Re: [PATCH] bus: mhi: host: pci_generic: fix usage_count leak when autosuspend_delay is negative

[Johan Hovold]

On Sat, Aug 08, 2026 at 02:29:16PM +0800, Guangshuo Li wrote:
> mhi_pci_probe() calls pm_runtime_use_autosuspend() when runtime PM is
> supported, but mhi_pci_remove() does not call the matching
> pm_runtime_dont_use_autosuspend() during device removal.
> 
> If the autosuspend delay is set to a negative value while autosuspend
> is enabled, the runtime PM core increments usage_count to prevent
> runtime suspend. Without calling pm_runtime_dont_use_autosuspend()
> during driver teardown, this reference is not dropped and usage_count
> remains unbalanced.

As I've explained elsewhere, this is just misleading. There is no usage
count leak here as the count is balanced whenever the user re-enables
autosuspend through sysfs (by writing a non-negative timeout).

Drivers should clean up after themselves and disable autosuspend, but
this is more of a clean up than a fix and should not be backported.

You've sent upwards of 60 of these in the matter of just a few days,
some of which have even been picked up. Please send follow-ups (replies
or v2s) as soon as possible to prevent further of these from getting
merged.

> Add the missing pm_runtime_dont_use_autosuspend() call before
> forbidding runtime PM.
> 
> This issue was found by manual code inspection.
> 
> Fixes: d3800c1dce24 ("bus: mhi: pci_generic: Add support for runtime PM")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>

Johan