2012-06-22 13:24:11

by Chris Brannon

Subject: [PATCH] tty: keyboard.c: Remove locking from vt_get_leds.

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 <[email protected]>
---
drivers/tty/vt/keyboard.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 48cc6f2..770a854 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1049,13 +1049,10 @@ static int kbd_update_leds_helper(struct input_handle *handle, void *data)
*/
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;
}
--
1.7.10.4

2012-06-22 13:31:14

by Alan

Subject: Re: [PATCH] tty: keyboard.c: Remove locking from vt_get_leds.

On Fri, 22 Jun 2012 08:16:34 -0500
Christopher Brannon <[email protected]> wrote:

> 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 <[email protected]>

Acked-by: Alan Cox <[email protected]>