linux-kernel - [66/89] USB: cdc-wdm: call wake_up_all to allow driver to shutdown on device removal

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Message-Id: <20120201210049.705813938@clark.kroah.org>
Date:	Wed, 01 Feb 2012 13:00:30 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Bjørn Mork <bjorn@...k.no>,
	Oliver Neukum <oliver@...kum.org>
Subject: [66/89] USB: cdc-wdm: call wake_up_all to allow driver to shutdown on device removal

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

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

From: Bjørn Mork <bjorn@...k.no>

commit 62aaf24dc125d7c55c93e313d15611f152b030c7 upstream.

wdm_disconnect() waits for the mutex held by wdm_read() before
calling wake_up_all().  This causes a deadlock, preventing device removal
to complete.  Do the wake_up_all() before we start waiting for the locks.

Signed-off-by: Bjørn Mork <bjorn@...k.no>
Cc: Oliver Neukum <oliver@...kum.org>
Cc: stable <stable@...r.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/class/cdc-wdm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -786,13 +786,13 @@ static void wdm_disconnect(struct usb_in
 	/* to terminate pending flushes */
 	clear_bit(WDM_IN_USE, &desc->flags);
 	spin_unlock_irqrestore(&desc->iuspin, flags);
+	wake_up_all(&desc->wait);
 	mutex_lock(&desc->rlock);
 	mutex_lock(&desc->wlock);
 	kill_urbs(desc);
 	cancel_work_sync(&desc->rxwork);
 	mutex_unlock(&desc->wlock);
 	mutex_unlock(&desc->rlock);
-	wake_up_all(&desc->wait);
 	if (!desc->count)
 		cleanup(desc);
 	mutex_unlock(&wdm_mutex);


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