ath9k: disable the tasklet before taking the PCU lock

Fixes a reported CPU soft lockup where the tasklet tries to acquire the
lock and blocks while ath_prepare_reset (holding the lock) waits for it
to complete.

Cc: stable@vger.kernel.org
Reported-by: Robert Shade <robert.shade@gmail.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 9844b75..3796e65 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -196,16 +196,12 @@ static bool ath_prepare_reset(struct ath_softc *sc, bool retry_tx)
        ath9k_debug_samp_bb_mac(sc);
        ath9k_hw_disable_interrupts(ah);
 
-       tasklet_disable(&sc->intr_tq);
-
        if (!ath_stoprecv(sc))
                ret = false;
 
        if (!ath_drain_all_txq(sc, retry_tx))
                ret = false;
 
-       tasklet_enable(&sc->intr_tq);
-
        return ret;
 }
 
@@ -262,6 +258,7 @@ static int ath_reset_internal(struct ath_softc *sc, struct ath9k_channel *hchan,
 
        __ath_cancel_work(sc);
 
+       tasklet_disable(&sc->intr_tq);
        spin_lock_bh(&sc->sc_pcu_lock);
 
        if (!(sc->hw->conf.flags & IEEE80211_CONF_OFFCHANNEL)) {
@@ -296,6 +293,8 @@ static int ath_reset_internal(struct ath_softc *sc, struct ath9k_channel *hchan,
 
 out:
        spin_unlock_bh(&sc->sc_pcu_lock);
+       tasklet_enable(&sc->intr_tq);
+
        return r;
 }