mcb: Acquire reference to carrier module in core

Acquire a reference to the carrier's kernel module in bus code, so
it can't be removed from the kernel while it still has a bus and thus
possibly devices attached to it.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reported-by: Andreas Werner <andreas.werner@men.de>
Tested-by: Andreas Werner <andreas.werner@men.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/mcb/mcb-core.c b/drivers/mcb/mcb-core.c
index f5923c253f7e..6f2c8522e14a 100644
--- a/drivers/mcb/mcb-core.c
+++ b/drivers/mcb/mcb-core.c
@@ -61,22 +61,36 @@ static int mcb_probe(struct device *dev)
         struct mcb_driver *mdrv = to_mcb_driver(dev->driver);
         struct mcb_device *mdev = to_mcb_device(dev);
         const struct mcb_device_id *found_id;
+        struct module *carrier_mod;
+        int ret;
 
         found_id = mcb_match_id(mdrv->id_table, mdev);
         if (!found_id)
                 return -ENODEV;
 
+        carrier_mod = mdev->dev.parent->driver->owner;
+        if (!try_module_get(carrier_mod))
+                return -EINVAL;
+
         get_device(dev);
-        return mdrv->probe(mdev, found_id);
+        ret = mdrv->probe(mdev, found_id);
+        if (ret)
+                module_put(carrier_mod);
+
+        return ret;
 }
 
 static int mcb_remove(struct device *dev)
 {
         struct mcb_driver *mdrv = to_mcb_driver(dev->driver);
         struct mcb_device *mdev = to_mcb_device(dev);
+        struct module *carrier_mod;
 
         mdrv->remove(mdev);
 
+        carrier_mod = mdev->dev.parent->driver->owner;
+        module_put(carrier_mod);
+
         put_device(&mdev->dev);
 
         return 0;