[PATCH] SYSFS: add module referencing to sysfs attribute files.

fs/sysfs/file.c

@@ -247,6 +247,12 @@ static int check_perm(struct inode * inode, struct file * file)
 	if (!kobj || !attr)
 		goto Einval;
 
+	/* Grab the module reference for this attribute if we have one */
+	if (!try_module_get(attr->owner)) {
+		error = -ENODEV;
+		goto Done;
+	}
+
 	/* if the kobject has no ktype, then we assume that it is a subsystem
 	 * itself, and use ops for it.
 	 */
@@ -300,6 +306,7 @@ static int check_perm(struct inode * inode, struct file * file)
 	goto Done;
  Eaccess:
 	error = -EACCES;
+	module_put(attr->owner);
  Done:
 	if (error && kobj)
 		kobject_put(kobj);
@@ -314,10 +321,12 @@ static int sysfs_open_file(struct inode * inode, struct file * filp)
 static int sysfs_release(struct inode * inode, struct file * filp)
 {
 	struct kobject * kobj = filp->f_dentry->d_parent->d_fsdata;
+	struct attribute * attr = filp->f_dentry->d_fsdata;
 	struct sysfs_buffer * buffer = filp->private_data;
 
 	if (kobj) 
 		kobject_put(kobj);
+	module_put(attr->owner);
 
 	if (buffer) {
 		if (buffer->page)

include/linux/device.h

@@ -18,6 +18,7 @@
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/ioport.h>
+#include <linux/module.h>
 #include <asm/semaphore.h>
 #include <asm/atomic.h>
 
@@ -95,7 +96,7 @@ struct bus_attribute {
 
 #define BUS_ATTR(_name,_mode,_show,_store)	\
 struct bus_attribute bus_attr_##_name = { 		\
-	.attr = {.name = __stringify(_name), .mode = _mode },	\
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
 	.show	= _show,				\
 	.store	= _store,				\
 };
@@ -136,7 +137,7 @@ struct driver_attribute {
 
 #define DRIVER_ATTR(_name,_mode,_show,_store)	\
 struct driver_attribute driver_attr_##_name = { 		\
-	.attr = {.name = __stringify(_name), .mode = _mode },	\
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
 	.show	= _show,				\
 	.store	= _store,				\
 };
@@ -176,7 +177,7 @@ struct class_attribute {
 
 #define CLASS_ATTR(_name,_mode,_show,_store)			\
 struct class_attribute class_attr_##_name = { 			\
-	.attr = {.name = __stringify(_name), .mode = _mode },	\
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
 	.show	= _show,					\
 	.store	= _store,					\
 };
@@ -226,7 +227,7 @@ struct class_device_attribute {
 
 #define CLASS_DEVICE_ATTR(_name,_mode,_show,_store)		\
 struct class_device_attribute class_device_attr_##_name = { 	\
-	.attr = {.name = __stringify(_name), .mode = _mode },	\
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
 	.show	= _show,					\
 	.store	= _store,					\
 };
@@ -324,7 +325,7 @@ struct device_attribute {
 
 #define DEVICE_ATTR(_name,_mode,_show,_store) \
 struct device_attribute dev_attr_##_name = { 		\
-	.attr = {.name = __stringify(_name), .mode = _mode },	\
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
 	.show	= _show,				\
 	.store	= _store,				\
 };

include/linux/sysfs.h

@@ -10,9 +10,11 @@
 #define _SYSFS_H_
 
 struct kobject;
+struct module;
 
 struct attribute {
 	char			* name;
+	struct module 		* owner;
 	mode_t			mode;
 };