On Sun, Mar 06, 2016 at 08:40:10PM +0530, Sudip Mukherjee wrote:
> If the parport bus is not yet registered and any device using parallel
> port tries to register with the bus we get a stackdump with a message
> of Kernel bug.
>
> Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.2+
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@xxxxxxxxxxxxxxx>
> ---
>
> Hi Ross,
> Can you please test this patch in your setup. This is a respin of the
> previous patch in another way.
Yep, this also solves the issue for me.
Tested-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> drivers/parport/share.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/parport/share.c b/drivers/parport/share.c
> index 3308427..c1eba80 100644
> --- a/drivers/parport/share.c
> +++ b/drivers/parport/share.c
> @@ -135,9 +135,18 @@ static struct bus_type parport_bus_type = {
> .probe = parport_probe,
> };
>
> +static bool is_registered;
> +
> int parport_bus_init(void)
> {
> - return bus_register(&parport_bus_type);
> + int ret;
> +
> + ret = bus_register(&parport_bus_type);
> + if (ret)
> + return ret;
> +
> + is_registered = true;
> + return 0;
> }
>
> void parport_bus_exit(void)
> @@ -273,6 +282,9 @@ int __parport_register_driver(struct parport_driver *drv, struct module *owner,
> /* using device model */
> int ret;
>
> + if (!is_registered)
> + return -EAGAIN;
> +
> /* initialize common driver fields */
> drv->driver.name = drv->name;
> drv->driver.bus = &parport_bus_type;
> --
> 1.9.1
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