2023-08-14 11:47:28

by Andy Shevchenko

Subject: [PATCH v1 1/1] gpiolib: sysfs: Do unexport GPIO when user asks for it

It seems that sysfs interface implicitly relied on the gpiod_free()
to unexport the line. This is not good and prone to regressions.
Fix it by explicitly calling gpiod_unexport().

Fixes: b0ce9ce408b6 ("gpiolib: Do not unexport GPIO on freeing")
Reported-by: Marek Behún <[email protected]>
Closes: https://lore.kernel.org/r/20230808102828.4a9eac09@dellmb
Signed-off-by: Andy Shevchenko <[email protected]>
Tested-by: Marek Behún <[email protected]>
---
drivers/gpio/gpiolib-sysfs.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 530dfd19d7b5..50503a4525eb 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -515,8 +515,9 @@ static ssize_t unexport_store(const struct class *class,
* they may be undone on its behalf too.
*/
if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
+ gpiod_unexport(desc);
+ gpiod_free(desc);
status = 0;
- gpiod_free(desc);
}
done:
if (status)
@@ -781,8 +782,10 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
mutex_unlock(&sysfs_lock);

/* unregister gpiod class devices owned by sysfs */
- for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS)
+ for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
+ gpiod_unexport(desc);
gpiod_free(desc);
+ }
}

static int __init gpiolib_sysfs_init(void)
--
2.40.0.1.gaa8946217a0b

2023-08-19 08:35:14

by Andy Shevchenko

Subject: Re: [PATCH v1 1/1] gpiolib: sysfs: Do unexport GPIO when user asks for it

On Mon, Aug 14, 2023 at 7:13 PM Bartosz Golaszewski <[email protected]> wrote:
> On Mon, Aug 14, 2023 at 1:19 PM Andy Shevchenko
> <[email protected]> wrote:
> >
> > It seems that sysfs interface implicitly relied on the gpiod_free()
> > to unexport the line. This is not good and prone to regressions.
> > Fix it by explicitly calling gpiod_unexport().
> >
>
> I wouldn't say it's prone to regressions, it's literally just that
> gpiod_free() should not deal with sysfs.
>
> How about that for commit message (I can change it when applying):
>
> It seems that sysfs interface implicitly relied on the gpiod_free()
> to unexport the line. This is logically incorrect as core gpiolib should
> not deal with sysfs so instead of restoring it, let's call gpiod_unexport()
> from sysfs code.

I'm fine with it, go ahead and apply with the change. Thank you!

--
With Best Regards,
Andy Shevchenko