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gpiolib: allocate memory atomically with a spinlock held 

We will eventually switch to protecting the GPIO descriptors with a mutex
but until then, we need to allocate memory for the label copy atomically
while we're holding the global spinlock.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-gpio/62588146-eed6-42f7-ba26-160226b109fe@moroto.mountain/T/#u
Fixes: f8d05e276b ("gpiolib: remove gpiochip_is_requested()")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2023-12-12 11:55:01 +01:00
parent d22f93c6a0
commit 0a10d10781
1 changed files with 9 additions and 1 deletions
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10
drivers/gpio/gpiolib.c
View File

@ -2399,7 +2399,15 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
if (!test_bit(FLAG_REQUESTED, &desc->flags))
return NULL;
label = kstrdup(desc->label, GFP_KERNEL);
/*
* FIXME: Once we mark gpiod_direction_input/output() and
* gpiod_get_direction() with might_sleep(), we'll be able to protect
* the GPIO descriptors with mutex (while value setting operations will
* become lockless).
*
* Until this happens, this allocation needs to be atomic.
*/
label = kstrdup(desc->label, GFP_ATOMIC);
if (!label)
return ERR_PTR(-ENOMEM);