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 <f...@geekplace.eu> --- Notes: - return EINVAL (instead of EBUSY) - follow common pattern when quoting commits in commit messages 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..afd5b08b7677 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) { + printk(KERN_ERR "Driver '%s' was unable to register bus_type\n", + drv->name); + return -EINVAL; + } if ((drv->bus->probe && drv->probe) || (drv->bus->remove && drv->remove) || -- 2.16.1