6274 MAC tries to use aggr rings from downed links
Reviewed by: Bryan Cantrill <bryan@joyent.com>
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

*** 19,29 ****
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2014, Joyent, Inc.  All rights reserved.
   */
  
  /*
   * MAC Services Module
   *
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2015 Joyent, Inc.
   */
  
  /*
   * MAC Services Module
   *
*** 1675,1684 ****
--- 1675,1715 ----
  
          MAC_TX(mip, rh, mp, mcip);
          return (mp);
  }
  
+ /*
+  * Private function that is only used by aggr to update the default transmission
+  * ring. Because aggr exposes a pseudo Tx ring even for ports that may
+  * temporarily be down, it may need to update the default ring that is used by
+  * MAC such that it refers to a link that can actively be used to send traffic.
+  * Note that this is different from the case where the port has been removed
+  * from the group. In those cases, all of the rings will be torn down because
+  * the ring will no longer exist. It's important to give aggr a case where the
+  * rings can still exist such that it may be able to continue to send LACP PDUs
+  * to potentially restore the link.
+  *
+  * Finally, we explicitly don't do anything if the ring hasn't been enabled yet.
+  * This is to help out aggr which doesn't really know the internal state that
+  * MAC does about the rings and can't know that it's not quite ready for use
+  * yet.
+  */
+ void
+ mac_hwring_set_default(mac_handle_t mh, mac_ring_handle_t rh)
+ {
+         mac_impl_t *mip = (mac_impl_t *)mh;
+         mac_ring_t *ring = (mac_ring_t *)rh;
+ 
+         ASSERT(MAC_PERIM_HELD(mh));
+         VERIFY(mip->mi_state_flags & MIS_IS_AGGR);
+ 
+         if (ring->mr_state != MR_INUSE)
+                 return;
+ 
+         mip->mi_default_tx_ring = rh;
+ }
+ 
  int
  mac_hwgroup_addmac(mac_group_handle_t gh, const uint8_t *addr)
  {
          mac_group_t *group = (mac_group_t *)gh;