linux-kernel - [v2.6.34-stable 28/77] p54spi: Fix workqueue deadlock

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Message-ID: <1357688156-25387-29-git-send-email-paul.gortmaker@windriver.com>
Date:	Tue, 8 Jan 2013 18:35:07 -0500
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	<stable@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:	Michael Büsch <m@...s.ch>,
	"John W. Linville" <linville@...driver.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [v2.6.34-stable 28/77] p54spi: Fix workqueue deadlock

From: Michael Büsch <m@...s.ch>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 2d1618170eb493d18f66f2ac03775409a6fb97c6 upstream.

priv->work must not be synced while priv->mutex is locked, because
the mutex is taken in the work handler.
Move cancel_work_sync down to after the device shutdown code.
This is safe, because the work handler checks fw_state and bails out
early in case of a race.

Signed-off-by: Michael Buesch <m@...s.ch>
Acked-by: Christian Lamparter <chunkeey@...glemail.com>
Signed-off-by: John W. Linville <linville@...driver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/net/wireless/p54/p54spi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/p54/p54spi.c b/drivers/net/wireless/p54/p54spi.c
index 4cede24..8cf0301 100644
--- a/drivers/net/wireless/p54/p54spi.c
+++ b/drivers/net/wireless/p54/p54spi.c
@@ -582,8 +582,6 @@ static void p54spi_op_stop(struct ieee80211_hw *dev)
 
 	WARN_ON(priv->fw_state != FW_STATE_READY);
 
-	cancel_work_sync(&priv->work);
-
 	p54spi_power_off(priv);
 	spin_lock_irqsave(&priv->tx_lock, flags);
 	INIT_LIST_HEAD(&priv->tx_pending);
@@ -591,6 +589,8 @@ static void p54spi_op_stop(struct ieee80211_hw *dev)
 
 	priv->fw_state = FW_STATE_OFF;
 	mutex_unlock(&priv->mutex);
+
+	cancel_work_sync(&priv->work);
 }
 
 static int __devinit p54spi_probe(struct spi_device *spi)
-- 
1.7.12.1

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