gpio: convert linehandle_create() to FD_PREPARE()

Link: https://patch.msgid.link/20251123-work-fd-prepare-v4-38-b6efa1706cfd@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

drivers/gpio/gpiolib-cdev.c

@@ -298,12 +298,13 @@ static const struct file_operations linehandle_fileops = {
 #endif
 };
 
+DEFINE_FREE(linehandle_free, struct linehandle_state *, if (!IS_ERR_OR_NULL(_T)) linehandle_free(_T))
+
 static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 {
 	struct gpiohandle_request handlereq;
-	struct linehandle_state *lh;
-	struct file *file;
-	int fd, i, ret;
+	struct linehandle_state *lh __free(linehandle_free) = NULL;
+	int i, ret;
 	u32 lflags;
 
 	if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
@@ -327,10 +328,8 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 		lh->label = kstrndup(handlereq.consumer_label,
 				     sizeof(handlereq.consumer_label) - 1,
 				     GFP_KERNEL);
-		if (!lh->label) {
-			ret = -ENOMEM;
-			goto out_free_lh;
-		}
+		if (!lh->label)
+			return -ENOMEM;
 	}
 
 	lh->num_descs = handlereq.lines;
@@ -340,20 +339,18 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 		u32 offset = handlereq.lineoffsets[i];
 		struct gpio_desc *desc = gpio_device_get_desc(gdev, offset);
 
-		if (IS_ERR(desc)) {
-			ret = PTR_ERR(desc);
-			goto out_free_lh;
-		}
+		if (IS_ERR(desc))
+			return PTR_ERR(desc);
 
 		ret = gpiod_request_user(desc, lh->label);
 		if (ret)
-			goto out_free_lh;
+			return ret;
 		lh->descs[i] = desc;
 		linehandle_flags_to_desc_flags(handlereq.flags, &desc->flags);
 
 		ret = gpiod_set_transitory(desc, false);
 		if (ret < 0)
-			goto out_free_lh;
+			return ret;
 
 		/*
 		 * Lines have to be requested explicitly for input
@@ -364,11 +361,11 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 
 			ret = gpiod_direction_output_nonotify(desc, val);
 			if (ret)
-				goto out_free_lh;
+				return ret;
 		} else if (lflags & GPIOHANDLE_REQUEST_INPUT) {
 			ret = gpiod_direction_input_nonotify(desc);
 			if (ret)
-				goto out_free_lh;
+				return ret;
 		}
 
 		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
@@ -377,44 +374,23 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 			offset);
 	}
 
-	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
-	if (fd < 0) {
-		ret = fd;
-		goto out_free_lh;
-	}
+	FD_PREPARE(fdf, O_RDONLY | O_CLOEXEC,
+		   anon_inode_getfile("gpio-linehandle", &linehandle_fileops,
+				      lh, O_RDONLY | O_CLOEXEC));
+	if (fdf.err)
+		return fdf.err;
+	retain_and_null_ptr(lh);
 
-	file = anon_inode_getfile("gpio-linehandle",
-				  &linehandle_fileops,
-				  lh,
-				  O_RDONLY | O_CLOEXEC);
-	if (IS_ERR(file)) {
-		ret = PTR_ERR(file);
-		goto out_put_unused_fd;
-	}
-
-	handlereq.fd = fd;
-	if (copy_to_user(ip, &handlereq, sizeof(handlereq))) {
-		/*
-		 * fput() will trigger the release() callback, so do not go onto
-		 * the regular error cleanup path here.
-		 */
-		fput(file);
-		put_unused_fd(fd);
+	handlereq.fd = fd_prepare_fd(fdf);
+	if (copy_to_user(ip, &handlereq, sizeof(handlereq)))
 		return -EFAULT;
-	}
 
-	fd_install(fd, file);
+	fd_publish(fdf);
 
 	dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
 		lh->num_descs);
 
 	return 0;
-
-out_put_unused_fd:
-	put_unused_fd(fd);
-out_free_lh:
-	linehandle_free(lh);
-	return ret;
 }
 #endif /* CONFIG_GPIO_CDEV_V1 */