[PATCH 2/5] serial: expose buf_overrun count through proc interface

[Greg Kroah-Hartman]

On Wed, Mar 21, 2018 at 10:52:38AM +0800, Jeremy Kerr wrote:
> The buf_overrun count is only every written, and not exposed to
> userspace anywhere. This means that dropped characters due to flip
> buffer overruns are never visible to userspace.
> 
> The /proc/tty/driver/serial file exports a bunch of metrics (including
> hardware overruns) already, so add the buf_overrun (as "bo:") to this
> file.
> 
> Signed-off-by: Jeremy Kerr <jk at ozlabs.org>
> ---
>  drivers/tty/serial/serial_core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 8f3dfc8b5307..fc677534b510 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1780,6 +1780,8 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
>  			seq_printf(m, " brk:%d", uport->icount.brk);
>  		if (uport->icount.overrun)
>  			seq_printf(m, " oe:%d", uport->icount.overrun);
> +		if (uport->icount.buf_overrun)
> +			seq_printf(m, " bo:%d", uport->icount.buf_overrun);

Hopefully this doesn't break any tools that might want to parse this
file :)