10543 dls_unbind() needs better checking
Reviewed by: Andy Fiddaman <andy@omniosce.org>
Reviewed by: Dan McDonald <danmcd@joyent.com>

*** 23,33 ****
   * Use is subject to license terms.
   * Copyright 2012, Nexenta Systems, Inc. All rights reserved.
   */
  
  /*
!  * Copyright (c) 2013 Joyent, Inc.  All rights reserved.
   */
  
  /*
   * Data-Link Services Module
   */
--- 23,33 ----
   * Use is subject to license terms.
   * Copyright 2012, Nexenta Systems, Inc. All rights reserved.
   */
  
  /*
!  * Copyright (c) 2019 Joyent, Inc.  All rights reserved.
   */
  
  /*
   * Data-Link Services Module
   */
*** 216,232 ****
  
          if (dsp->ds_nonip && --dsp->ds_dlp->dl_nonip_cnt == 0)
                  mac_rx_bypass_enable(dsp->ds_mch);
  
          /*
!          * For VLAN SAP, there was a promisc handle registered when dls_bind.
!          * When unbind this dls link, we need to remove the promisc handle.
!          * See comments in dls_bind().
           */
          if (dsp->ds_vlan_mph != NULL) {
                  mac_promisc_remove(dsp->ds_vlan_mph);
                  dsp->ds_vlan_mph = NULL;
                  return;
          }
  
          /*
           * Unbind the dld_str_t by removing it from the hash table in the
--- 216,234 ----
  
          if (dsp->ds_nonip && --dsp->ds_dlp->dl_nonip_cnt == 0)
                  mac_rx_bypass_enable(dsp->ds_mch);
  
          /*
!          * A VLAN SAP does not actually add itself to the STREAM head today.
!          * While we initially set up a VLAN handle below, it's possible that
!          * something else will have come in and clobberd it.
           */
+         if (dsp->ds_sap == ETHERTYPE_VLAN) {
                  if (dsp->ds_vlan_mph != NULL) {
                          mac_promisc_remove(dsp->ds_vlan_mph);
                          dsp->ds_vlan_mph = NULL;
+                 }
                  return;
          }
  
          /*
           * Unbind the dld_str_t by removing it from the hash table in the