[Intel-gfx] [PATCH 01/10] driver core: Pull required checks into driver_probe_device()

[Greg Kroah-Hartman]

On Mon, Jun 14, 2021 at 05:08:37PM +0200, Christoph Hellwig wrote:
> From: Jason Gunthorpe <jgg at nvidia.com>
> 
> Checking if the dev is dead or if the dev is already bound is a required
> precondition to invoking driver_probe_device(). All the call chains
> leading here duplicate these checks.
> 
> Add it directly to driver_probe_device() so the precondition is clear and
> remove the checks from device_driver_attach() and
> __driver_attach_async_helper().
> 
> The other call chain going through __device_attach_driver() does have
> these same checks but they are inlined into logic higher up the call stack
> and can't be removed.
> 
> The sysfs uAPI call chain starting at bind_store() is a bit confused
> because it reads dev->driver unlocked and returns -ENODEV if it is !NULL,
> otherwise it reads it again under lock and returns 0 if it is !NULL. Fix
> this to always return -EBUSY and always read dev->driver under its lock.
> 
> Done in preparation for the next patches which will add additional
> callers to driver_probe_device() and will need these checks as well.
> 
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> [hch: drop the extra checks in device_driver_attach and bind_store]
> Signed-off-by: Christoph Hellwig <hch at lst.de>

Reviewed-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>