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>
This commit is contained in:
Alan Stern 2007-04-26 00:12:04 -07:00 committed by Greg Kroah-Hartman
parent fa1a8c23eb
commit 523ded71de
4 changed files with 29 additions and 13 deletions

View file

@ -480,9 +480,10 @@ void device_remove_bin_file(struct device *dev, struct bin_attribute *attr)
EXPORT_SYMBOL_GPL(device_remove_bin_file);
/**
* device_schedule_callback - helper to schedule a callback for a device
* device_schedule_callback_owner - helper to schedule a callback for a device
* @dev: device.
* @func: callback function to invoke later.
* @owner: module owning the callback routine
*
* Attribute methods must not unregister themselves or their parent device
* (which would amount to the same thing). Attempts to do so will deadlock,
@ -493,20 +494,23 @@ EXPORT_SYMBOL_GPL(device_remove_bin_file);
* argument in the workqueue's process context. @dev will be pinned until
* @func returns.
*
* This routine is usually called via the inline device_schedule_callback(),
* which automatically sets @owner to THIS_MODULE.
*
* 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.
*
* NOTE: This routine won't work if CONFIG_SYSFS isn't set! It uses an
* underlying sysfs routine (since it is intended for use by attribute
* methods), and if sysfs isn't available you'll get nothing but -ENOSYS.
*/
int device_schedule_callback(struct device *dev,
void (*func)(struct device *))
int device_schedule_callback_owner(struct device *dev,
void (*func)(struct device *), struct module *owner)
{
return sysfs_schedule_callback(&dev->kobj,
(void (*)(void *)) func, dev);
(void (*)(void *)) func, dev, owner);
}
EXPORT_SYMBOL_GPL(device_schedule_callback);
EXPORT_SYMBOL_GPL(device_schedule_callback_owner);
static void klist_children_get(struct klist_node *n)
{

View file

@ -633,6 +633,7 @@ struct sysfs_schedule_callback_struct {
struct kobject *kobj;
void (*func)(void *);
void *data;
struct module *owner;
struct work_struct work;
};
@ -643,6 +644,7 @@ static void sysfs_schedule_callback_work(struct work_struct *work)
(ss->func)(ss->data);
kobject_put(ss->kobj);
module_put(ss->owner);
kfree(ss);
}
@ -651,6 +653,7 @@ static void sysfs_schedule_callback_work(struct work_struct *work)
* @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 @@ static void sysfs_schedule_callback_work(struct work_struct *work)
* 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;

View file

@ -367,8 +367,12 @@ extern int __must_check device_create_bin_file(struct device *dev,
struct bin_attribute *attr);
extern void device_remove_bin_file(struct device *dev,
struct bin_attribute *attr);
extern int device_schedule_callback(struct device *dev,
void (*func)(struct device *));
extern int device_schedule_callback_owner(struct device *dev,
void (*func)(struct device *), struct module *owner);
/* This is a macro to avoid include problems with THIS_MODULE */
#define device_schedule_callback(dev, func) \
device_schedule_callback_owner(dev, func, THIS_MODULE)
/* device resource management */
typedef void (*dr_release_t)(struct device *dev, void *res);

View file

@ -80,7 +80,7 @@ struct sysfs_ops {
#ifdef CONFIG_SYSFS
extern int sysfs_schedule_callback(struct kobject *kobj,
void (*func)(void *), void *data);
void (*func)(void *), void *data, struct module *owner);
extern int __must_check
sysfs_create_dir(struct kobject *, struct dentry *);
@ -137,7 +137,7 @@ extern int __must_check sysfs_init(void);
#else /* CONFIG_SYSFS */
static inline int sysfs_schedule_callback(struct kobject *kobj,
void (*func)(void *), void *data)
void (*func)(void *), void *data, struct module *owner)
{
return -ENOSYS;
}