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SubjectRe: [PATCH 2/2] tty: serial: 8250_core: Check that port->line is >=0
On 01/15/2015 03:55 PM, Michal Simek wrote:
> This patch should be the part of:
> "tty: serial: 8250_core: use the ->line argument as a hint in
> serial8250_find_match_or_unused()"
> (sha1: 59b3e898ddfc81a65975043b5eb44103cc29ff6e)
>
> port->line can be setup by DT driver to -1 which needs to
> be also checked.

This is what I have in 8250_omap to make sure it does not get < 0:

if (pdev->dev.of_node) {
ret = of_alias_get_id(pdev->dev.of_node, "serial");

of_property_read_u32(pdev->dev.of_node, "clock-frequency",
&up.port.uartclk);
priv->wakeirq = irq_of_parse_and_map(pdev->dev.of_node, 1);
} else {
ret = pdev->id;
}
if (ret < 0) {
dev_err(&pdev->dev, "failed to get alias/pdev id\n");
return ret;
}
up.port.line = ret;

but I didn't think of that others might pass < 0 since it wasn't used
before.
Does the original patch (you noted) break anything as of now? Because
then this patch should go stable.

> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

> ---
>
> I have similar patch to 59b3e898ddfc81a65975043b5eb44103cc29ff6e
> in xilinx tree for a while and port->line can be -1.
>
> The second part of this also should be (what other drivers do)
> reading aliases via of_alias_get_id() in of_serial.c:of_platform_serial_probe()
> which setup port.line.

Which second part?
Hmmm. You could use of_alias_get_id(port.dev->of_node, "serial") here,
correct. But I think additionally, since it won't work for the
non-DT devices like pure platform devices.

> ---
> drivers/tty/serial/8250/8250_core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
> index 65e52c9109e2..aab765177763 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -3512,7 +3512,8 @@ static struct uart_8250_port *serial8250_find_match_or_unused(struct uart_port *
>
> /* try line number first if still available */
> i = port->line;
> - if (i < nr_uarts && serial8250_ports[i].port.type == PORT_UNKNOWN &&
> + if (i >= 0 && i < nr_uarts &&
> + serial8250_ports[i].port.type == PORT_UNKNOWN &&
> serial8250_ports[i].port.iobase == 0)
> return &serial8250_ports[i];
> /*
> --
> 1.8.2.3

Sebastian


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