lkml.org 
[lkml]   [2022]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 5/5] serial/8250: Only use fifo after the port is initialized in console_write
On Wed, 16 Mar 2022, Wander Lairson Costa wrote:

> The serial driver set the value of uart_8250_port.fcr in the function
> serial8250_config_port, but only writes the value to the controller
> register later in the initalization code.
>
> That opens a small window in which is not safe to use the fifo for
> console write.
>
> Make sure the port is initialized correctly before reading the FCR
> cached value.
>
> Unfortunately, I lost track of who originally reported the issue. If
> s/he is reading this, please speak up so I can give you the due credit.
>
> Signed-off-by: Wander Lairson Costa <wander@redhat.com>
> ---
> drivers/tty/serial/8250/8250_port.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 4acf620be241..7e2227161555 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -3416,6 +3416,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
> !(up->capabilities & UART_CAP_MINI) &&
> up->tx_loadsz > 1 &&
> (up->fcr & UART_FCR_ENABLE_FIFO) &&
> + test_bit(TTY_PORT_INITIALIZED, &port->state->port.iflags) &&
> /*
> * After we put a data in the fifo, the controller will send
> * it regardless of the CTS state. Therefore, only use fifo

So it looks like 2-5 just contain your development history and should all
be merged to 1/5 (perhaps with Co-developed-by: tags where appropriate).

And please don't just merge them "silently" there w/o describing in the
message _why_ you ended up doing the things the way you did in the end.
The messages you've written for patches 2-5 will serve you as great source
material (with small mods, obviously).


--
i.

\
 
 \ /
  Last update: 2022-03-17 09:44    [W:0.130 / U:0.680 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site