linux-kernel - [09/27] p54spi: Fix workqueue deadlock

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Message-Id: <20111207165601.179828005@clark.kroah.org>
Date:	Wed, 07 Dec 2011 08:54:42 -0800
From:	Greg KH <gregkh@...e.de>
To:	<linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Cc:	<torvalds@...ux-foundation.org>, <akpm@...ux-foundation.org>,
	<alan@...rguk.ukuu.org.uk>, Michael Buesch <m@...s.ch>,
	Christian Lamparter <chunkeey@...glemail.com>,
	"John W. Linville" <linville@...driver.com>
Subject: [09/27] p54spi: Fix workqueue deadlock

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: =?UTF-8?q?Michael=20B=C3=BCsch?= <m@...s.ch>

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: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/net/wireless/p54/p54spi.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/p54/p54spi.c
+++ b/drivers/net/wireless/p54/p54spi.c
@@ -581,8 +581,6 @@ static void p54spi_op_stop(struct ieee80
 
 	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);
@@ -590,6 +588,8 @@ static void p54spi_op_stop(struct ieee80
 
 	priv->fw_state = FW_STATE_OFF;
 	mutex_unlock(&priv->mutex);
+
+	cancel_work_sync(&priv->work);
 }
 
 static int __devinit p54spi_probe(struct spi_device *spi)


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