From 362432aed5e5b497a8cf7b20c268ba71df93c045 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Sat, 9 Feb 2013 09:41:49 +0000 Subject: [PATCH] gpiolib: Fix locking on gpio debugfs files The debugfs files really need to hold the gpiolib spinlock before accessing the list. Otherwise chip addition/removal will cause an oops. Cc: Alexandre Courbot Cc: Linus Walleij Signed-off-by: Grant Likely --- drivers/gpio/gpiolib.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 5050693..4b3f388 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2053,29 +2053,35 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip) static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos) { + unsigned long flags; struct gpio_chip *chip = NULL; loff_t index = *pos; - /* REVISIT this isn't locked against gpio_chip removal ... */ - s->private = ""; + spin_lock_irqsave(&gpio_lock, flags); list_for_each_entry(chip, &gpio_chips, list) - if (index-- == 0) + if (index-- == 0) { + spin_unlock_irqrestore(&gpio_lock, flags); return chip; + } + spin_unlock_irqrestore(&gpio_lock, flags); return NULL; } static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos) { + unsigned long flags; struct gpio_chip *chip = v; void *ret = NULL; + spin_lock_irqsave(&gpio_lock, flags); if (list_is_last(&chip->list, &gpio_chips)) ret = NULL; else ret = list_entry(chip->list.next, struct gpio_chip, list); + spin_unlock_irqrestore(&gpio_lock, flags); s->private = "\n"; ++*pos; -- 2.7.4