linux-kernel - [ 11/52] tty: keyboard.c: Remove locking from vt_get

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Message-Id: <20121004210636.753135044@linuxfoundation.org>
Date:	Thu,  4 Oct 2012 14:21:02 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk,
	Christopher Brannon <chris@...-brannons.com>,
	Alan Cox <alan@...ux.intel.com>
Subject: [ 11/52] tty: keyboard.c: Remove locking from vt_get_leds.

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

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

From: Christopher Brannon <chris@...-brannons.com>

commit 157a4b311c45c9aba75a990464d9680867dc8805 upstream.

There are three call sites for this function, and all three
are called within a keyboard handler.
kbd_event_lock is already held within keyboard handlers,
so attempting to lock it in vt_get_leds causes deadlock.

Signed-off-by: Christopher Brannon <chris@...-brannons.com>
Acked-by: Alan Cox <alan@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/vt/keyboard.c |    3 ---
 1 file changed, 3 deletions(-)

--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1053,13 +1053,10 @@ static int kbd_update_leds_helper(struct
  */
 int vt_get_leds(int console, int flag)
 {
-	unsigned long flags;
 	struct kbd_struct * kbd = kbd_table + console;
 	int ret;
 
-	spin_lock_irqsave(&kbd_event_lock, flags);
 	ret = vc_kbd_led(kbd, flag);
-	spin_unlock_irqrestore(&kbd_event_lock, flags);
 
 	return ret;
 }


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