[PATCH] driver core: fix async device shutdown hang

[stuart hayes]

On 9/17/2024 3:42 PM, Greg Kroah-Hartman wrote:
> On Tue, Sep 17, 2024 at 03:15:17PM -0500, Stuart Hayes wrote:
>> Modify device_shutdown() so that supplier devices do not wait for
>> consumer devices to be shut down first when the devlink is sync state
>> only, since the consumer is not dependent on the supplier in this case.
>>
>> Without this change, a circular dependency could hang the system.
>>
>> Signed-off-by: Stuart Hayes <stuart.w.hayes at gmail.com>
> 
> What commit id does this fix?  Should it go to stable?
> 
> And what driver is causing this problem, is this a regression or for
> something new that just got added to the tree?
> 
> thanks,
> 
> greg k-h

This fixes commit 8064952c65045f05ee2671fe437770e50c151776, in
driver-core-next & linux-next... it's problem with code that was just
added to the tree (in drivers/base/core.c).  It is not in stable.

Apologies, I should have mentioned that from the start.

The issue was found using qemu... a pl061 device (supplier) and
gpio-keys device (consumer), from a qemu-generated device tree with
the aarch64 architecture.  I don't know why the devlink is in the
sync_state_only state in this case.  I didn't dig into that, because
I figured the shutdown code shouldn't hang regardless.