.c

@@ -2728,7 +2728,8 @@ static bool ath9k_hw_set_power_awake(struct ath_hw *ah, int setChip)
 	return true;
 }
 
-bool ath9k_hw_setpower(struct ath_hw *ah, enum ath9k_power_mode mode)
+static bool ath9k_hw_setpower_nolock(struct ath_hw *ah,
+				     enum ath9k_power_mode mode)
 {
 	int status = true, setChip = true;
 	static const char *modes[] = {
@@ -2762,6 +2763,18 @@ bool ath9k_hw_setpower(struct ath_hw *ah, enum ath9k_power_mode mode)
 	return status;
 }
 
+bool ath9k_hw_setpower(struct ath_hw *ah, enum ath9k_power_mode mode)
+{
+	unsigned long flags;
+	bool ret;
+
+	spin_lock_irqsave(&ah->ah_sc->sc_pm_lock, flags);
+	ret = ath9k_hw_setpower_nolock(ah, mode);
+	spin_unlock_irqrestore(&ah->ah_sc->sc_pm_lock, flags);
+
+	return ret;
+}
+
 /*
  * Helper for ASPM support.
  *