From: Bartosz Golaszewski <brgl@bgdev.pl>
Date: Mon, 16 Oct 2017 09:32:29 +0000 (+0200)
Subject: gpiolib: only check line handle flags once
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=418ee8e91fe7fc90ffb6bce391304e084f77bce4;p=linux.git

gpiolib: only check line handle flags once

There's no need to check the validity of handle request flags more
than once, right after copying the data from user. Move the check
out of the for loop and simplify the error path by bailing out before
allocating any resources.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ff46a1b6299e0..58196be52b1ef 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -444,12 +444,19 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 	struct linehandle_state *lh;
 	struct file *file;
 	int fd, i, ret;
+	u32 lflags;
 
 	if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
 		return -EFAULT;
 	if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX))
 		return -EINVAL;
 
+	lflags = handlereq.flags;
+
+	/* Return an error if an unknown flag is set */
+	if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
+		return -EINVAL;
+
 	lh = kzalloc(sizeof(*lh), GFP_KERNEL);
 	if (!lh)
 		return -ENOMEM;
@@ -470,7 +477,6 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 	/* Request each GPIO */
 	for (i = 0; i < handlereq.lines; i++) {
 		u32 offset = handlereq.lineoffsets[i];
-		u32 lflags = handlereq.flags;
 		struct gpio_desc *desc;
 
 		if (offset >= gdev->ngpio) {
@@ -478,12 +484,6 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 			goto out_free_descs;
 		}
 
-		/* Return an error if a unknown flag is set */
-		if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) {
-			ret = -EINVAL;
-			goto out_free_descs;
-		}
-
 		desc = &gdev->descs[offset];
 		ret = gpiod_request(desc, lh->label);
 		if (ret)