Re: [PATCH] usb: ulpi: don't register drivers if bus doesn't exist

Greg KH
2015-05-24T07:19:50Z

On Wed, May 20, 2015 at 03:33:26PM -0400, Sasha Levin wrote:
> ULPI registers it's bus at module_init so if the bus fails to register, the
> module will fail to load and all will be well in the world.
>
> However, if the ULPI code is built-in rather than a module, the bus
> initialization may fail but we'd still try to register drivers later onto
> a non-existant bus, which will panic the kernel.
>
> Fix that by checking that the bus was indeed initialized before trying to
> register drivers on top of it.
>
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
> drivers/usb/common/ulpi.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/common/ulpi.c b/drivers/usb/common/ulpi.c
> index 0e6f968..0b0a5e7 100644
> --- a/drivers/usb/common/ulpi.c
> +++ b/drivers/usb/common/ulpi.c
> @@ -132,6 +132,10 @@ int ulpi_register_driver(struct ulpi_driver *drv)
> if (!drv->probe)
> return -EINVAL;
>
> + /* Was the bus registered successfully? */
> + if (!ulpi_bus.p)
> + return -ENODEV;

Ick, no, don't go mucking around in the bus internals like this, that's
not ok. You should either "know" the bus is registered, or something is
really wrong with the design here.

greg k-h