5133 Upstream SMB client fixes: Nexenta SUP-538 and SUP-548

*** 180,196 ****
  
          /*
           * If we have an IOD, it should immediately notice
           * that its connection has closed.  But in case
           * it doesn't, let's also send it a signal.
-          * (but don't shoot our own foot!)
-          * Note: the iod calls smb_iod_invrq on its way out.
           */
          if (vcp->iod_thr != NULL &&
              vcp->iod_thr != curthread) {
                  tsignal(vcp->iod_thr, SIGKILL);
          }
  }
  
  /*
   * Send one request.
   *
--- 180,196 ----
  
          /*
           * If we have an IOD, it should immediately notice
           * that its connection has closed.  But in case
           * it doesn't, let's also send it a signal.
           */
+         SMB_VC_LOCK(vcp);
          if (vcp->iod_thr != NULL &&
              vcp->iod_thr != curthread) {
                  tsignal(vcp->iod_thr, SIGKILL);
          }
+         SMB_VC_UNLOCK(vcp);
  }
  
  /*
   * Send one request.
   *