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Subject[PATCH] gpiolib: cdev: fix frame size warning in gpio_ioctl()
Date
The kernel test robot reports the following warning in [1]:

drivers/gpio/gpiolib-cdev.c: In function 'gpio_ioctl':
>>drivers/gpio/gpiolib-cdev.c:1437:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Refactor gpio_ioctl() to handle each ioctl in its own helper function
and so reduce the variables stored on the stack to those explicitly
required to service the ioctl at hand.

The lineinfo_get_v1() helper handles both the GPIO_GET_LINEINFO_IOCTL
and GPIO_GET_LINEINFO_WATCH_IOCTL, as per the corresponding v2
implementation - lineinfo_get().

[1] https://lore.kernel.org/lkml/202012270910.VW3qc1ER-lkp@intel.com/

Fixes: aad955842d1c ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
drivers/gpio/gpiolib-cdev.c | 145 ++++++++++++++++++------------------
1 file changed, 73 insertions(+), 72 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 12b679ca552c..1a7b51163528 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1979,6 +1979,21 @@ struct gpio_chardev_data {
#endif
};

+static int chipinfo_get(struct gpio_chardev_data *cdev, void __user *ip)
+{
+ struct gpio_device *gdev = cdev->gdev;
+ struct gpiochip_info chipinfo;
+
+ memset(&chipinfo, 0, sizeof(chipinfo));
+
+ strscpy(chipinfo.name, dev_name(&gdev->dev), sizeof(chipinfo.name));
+ strscpy(chipinfo.label, gdev->label, sizeof(chipinfo.label));
+ chipinfo.lines = gdev->ngpio;
+ if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
+ return -EFAULT;
+ return 0;
+}
+
#ifdef CONFIG_GPIO_CDEV_V1
/*
* returns 0 if the versions match, else the previously selected ABI version
@@ -1993,6 +2008,41 @@ static int lineinfo_ensure_abi_version(struct gpio_chardev_data *cdata,

return abiv;
}
+
+static int lineinfo_get_v1(struct gpio_chardev_data *cdev, void __user *ip,
+ bool watch)
+{
+ struct gpio_desc *desc;
+ struct gpioline_info lineinfo;
+ struct gpio_v2_line_info lineinfo_v2;
+
+ if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
+ return -EFAULT;
+
+ /* this doubles as a range check on line_offset */
+ desc = gpiochip_get_desc(cdev->gdev->chip, lineinfo.line_offset);
+ if (IS_ERR(desc))
+ return PTR_ERR(desc);
+
+ if (watch) {
+ if (lineinfo_ensure_abi_version(cdev, 1))
+ return -EPERM;
+
+ if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
+ return -EBUSY;
+ }
+
+ gpio_desc_to_lineinfo(desc, &lineinfo_v2);
+ gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
+
+ if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
+ if (watch)
+ clear_bit(lineinfo.line_offset, cdev->watched_lines);
+ return -EFAULT;
+ }
+
+ return 0;
+}
#endif

static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
@@ -2030,6 +2080,22 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
return 0;
}

+static int lineinfo_unwatch(struct gpio_chardev_data *cdev, void __user *ip)
+{
+ __u32 offset;
+
+ if (copy_from_user(&offset, ip, sizeof(offset)))
+ return -EFAULT;
+
+ if (offset >= cdev->gdev->ngpio)
+ return -EINVAL;
+
+ if (!test_and_clear_bit(offset, cdev->watched_lines))
+ return -EBUSY;
+
+ return 0;
+}
+
/*
* gpio_ioctl() - ioctl handler for the GPIO chardev
*/
@@ -2037,80 +2103,24 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct gpio_chardev_data *cdev = file->private_data;
struct gpio_device *gdev = cdev->gdev;
- struct gpio_chip *gc = gdev->chip;
void __user *ip = (void __user *)arg;
- __u32 offset;

/* We fail any subsequent ioctl():s when the chip is gone */
- if (!gc)
+ if (!gdev->chip)
return -ENODEV;

/* Fill in the struct and pass to userspace */
if (cmd == GPIO_GET_CHIPINFO_IOCTL) {
- struct gpiochip_info chipinfo;
-
- memset(&chipinfo, 0, sizeof(chipinfo));
-
- strscpy(chipinfo.name, dev_name(&gdev->dev),
- sizeof(chipinfo.name));
- strscpy(chipinfo.label, gdev->label,
- sizeof(chipinfo.label));
- chipinfo.lines = gdev->ngpio;
- if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
- return -EFAULT;
- return 0;
+ return chipinfo_get(cdev, ip);
#ifdef CONFIG_GPIO_CDEV_V1
- } else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
- struct gpio_desc *desc;
- struct gpioline_info lineinfo;
- struct gpio_v2_line_info lineinfo_v2;
-
- 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);
-
- gpio_desc_to_lineinfo(desc, &lineinfo_v2);
- gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
-
- if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
- return -EFAULT;
- return 0;
} else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
return linehandle_create(gdev, ip);
} else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
return lineevent_create(gdev, ip);
- } else if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
- struct gpio_desc *desc;
- struct gpioline_info lineinfo;
- struct gpio_v2_line_info lineinfo_v2;
-
- 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);
-
- if (lineinfo_ensure_abi_version(cdev, 1))
- return -EPERM;
-
- if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
- return -EBUSY;
-
- gpio_desc_to_lineinfo(desc, &lineinfo_v2);
- gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
-
- if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
- clear_bit(lineinfo.line_offset, cdev->watched_lines);
- return -EFAULT;
- }
-
- return 0;
+ } else if (cmd == GPIO_GET_LINEINFO_IOCTL ||
+ cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
+ return lineinfo_get_v1(cdev, ip,
+ cmd == GPIO_GET_LINEINFO_WATCH_IOCTL);
#endif /* CONFIG_GPIO_CDEV_V1 */
} else if (cmd == GPIO_V2_GET_LINEINFO_IOCTL ||
cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
@@ -2119,16 +2129,7 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
} else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
return linereq_create(gdev, ip);
} else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
- if (copy_from_user(&offset, ip, sizeof(offset)))
- return -EFAULT;
-
- if (offset >= cdev->gdev->ngpio)
- return -EINVAL;
-
- if (!test_and_clear_bit(offset, cdev->watched_lines))
- return -EBUSY;
-
- return 0;
+ return lineinfo_unwatch(cdev, ip);
}
return -EINVAL;
}
--
2.29.2
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