Messages in this thread | | | Date | Tue, 27 Jul 2021 13:42:20 +0200 | From | Uwe Kleine-König <> | Subject | Re: [PATCH 1/5] nubus: Simplify check in remove callback |
| |
On Tue, Jul 27, 2021 at 07:50:39PM +1000, Finn Thain wrote: > On Tue, 27 Jul 2021, Uwe Kleine-König wrote: > > > The driver core only calls a remove callback when the device was > > successfully bound (aka probed) before. So dev->driver is never NULL. > > Are you sure dev->driver is non-NULL for the lifetime of the device? > A quick glance at device_reprobe() makes me wonder about that.
Not for the lifetime of the device, but as long as a driver is bound to the device. device_reprobe() calls device_driver_detach() after which the driver is considered unbound and dev->driver is assigned NULL. (via device_driver_detach -> device_release_driver_internal -> __device_release_driver)
> > Apart from that, the compiler might already assume dev->driver being > > non-NULL after to_nubus_driver(dev->driver) was called. > > I don't understand how a compiler can make that assumption. But then, I > don't know why compilers do a lot of the things they do...
Ah, you're right, there is no dereference in container_of, so I might also be wrong here. I will send a v2 without this last sentence in the commit log.
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [unhandled content-type:application/pgp-signature] | |