linux-kernel - [ 41/89] ath9k: disable the tasklet before taking the PCU lock

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Message-Id: <20130201130210.458915965@linuxfoundation.org>
Date:	Fri,  1 Feb 2013 14:07:56 +0100
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Robert Shade <robert.shade@...il.com>,
	Felix Fietkau <nbd@...nwrt.org>,
	"John W. Linville" <linville@...driver.com>
Subject: [ 41/89] ath9k: disable the tasklet before taking the PCU lock

3.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <nbd@...nwrt.org>

commit 4668cce527acb3bd048c5e6c99b157a14b214671 upstream.

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.

Reported-by: Robert Shade <robert.shade@...il.com>
Signed-off-by: Felix Fietkau <nbd@...nwrt.org>
Signed-off-by: John W. Linville <linville@...driver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/ath/ath9k/main.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -195,16 +195,12 @@ static bool ath_prepare_reset(struct ath
 	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;
 }
 
@@ -261,6 +257,7 @@ static int ath_reset_internal(struct ath
 
 	__ath_cancel_work(sc);
 
+	tasklet_disable(&sc->intr_tq);
 	spin_lock_bh(&sc->sc_pcu_lock);
 
 	if (!(sc->hw->conf.flags & IEEE80211_CONF_OFFCHANNEL)) {
@@ -291,6 +288,8 @@ static int ath_reset_internal(struct ath
 
 out:
 	spin_unlock_bh(&sc->sc_pcu_lock);
+	tasklet_enable(&sc->intr_tq);
+
 	return r;
 }
 


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