[PATCH] bus: sunxi-rsb: fix usage_count leak when autosuspend_delay is negative

[PATCH] bus: sunxi-rsb: fix usage_count leak when autosuspend_delay is negative

[Guangshuo Li]

sunxi_rsb_probe() calls pm_runtime_use_autosuspend(), but
sunxi_rsb_remove() does not call the matching
pm_runtime_dont_use_autosuspend() before disabling runtime PM.

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.

Add the missing pm_runtime_dont_use_autosuspend() call before disabling
runtime PM.

This issue was found by manual code inspection.

Fixes: 4a0dbc12e618 ("bus: sunxi-rsb: Implement runtime power management")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/bus/sunxi-rsb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index daf0ea563e47..cd4c857756cf 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -815,6 +815,7 @@ static void sunxi_rsb_remove(struct platform_device *pdev)
 	struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
 
 	device_for_each_child(rsb->dev, NULL, sunxi_rsb_remove_devices);
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	sunxi_rsb_hw_exit(rsb);
 }
-- 
2.43.0

Re: [PATCH] bus: sunxi-rsb: fix usage_count leak when autosuspend_delay is negative

[Johan Hovold]

On Sat, Aug 08, 2026 at 02:20:29PM +0800, Guangshuo Li wrote:
> sunxi_rsb_probe() calls pm_runtime_use_autosuspend(), but
> sunxi_rsb_remove() does not call the matching
> pm_runtime_dont_use_autosuspend() before disabling runtime PM.
> 
> 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 disabling
> runtime PM.
> 
> This issue was found by manual code inspection.
> 
> Fixes: 4a0dbc12e618 ("bus: sunxi-rsb: Implement runtime power management")
> Cc: stable@vger.kernel.org
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>

Johan