Re: [PATCH] Bluetooth: btmtksdio: fix usage_count leak when autosuspend_delay is negative

[Johan Hovold <johan@kernel.org>]

On Fri, Aug 07, 2026 at 11:14:47PM +0800, Guangshuo Li wrote:
> btmtksdio_setup() calls pm_runtime_use_autosuspend() when runtime PM
> is supported, but btmtksdio_remove() does not call the matching
> pm_runtime_dont_use_autosuspend() when removing the device.
> 
> 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.

I noticed the bluetooth ones have already been picked up, but for the
record:

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 a just a few days,
some 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 in the remove
> path before restoring the runtime PM usage reference.
> 
> This issue was found by manual code inspection.
> 
> Fixes: 7f3c563c575e ("Bluetooth: btmtksdio: Add runtime PM support to SDIO based Bluetooth")
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
> ---
>  drivers/bluetooth/btmtksdio.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
> index c6f80c419e90..4e1012e90979 100644
> --- a/drivers/bluetooth/btmtksdio.c
> +++ b/drivers/bluetooth/btmtksdio.c
> @@ -1480,6 +1480,9 @@ static void btmtksdio_remove(struct sdio_func *func)
>  	if (test_bit(BTMTKSDIO_FUNC_ENABLED, &bdev->tx_state))
>  		btmtksdio_close(hdev);
>  
> +	if (bdev->data->pm_runtime_supported)
> +		pm_runtime_dont_use_autosuspend(bdev->dev);
> +
>  	/* Be consistent the state in btmtksdio_probe */
>  	pm_runtime_get_noresume(bdev->dev);

Johan