gpiolib: don't call sleeping functions with a spinlock taken (6409d049) · Commits · 戴 / test

We must not call pinctrl_gpio_can_use_line() with the gpio_lock taken as it takes a mutex internally. Let's move the call before taking the spinlock and store the return value. This isn't perfect - there's a moment between calling pinctrl_gpio_can_use_line() and taking the spinlock where the situation can change but it isn't a regression either: previously this part wasn't protected at all and it only affects the information user-space is seeing. Reported-by:

Geert Uytterhoeven <geert@linux-m68k.org> Fixes: ("gpiolib: provide a dedicated function for setting lineinfo") Signed-off-by:

Bartosz Golaszewski <bgolaszewski@baylibre.com> Acked-by:

Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -1158,8 +1158,19 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
		struct gpioline_info *info)
		{
		struct gpio_chip *gc = desc->gdev->chip;
		bool ok_for_pinctrl;
		unsigned long flags;

		/*
		* This function takes a mutex so we must check this before taking
		* the spinlock.
		*
		* FIXME: find a non-racy way to retrieve this information. Maybe a
		* lock common to both frameworks?
		*/
		ok_for_pinctrl =
		pinctrl_gpio_can_use_line(gc->base + info->line_offset);

		spin_lock_irqsave(&gpio_lock, flags);

		if (desc->name) {
		@@ -1186,7 +1197,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
		test_bit(FLAG_USED_AS_IRQ, &desc->flags) \|\|
		test_bit(FLAG_EXPORT, &desc->flags) \|\|
		test_bit(FLAG_SYSFS, &desc->flags) \|\|
		!pinctrl_gpio_can_use_line(gc->base + info->line_offset))
		!ok_for_pinctrl)
		info->flags \|= GPIOLINE_FLAG_KERNEL;
		if (test_bit(FLAG_IS_OUT, &desc->flags))
		info->flags \|= GPIOLINE_FLAG_IS_OUT;

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