From 6409d049ce28bef35e13dfb8699fc7ee27469ba1 Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Fri, 17 Apr 2020 09:01:51 +0200 Subject: [PATCH] gpiolib: don't call sleeping functions with a spinlock taken 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 Fixes: d2ac25798208 ("gpiolib: provide a dedicated function for setting lineinfo") Signed-off-by: Bartosz Golaszewski Acked-by: Linus Walleij --- drivers/gpio/gpiolib.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 29f6abe..bf9732a 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -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; -- 2.7.4