Hello.
When I am trying to use the serial
port, I am getting the machine lockup.
This started to happen sometime in a
2.6.9 era I think, and is not fixed
in the latest 2.6.11 pre's.
The bug looks trivial, unless I am
missing something. "port.lock" is
acquired in serial8250_interrupt()
and later in uart_start(), and that's
where the system is dead.
The calltrace is as follows:
serial8250_interrupt->!spin_lock(port.lock)!->serial8250_handle_port->
receive_chars->tty_flip_buffer_push->flush_to_ldisc->n_tty_receive_buf->
uart_flush_chars->uart_start->!spin_lock(port.lock)!->deadlock:(
Attached is a quick works-for-me fix
that just releases the lock at one
point. Can someone please have a look
into it and see if the other ser drivers
needs the same (or another) treatment?
Well, I can understand that the legacy
ser ports may not be too popular these
days, but then it is a local DoS, so it
may still be worth having a look.
I'll very much appreciate if the serial
port is to work again. I am still using
it, really! :)
On Llu, 2005-02-07 at 20:30, Stas Sergeev wrote:
> Hello.
>
> When I am trying to use the serial
> port, I am getting the machine lockup.
> This started to happen sometime in a
> 2.6.9 era I think, and is not fixed
> in the latest 2.6.11 pre's.
Known bug, just nobody has bothered to fix it. Please send the fix to
Linus so it gets into 2.6.11
On Mon, Feb 21, 2005 at 03:03:32PM +0000, Alan Cox wrote:
> Known bug, just nobody has bothered to fix it. Please send the fix to
> Linus so it gets into 2.6.11
Alan,
The fix was submitted to and accepted by Linus on Feb 8th. Therefore,
there's nothing to "bother" with.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
<><>
<><><>Hello.
Russell King wrote:
>> Known bug, just nobody has bothered to fix it. Please send the fix to
>> Linus so it gets into 2.6.11
> The fix was submitted to and accepted by Linus on Feb 8th. Therefore,
> there's nothing to "bother" with.
I've seen that fix in the latest -mm
patch released shortly after I wrote
the original message, but I can't help
feeling that the other serial drivers
have the same bug. I can see the very
same code in the au1x00_uart.c and other
files too, and it doesn't look like the
fix affected those.
I wasn't dare to ask, but now since also
Alan is bothered - can you please confirm
the other drivers are safe?
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