bonding: adjust locking comments

Now that locks have been removed, remove some unnecessary comments and
adjust others to reflect reality. Also add a comment to "mode_lock" to
describe its current users and give a brief summary why they need it.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 0cda34b..3aff1a8 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -195,6 +195,12 @@
 	s32      slave_cnt; /* never change this value outside the attach/detach wrappers */
 	int     (*recv_probe)(const struct sk_buff *, struct bonding *,
 			      struct slave *);
+	/* mode_lock is used for mode-specific locking needs, currently used by:
+	 * 3ad mode (4) - protect against running bond_3ad_unbind_slave() and
+	 *                bond_3ad_state_machine_handler() concurrently.
+	 * TLB mode (5) - to sync the use and modifications of its hash table
+	 * ALB mode (6) - to sync the use and modifications of its hash table
+	 */
 	spinlock_t mode_lock;
 	u8	 send_peer_notif;
 	u8       igmp_retrans;