Re: [PATCH v2 1/7] drivers/base: Introduce kill_device()

[Greg Kroah-Hartman]

On Wed, Jul 17, 2019 at 06:07:53PM -0700, Dan Williams wrote:
> The libnvdimm subsystem arranges for devices to be destroyed as a result
> of a sysfs operation. Since device_unregister() cannot be called from
> an actively running sysfs attribute of the same device libnvdimm
> arranges for device_unregister() to be performed in an out-of-line async
> context.
> 
> The driver core maintains a 'dead' state for coordinating its own racing
> async registration / de-registration requests. Rather than add local
> 'dead' state tracking infrastructure to libnvdimm device objects, export
> the existing state tracking via a new kill_device() helper.
> 
> The kill_device() helper simply marks the device as dead, i.e. that it
> is on its way to device_del(), or returns that the device was already
> dead. This can be used in advance of calling device_unregister() for
> subsystems like libnvdimm that might need to handle multiple user
> threads racing to delete a device.
> 
> This refactoring does not change any behavior, but it is a pre-requisite
> for follow-on fixes and therefore marked for -stable.
> 
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Fixes: 4d88a97aa9e8 ("libnvdimm, nvdimm: dimm driver and base libnvdimm device-driver...")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Tested-by: Jane Chu <jane.chu@xxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>