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gpiolib: don't check the retval of get_direction() when registering a chip

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During chip registration we should neither check the return value of
gc->get_direction() nor hold the SRCU lock when calling it. The former
is because pin controllers may have pins set to alternate functions and
return errors from their get_direction() callbacks. That's alright - we
should default to the safe INPUT state and not bail-out. The latter is
not needed because we haven't registered the chip yet so there's nothing
to protect against dynamic removal. In fact: we currently hit a lockdep
splat. Revert to calling the gc->get_direction() callback directly and
*not* checking its value.

Fixes: 9d846b1aeb ("gpiolib: check the return value of gpio_chip::get_direction()")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Closes: https://lore.kernel.org/all/81f890fc-6688-42f0-9756-567efc8bb97a@samsung.com/
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20250226-retval-fixes-v2-1-c8dc57182441@linaro.org
Tested-by: Gene C <arch@sapience.com>
Link: https://lore.kernel.org/r/20250311175631.83779-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski
2025-03-11 18:56:31 +01:00
parent 80e54e8491
commit 0102fbf52b
1 changed files with 11 additions and 16 deletions
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27
drivers/gpio/gpiolib.c
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@@ -1056,24 +1056,19 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
desc->gdev = gdev;
if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index)) {
ret = gc->get_direction(gc, desc_index);
if (ret < 0)
/*
* FIXME: Bail-out here once all GPIO drivers
* are updated to not return errors in
* situations that can be considered normal
* operation.
*/
dev_warn(&gdev->dev,
"%s: get_direction failed: %d\n",
__func__, ret);
assign_bit(FLAG_IS_OUT, &desc->flags, !ret);
} else {
/*
* We would typically want to check the return value of
* get_direction() here but we must not check the return value
* and bail-out as pin controllers can have pins configured to
* alternate functions and return -EINVAL. Also: there's no
* need to take the SRCU lock here.
*/
if (gc->get_direction && gpiochip_line_is_valid(gc, desc_index))
assign_bit(FLAG_IS_OUT, &desc->flags,
!gc->get_direction(gc, desc_index));
else
assign_bit(FLAG_IS_OUT,
&desc->flags, !gc->direction_input);
}
}
ret = of_gpiochip_add(gc);