Commit 523ded71 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

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: default avatarAlan 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent fa1a8c23

drivers/base/core.c

+10 −6
Original line number Diff line number Diff line
@@ -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)

{

fs/sysfs/file.c

+11 −3
Original line number Diff line number Diff line
@@ -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;

include/linux/device.h

+6 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/sysfs.h

+2 −2
Original line number Diff line number Diff line
@@ -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;

}

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