gpiolib: fix off by one errors

The last gpio belonging to a chip is chip->base + chip->ngpios - 1.  Some
places in the code, but not all, forgot the critical minus one.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 7f138c6195ff..beaf6b3a37dc 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -127,7 +127,7 @@ int __init gpiochip_reserve(int start, int ngpio)
         unsigned long flags;
         int i;
 
-        if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio))
+        if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
                 return -EINVAL;
 
         spin_lock_irqsave(&gpio_lock, flags);
@@ -170,7 +170,7 @@ int gpiochip_add(struct gpio_chip *chip)
         unsigned        id;
         int             base = chip->base;
 
-        if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio))
+        if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
                         && base >= 0) {
                 status = -EINVAL;
                 goto fail;
@@ -207,7 +207,7 @@ fail:
         /* failures here can mean systems won't boot... */
         if (status)
                 pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
-                        chip->base, chip->base + chip->ngpio,
+                        chip->base, chip->base + chip->ngpio - 1,
                         chip->label ? : "generic");
         return status;
 }