[PATCH v6 3/4] driver core: shut down devices asynchronously

[Christoph Hellwig]

On Thu, May 16, 2024 at 10:49:19AM -0500, Stuart Hayes wrote:
> Add /sys/kernel/async_shutdown to allow user control of this feature:
> 
>   safe: shut down all devices synchronously, unless driver prefers async
> 	shutdown (driver opt-in) (default)
>   on:	shut down all devices asynchronously, unless disabled by the driver
> 	(driver opt-out)
>   off:	shut down all devices synchronously

The on option seems very odd.  IMHO safe is the only really sensible
option, and maybe we have to support off as a bandaid due to userspace
behavior dependent on synchronous shutdown, but I'd rather try even
without that first.