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

[Cornelia Huck <cohuck@redhat.com>]

On Mon, Jun 14 2021, Christoph Hellwig <hch@lst.de> wrote:

> From: Jason Gunthorpe <jgg@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@nvidia.com>
> [hch: drop the extra checks in device_driver_attach and bind_store]
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/base/bus.c |  2 +-
>  drivers/base/dd.c  | 32 ++++++++++----------------------
>  2 files changed, 11 insertions(+), 23 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>