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

[stuart hayes]

On 5/28/2024 1:31 AM, Christoph Hellwig wrote:
> 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.
> 

I added the option because of comments from Greg K-H on the v4 submission
of this patch--see

https://lore.kernel.org/lkml/2023102151-rejoicing-studio-6126@gregkh/T/#m5d0459480bc0fda4563040cab2036839bcbb79a8).

I thought it would be nice to have the option for testing, even if it gets
removed later, but I'll certainly remove it now if necessary.