usb: ulpi: don't register drivers if bus doesn't exist

ULPI registers its 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-existent 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 <[email protected]>

Signed-off-by Heikki Krogerus <[email protected]>

Signed-off-by Lu Baolu <[email protected]>

Reported-by Zhuo Qiuxu <[email protected]>

Reviewed-by David Cohen <[email protected]>

---
  drivers/usb/common/ulpi.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

drivers/usb/common/ulpi.c +5 -1

index 0e6f968..af52b46 100644
@@ -132,6 +132,10 @@ int ulpi_register_driver(struct ulpi_driver *drv)
  	if (!drv->probe)
  		return -EINVAL;
 
+	/* Was the bus registered successfully? */
+	if (unlikely(WARN_ON(!ulpi_bus.p)))
+		return -ENODEV;
+
  	drv->driver.bus = &ulpi_bus;
 
  	return driver_register(&drv->driver);

@@ -242,7 +246,7 @@ static int __init ulpi_init(void)
  {
  	return bus_register(&ulpi_bus);
  }
-module_init(ulpi_init);
+subsys_initcall(ulpi_init);
 
  static void __exit ulpi_exit(void)
  {

Hi Heikki, Sasha and others,

Please ignore this patch. I should not squash these two patches into one and sign it off behalf of other people. I apologize for this and I'm sorry if this lets
you feel affronted.

ULPI registers its 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-existent 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 <[email protected]>

Signed-off-by Heikki Krogerus <[email protected]>

Signed-off-by Lu Baolu <[email protected]>

Reported-by Zhuo Qiuxu <[email protected]>

Reviewed-by David Cohen <[email protected]>

---
 drivers/usb/common/ulpi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

drivers/usb/common/ulpi.c +0 -0

index 0e6f968..af52b46 100644