Re: [PATCH] [DRIVER MODEL] Fix arcfb

[Russell King <rmk+lkml@arm.linux.org.uk>]

Release code in driver modules is a potential cause of oopsen.
The device may be in use by a userspace process, which will keep
a reference to the device.  If the module is unloaded, the module
text will be freed.  Subsequently, when the last reference is
dropped, the release code will be called, which no longer exists.

Use generic platform device allocation/release code in modules.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/drivers/video/arcfb.c b/drivers/video/arcfb.c
--- a/drivers/video/arcfb.c
+++ b/drivers/video/arcfb.c
@@ -502,10 +502,6 @@ static ssize_t arcfb_write(struct file *
 	return err;
 }
 
-static void arcfb_platform_release(struct device *device)
-{
-}
-
 static struct fb_ops arcfb_ops = {
 	.owner		= THIS_MODULE,
 	.fb_open	= arcfb_open,
@@ -624,13 +620,7 @@ static struct device_driver arcfb_driver
 	.remove = arcfb_remove,
 };
 
-static struct platform_device arcfb_device = {
-	.name	= "arcfb",
-	.id	= 0,
-	.dev	= {
-		.release = arcfb_platform_release,
-	}
-};
+static struct platform_device *arcfb_device;
 
 static int __init arcfb_init(void)
 {
@@ -641,9 +631,16 @@ static int __init arcfb_init(void)
 
 	ret = driver_register(&arcfb_driver);
 	if (!ret) {
-		ret = platform_device_register(&arcfb_device);
-		if (ret)
+		arcfb_device = platform_device_alloc("arcfb", 0);
+		if (arcfb_device) {
+			ret = platform_device_add(arcfb_device);
+		} else {
+			ret = -ENOMEM;
+		}
+		if (ret) {
+			platform_device_put(arcfb_device);
 			driver_unregister(&arcfb_driver);
+		}
 	}
 	return ret;
 
@@ -651,7 +648,7 @@ static int __init arcfb_init(void)
 
 static void __exit arcfb_exit(void)
 {
-	platform_device_unregister(&arcfb_device);
+	platform_device_unregister(arcfb_device);
 	driver_unregister(&arcfb_driver);
 }
 


-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core