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>

1 files changed, 10 insertions, 6 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index f69305c7269d..8aa090da1cd7 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -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)
 {