device_schedule_callback() needs a module reference
This patch (as896b) fixes an oversight in the design of
device_schedule_callback(). It is necessary to acquire a reference to the
module owning the callback routine, to prevent the module from being
unloaded before the callback can run.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Satyam Sharma <satyam.sharma@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index fc46333..db0413a 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -633,6 +633,7 @@
struct kobject *kobj;
void (*func)(void *);
void *data;
+ struct module *owner;
struct work_struct work;
};
@@ -643,6 +644,7 @@
(ss->func)(ss->data);
kobject_put(ss->kobj);
+ module_put(ss->owner);
kfree(ss);
}
@@ -651,6 +653,7 @@
* @kobj: object we're acting for.
* @func: callback function to invoke later.
* @data: argument to pass to @func.
+ * @owner: module owning the callback code
*
* sysfs attribute methods must not unregister themselves or their parent
* kobject (which would amount to the same thing). Attempts to do so will
@@ -663,20 +666,25 @@
* until @func returns.
*
* Returns 0 if the request was submitted, -ENOMEM if storage could not
- * be allocated.
+ * be allocated, -ENODEV if a reference to @owner isn't available.
*/
int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
- void *data)
+ void *data, struct module *owner)
{
struct sysfs_schedule_callback_struct *ss;
+ if (!try_module_get(owner))
+ return -ENODEV;
ss = kmalloc(sizeof(*ss), GFP_KERNEL);
- if (!ss)
+ if (!ss) {
+ module_put(owner);
return -ENOMEM;
+ }
kobject_get(kobj);
ss->kobj = kobj;
ss->func = func;
ss->data = data;
+ ss->owner = owner;
INIT_WORK(&ss->work, sysfs_schedule_callback_work);
schedule_work(&ss->work);
return 0;