On Wed, Mar 04, 2015 at 05:59:45PM +0000, Andre Przywara wrote:
> Although we care about not unregistering the driver if there are
> still ports connected during the .remove callback, we do miss this
> check in the pl011_probe function. So if the current port allocation
> fails, but there are other ports already registered, we will kill
> those.
> So factor out the port removal into a separate function and use that
> in the probe function, too.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> drivers/tty/serial/amba-pl011.c | 38 +++++++++++++++++++++-----------------
> 1 file changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 92783fc..961f9b0 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -2235,6 +2235,24 @@ static int pl011_probe_dt_alias(int index, struct device *dev)
> return ret;
> }
>
> +/* unregisters the driver also if no more ports are left */
> +static void pl011_unregister_port(struct uart_amba_port *uap)
> +{
> + int i;
> + bool busy = false;
> +
> + for (i = 0; i < ARRAY_SIZE(amba_ports); i++) {
> + if (amba_ports[i] == uap)
> + amba_ports[i] = NULL;
> + else if (amba_ports[i])
> + busy = true;
> + }
> + pl011_dma_remove(uap);
> + if (!busy)
> + uart_unregister_driver(&amba_reg);
> +}
This is still racy, as I pointed out at the time this crap was dreamt
up.
There is _no_ locking between an individual driver's ->probe or ->remove
functions being called concurrently for different devices. The only
locking which the driver model guarantees is that a single struct device
can only be probed by one driver at a time.
Multiple struct device's can be in-progress of ->probe or ->remove
simultaneously.
However, this isn't your bug to solve... it's those who were proponents
of this crap approach.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
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