Re: [PATCH] [DRIVER MODEL] Fix depca

[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/net/depca.c b/drivers/net/depca.c
--- a/drivers/net/depca.c
+++ b/drivers/net/depca.c
@@ -1470,15 +1470,6 @@ static int __init depca_mca_probe(struct
 ** ISA bus I/O device probe
 */
 
-static void depca_platform_release (struct device *device)
-{
-	struct platform_device *pldev;
-
-	/* free device */
-	pldev = to_platform_device (device);
-	kfree (pldev);
-}
-
 static void __init depca_platform_probe (void)
 {
 	int i;
@@ -1491,19 +1482,16 @@ static void __init depca_platform_probe 
 		 * line, use it (if valid) */
 		if (io && io != depca_io_ports[i].iobase)
 			continue;
-		
-		if (!(pldev = kmalloc (sizeof (*pldev), GFP_KERNEL)))
+
+		pldev = platform_device_alloc(depca_string, i);
+		if (!pldev)
 			continue;
 
-		memset (pldev, 0, sizeof (*pldev));
-		pldev->name = depca_string;
-		pldev->id   = i;
 		pldev->dev.platform_data = (void *) depca_io_ports[i].iobase;
-		pldev->dev.release       = depca_platform_release;
 		depca_io_ports[i].device = pldev;
 
-		if (platform_device_register (pldev)) {
-			kfree (pldev);
+		if (platform_device_add(pldev)) {
+			platform_device_put(pldev);
 			depca_io_ports[i].device = NULL;
 			continue;
 		}
@@ -1515,6 +1503,7 @@ static void __init depca_platform_probe 
 		 * allocated structure */
 			
 			depca_io_ports[i].device = NULL;
+			pldev->dev.platform_data = NULL;
 			platform_device_unregister (pldev);
 		}
 	}
@@ -2112,6 +2101,7 @@ static void __exit depca_module_exit (vo
 
 	for (i = 0; depca_io_ports[i].iobase; i++) {
 		if (depca_io_ports[i].device) {
+			depca_io_ports[i].device->dev.platform_data = NULL;
 			platform_device_unregister (depca_io_ports[i].device);
 			depca_io_ports[i].device = NULL;
 		}


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