Re: [PATCH v5 1/7] gpiolib: wait for pending label frees before cleaning up desc_srcu

[Andy Shevchenko]

On Tue, Nov 03, 2026 at 12:32:34PM +0200, Adrian Ambrozewicz wrote:
> desc_set_label() frees the old label with call_srcu() on
> gdev->desc_srcu, and gpiodev_release() calls synchronize_srcu() before
> cleanup_srcu_struct(). synchronize_srcu() waits for a grace period, not
> for queued callbacks. Once the srcu_struct uses per-CPU callback lists,
> a label freed by gpiochip_free_hogs() can still be pending, and
> cleanup_srcu_struct() warns:
> 
>   WARNING: kernel/rcu/srcutree.c:706 at cleanup_srcu_struct+0x239/0x330, CPU#0: init/1
>   Call Trace:
>    gpiodev_release
>    device_release
>    kobject_put
>    devres_release_all
>    device_release_driver_internal
>    platform_device_unregister
>    gpio_sim_device_deactivate
> 
> Use srcu_barrier(), which waits for them.
> 
> Reproduced with a hogged gpio-sim line, setting the chip live and back
> on a 4-CPU guest with srcutree.convert_to_big=1: it warns within 60
> cycles; with this change, 1000 cycles pass.

...

> Assisted-by: LLM

This tag is obsoleted. Instead explain under '---' how AI has been used to
generate this contribution.

-- 
With Best Regards,
Andy Shevchenko