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

David Cohen
2015-05-20T21:20:29Z

Hi,

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

A minor comment: s/it's/its/

> 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;
> +

Good catch. Otherwise it may trigger BUG() on driver_register().
I wonder if it would be nice to have a macro for that checking :)

Anyway,

Reviewed-by: David Cohen <david.a.cohen@linux.intel.com>

> drv->driver.bus = &ulpi_bus;
>
> return driver_register(&drv->driver);
> --
> 1.7.10.4
>