atm: add owner of push() callback to atmvcc

The atm is using atmvcc->push(vcc, NULL) callback to notify protocol
that vcc will be closed and protocol must detach from it. This callback
is usually used by protocol to decrement module usage count by module_put(),
but it leaves small window then module is still used after module_put().

Now the owner of push() callback is kept in atmvcc and
module_put(atmvcc->owner) is called after the protocol is detached from vcc.

Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Chas Williams <chas@cmf.nrl.navy.mil>
diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
index 22ef21c..72db2af 100644
--- a/include/linux/atmdev.h
+++ b/include/linux/atmdev.h
@@ -106,6 +106,7 @@
 	void		*dev_data;	/* per-device data */
 	void		*proto_data;	/* per-protocol data */
 	struct k_atm_aal_stats *stats;	/* pointer to AAL stats group */
+	struct module *owner;		/* owner of ->push function */
 	/* SVC part --- may move later ------------------------------------- */
 	short		itf;		/* interface number */
 	struct sockaddr_atmsvc local;