From: Felix Fietkau <nbd@openwrt.org>
Date: Thu, 13 Nov 2014 18:29:26 +0100
Subject: [PATCH] ath9k: do not access hardware on IRQs during reset

Instead of killing interrupts during reset when the first one happens,
kill them before issuing the reset.
This fixes an easy to reproduce crash with multiple cards sharing the
same IRQ.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---

--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -512,16 +512,13 @@ irqreturn_t ath_isr(int irq, void *dev)
 	if (!ah || test_bit(ATH_OP_INVALID, &common->op_flags))
 		return IRQ_NONE;
 
-	/* shared irq, not for us */
+	if (test_bit(ATH_OP_HW_RESET, &common->op_flags))
+		return IRQ_NONE;
 
+	/* shared irq, not for us */
 	if (!ath9k_hw_intrpend(ah))
 		return IRQ_NONE;
 
-	if (test_bit(ATH_OP_HW_RESET, &common->op_flags)) {
-		ath9k_hw_kill_interrupts(ah);
-		return IRQ_HANDLED;
-	}
-
 	/*
 	 * Figure out the reason(s) for the interrupt.  Note
 	 * that the hal returns a pseudo-ISR that may include
@@ -613,6 +610,7 @@ int ath_reset(struct ath_softc *sc, stru
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
 	int r;
 
+	ath9k_hw_kill_interrupts(sc->sc_ah);
 	set_bit(ATH_OP_HW_RESET, &common->op_flags);
 
 	ath9k_ps_wakeup(sc);
@@ -633,6 +631,7 @@ void ath9k_queue_reset(struct ath_softc 
 #ifdef CPTCFG_ATH9K_DEBUGFS
 	RESET_STAT_INC(sc, type);
 #endif
+	ath9k_hw_kill_interrupts(sc->sc_ah);
 	set_bit(ATH_OP_HW_RESET, &common->op_flags);
 	ieee80211_queue_work(sc->hw, &sc->hw_reset_work);
 }