[PATCH 11/22] gpiolib: cdev: remove recalculation of offset

From: Kent Gibson
Date: Tue Jun 23 2020 - 00:02:49 EST


Remove recalculation of offset from desc, where desc itself was calculated
from offset.

There is no benefit from for the desc -> hwgpio conversion in this
context. The only implicit benefit of the offset -> desc -> hwgpio is
the range check in the offset -> desc, but where desc is required you
still get that, and where desc isn't required it is simpler to perform
the range check directly.

Signed-off-by: Kent Gibson <warthog618@xxxxxxxxx>

---

drivers/gpio/gpiolib-cdev.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index a727709b24a9..b6878fc87dfc 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -834,7 +834,6 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
void __user *ip = (void __user *)arg;
struct gpio_desc *desc;
__u32 offset;
- int hwgpio;

/* We fail any subsequent ioctl():s when the chip is gone */
if (!gc)
@@ -862,12 +861,11 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
return -EFAULT;

+ /* this doubles as a range check on line_offset */
desc = gpiochip_get_desc(gc, lineinfo.line_offset);
if (IS_ERR(desc))
return PTR_ERR(desc);

- hwgpio = gpio_chip_hwgpio(desc);
-
gpio_desc_to_lineinfo(desc, &lineinfo);

if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
@@ -883,13 +881,12 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
return -EFAULT;

+ /* this doubles as a range check on line_offset */
desc = gpiochip_get_desc(gc, lineinfo.line_offset);
if (IS_ERR(desc))
return PTR_ERR(desc);

- hwgpio = gpio_chip_hwgpio(desc);
-
- if (test_and_set_bit(hwgpio, gcdev->watched_lines))
+ if (test_and_set_bit(lineinfo.line_offset, gcdev->watched_lines))
return -EBUSY;

gpio_desc_to_lineinfo(desc, &lineinfo);
@@ -902,13 +899,10 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (copy_from_user(&offset, ip, sizeof(offset)))
return -EFAULT;

- desc = gpiochip_get_desc(gc, offset);
- if (IS_ERR(desc))
- return PTR_ERR(desc);
-
- hwgpio = gpio_chip_hwgpio(desc);
+ if (offset >= gcdev->gdev->ngpio)
+ return -EINVAL;

- if (!test_and_clear_bit(hwgpio, gcdev->watched_lines))
+ if (!test_and_clear_bit(offset, gcdev->watched_lines))
return -EBUSY;

return 0;
--
2.27.0