driver core: refcounting fix

Fix a reference counting bug exposed by commit
725522b5453dd680412f2b6463a988e4fd148757.  If driver.mod_name exists, we
take a reference in module_add_driver(), and never release it.  Undo that
reference in module_remove_driver().

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 8c25b1a04fa6..1ecf08106381 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2425,6 +2425,12 @@ void module_remove_driver(struct device_driver *drv)
                         kfree(driver_name);
                 }
         }
+        /*
+         * Undo the additional reference we added in module_add_driver()
+         * via kset_find_obj()
+         */
+        if (drv->mod_name)
+                kobject_put(&drv->kobj);
 }
 EXPORT_SYMBOL(module_remove_driver);
 #endif