Re: [PATCH v5 1/3] driver-core: return EINVAL error instead of BUG_ON()

[Greg Kroah-Hartman]

On Wed, May 16, 2018 at 06:08:14PM +0200, Florian Schmaus wrote:
> I triggerd the BUG_ON() in driver_register() when booting a domU Xen
> domain. Since there was no contextual information logged, I needed to
> attach kgdb to determine the culprit (the wmi-bmof driver in my
> case). The BUG_ON() was added in commit f48f3febb2cb ("driver-core: do
> not register a driver with bus_type not registered").
> 
> Instead of running into a BUG_ON() we print an error message
> identifying the, likely faulty, driver but continue booting.
> 
> Signed-off-by: Florian Schmaus <flo@xxxxxxxxxxxx>
> ---
> 
> Notes:
>     - Do not split long strings across lines.
> 
>  drivers/base/driver.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
> index ba912558a510..16b81d1c6cb7 100644
> --- a/drivers/base/driver.c
> +++ b/drivers/base/driver.c
> @@ -148,7 +148,11 @@ int driver_register(struct device_driver *drv)
>  	int ret;
>  	struct device_driver *other;
>  
> -	BUG_ON(!drv->bus->p);
> +	if (!drv->bus->p) {
> +		pr_err("Driver '%s' was unable to register with bus_type '%s' because it was not initialized.\n",

The bus is not initialized, not the driver, right?  This kind of makes
it sound the other way around :(

thanks,

greg k-h