Re: [PATCH v5 09/13] gpio: mxc: use cleanup guard for pm_runtime_get_noresume() balance

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] pm: double put of usage counter due to no_free_ptr() self-assignment
--

commit f4335cfd7512992cdd6d3fcb1a49da9aabbb176c
Author: Peng Fan <peng.fan@nxp.com>

gpio: mxc: use cleanup guard for pm_runtime_get_noresume() balance

This commit replaces the manual pm_runtime_put_noidle() error path cleanup
with a __free scope-based guard in mxc_gpio_probe(). It also attempts to
disarm the guard on the success path before calling
pm_runtime_put_autosuspend().

> diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c
> index 5ae9cdee6424d..3d5a6566d3f43 100644
> --- a/drivers/gpio/gpio-mxc.c
> +++ b/drivers/gpio/gpio-mxc.c

[ ... ]

> @@ -556,6 +561,8 @@ static int mxc_gpio_probe(struct platform_device *pdev)
>  	mxc_update_irq_chained_handler(port, true);
>  
>  	platform_set_drvdata(pdev, port);
> +
> +	pm_guard = no_free_ptr(pm_guard);
>  	pm_runtime_put_autosuspend(dev);

[Severity: High]
Does this self-assignment defeat the no_free_ptr() cleanup inhibition,
causing a double-put of the usage counter?

Because no_free_ptr() is marked __must_check, assigning it back to the
same variable is a common attempt to silence compiler warnings. However,
no_free_ptr(pm_guard) internally sets pm_guard to NULL but evaluates to
the original pointer value.

By assigning the evaluated result back to pm_guard, the NULL value is
immediately overwritten with the original pointer, leaving the guard
armed.

When mxc_gpio_probe() returns successfully, the cleanup handler will execute
pm_runtime_put_noidle(dev) because pm_guard is still armed. Since this path
also explicitly calls pm_runtime_put_autosuspend(dev) right after the
assignment, will this result in the usage counter being decremented twice?

>  
>  	return 0;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261010-gpio-mxc-cleanup-v5-0-1e59e6ddfa00@nxp.com?part=9