linux-kernel - Re: [PATCH 2/2] usb_serial: only allow sysrq on a console port

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Date:	Mon, 6 Jul 2009 00:56:24 -0400
From:	Mike Frysinger <vapier.adi@...il.com>
To:	Robin Getz <rgetz@...ckfin.uclinux.org>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>, greg@...ah.com,
	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH 2/2] usb_serial: only allow sysrq on a console port

On Mon, Jul 6, 2009 at 00:38, Robin Getz wrote:
> On Sun 5 Jul 2009 14:17, Alan Cox pondered:
>> > If Jason's patch is necessary () - should this be fixed up for
>> > standard UARTs too?
>>
>> I think so yes, although I'd not realised it wasn't protected currently
>> ?
>
> Hmm - try as I may - I can't get this to fail - so it must be protected
> somewhere....
>
> Ahh---
>
> It is in include/linux/serial_core.h:uart_handle_break() - never checked the
> header for the magic before I bugged you... sorry about that...
>
>> > The above patch would sync the (seemlying duplicated) code between
>> > drivers/usb/serial/generic.c and include/linux/serial_core.h
>>
>> There is a lot of near duplicate code like this. That is one reason for
>> adding struct tty_port. In theory both could be collapsed into
>>
>>       int tty_port_handle_sysrq(struct tty_port *port, unsigned int ch)
>>       {
>>       }
>>
>> at this point as both USB and serial layer UARTs now have a port object.
>> That would just need port->sysrq collapsing into the tty_port.
>> port->console sort of already is.
>
> It appears that the usb serial doesn't handle breaks like serial_core does. (I
> don't see any support for SAK in usb_serial either?)
>
> Maybe _that_ is the real problem that Jason is trying to work around???

perhaps, but what Jason proposed originally sounds pretty sane.  if i
enable sysrq support on my desktop, i dont want some development board
being able to send a sysrq request back over my serial port and
rebooting my desktop.
-mike
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