Re: [PATCH 1/2] PM: runtime: Fix I/O hang due to race between resume and runtime disable

[Bart Van Assche <bvanassche@acm.org>]

On 12/1/25 10:47 AM, Rafael J. Wysocki wrote:
> Generally speaking, if blk_queue_enter() or __bio_queue_enter() may
> run in parallel with device_suspend_late() for q->dev, the driver of
> that device is defective, because it is responsible for preventing
> this situation from happening.  The most straightforward way to
> achieve that is to provide a .suspend() callback for q->dev that will
> runtime-resume it (and, of course, q->dev will need to be prepared for
> system suspend as appropriate after that).

Isn't the suspend / hibernation order such that no block I/O is
submitted while block devices transition to a lower power state? I'm
surprised to read that individual drivers are responsible for preventing
that blk_queue_enter() or __bio_queue_enter() run concurrently with
device_suspend_late().

Regarding the UFSHCI driver: if a UFS controller is already runtime
suspended, we want it to remain suspended during system suspend.

Thanks,

Bart.