pbchk
cleanup port_free_event_local() semantics

*** 23,33 ****
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
  /*
!  * Copyright (c) 2014, Joyent, Inc.  All rights reserved.
   */
  
  #include <sys/types.h>
  #include <sys/vnode.h>
  #include <sys/vfs_opreg.h>
--- 23,33 ----
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
  /*
!  * Copyright 2020 Joyent, Inc.
   */
  
  #include <sys/types.h>
  #include <sys/vnode.h>
  #include <sys/vfs_opreg.h>
*** 113,131 ****
          port_kevent_t   *pkevp;
          int             events;         /* ignore events */
  
          mutex_enter(&portq->portq_mutex);
          while (pkevp = list_head(&portq->portq_list)) {
                  portq->portq_nent--;
                  list_remove(&portq->portq_list, pkevp);
                  if (pkevp->portkev_callback) {
                          (void) (*pkevp->portkev_callback)(pkevp->portkev_arg,
                              &events, pkevp->portkev_pid, PORT_CALLBACK_CLOSE,
                              pkevp);
                  }
!                 mutex_exit(&portq->portq_mutex);
!                 port_free_event_local(pkevp, 0);
                  mutex_enter(&portq->portq_mutex);
          }
  
          /*
           * Wait for any thread in pollwakeup(), accessing this port to
--- 113,141 ----
          port_kevent_t   *pkevp;
          int             events;         /* ignore events */
  
          mutex_enter(&portq->portq_mutex);
          while (pkevp = list_head(&portq->portq_list)) {
+                 port_t *pp = pkevp->portkev_port;
+ 
                  portq->portq_nent--;
                  list_remove(&portq->portq_list, pkevp);
                  if (pkevp->portkev_callback) {
                          (void) (*pkevp->portkev_callback)(pkevp->portkev_arg,
                              &events, pkevp->portkev_pid, PORT_CALLBACK_CLOSE,
                              pkevp);
                  }
!                 /*
!                  * Don't drop the portq_mutex, but instead perform the
!                  * decrement of port_curr in advance of calling
!                  * port_free_event_local().  We do need to reacquire
!                  * portq_mutex so we can properly wait for any
!                  * pollwakeup()-signalled threads to finish up.
!                  */
!                 if (--pp->port_curr < pp->port_max_events)
!                         cv_signal(&pp->port_cv);
!                 port_free_event_local(pkevp, B_FALSE);
                  mutex_enter(&portq->portq_mutex);
          }
  
          /*
           * Wait for any thread in pollwakeup(), accessing this port to