# Re: \[PATCH 1/3\] Input: sysrq - drop tty argument from sysrq ops handlers

- From: Benjamin Herrenschmidt \<benh@kernel.crashing.org\>
- Date: 2010-08-04 08:34:26 
- List: linux-input
- Page: https://ratatoskr.run/linux-input/2010/08/3601152
- Thread: https://ratatoskr.run/linux-input/2010/08/3601139/t.md

```text
On Wed, 2010-08-04 at 00:59 -0700, Dmitry Torokhov wrote:
> Noone is using tty argument so let's get rid of it.

While talking about sysrq...

I noticed that serial drivers call sysrq with the uart lock held.

I've seen deadlocks caused by that, for example, when entering the
debugger, it waits forever for a CPU which is itself waiting on the UART
lock.

I have a patch to drop the lock in serial_core.h, I'll post that
tomorrow hopefully, just checking if there's any objection there ? The
serial drivers might need to be audited a bit to make sure they cope
with the lock being dropped and re-acquired around the sysrq call.

Cheers,
Ben.
 

```