12976 system panics with error in IP module
Reviewed by: Andy Fiddaman <andy@omniosce.org>
Reviewed by: Paul Winder <p.winder@me.com>

*** 19,32 ****
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
-  * Copyright 2019 Joyent, Inc.
   * Copyright (c) 2011 Nexenta Systems, Inc. All rights reserved.
   * Copyright (c) 2013, 2017 by Delphix. All rights reserved.
   * Copyright 2014, OmniTI Computer Consulting, Inc. All rights reserved.
   */
  /* Copyright (c) 1990 Mentat Inc. */
  
  #include <sys/types.h>
  #include <sys/stream.h>
--- 19,32 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2011 Nexenta Systems, Inc. All rights reserved.
   * Copyright (c) 2013, 2017 by Delphix. All rights reserved.
   * Copyright 2014, OmniTI Computer Consulting, Inc. All rights reserved.
+  * Copyright 2020 Joyent, Inc.
   */
  /* Copyright (c) 1990 Mentat Inc. */
  
  #include <sys/types.h>
  #include <sys/stream.h>
*** 1017,1030 ****
          cv_signal(&tcp->tcp_closecv);
          mutex_exit(&tcp->tcp_closelock);
  
          /* If we have an upper handle (socket), release it */
          if (IPCL_IS_NONSTR(connp)) {
!                 ASSERT(connp->conn_upper_handle != NULL);
!                 (*connp->conn_upcalls->su_closed)(connp->conn_upper_handle);
                  connp->conn_upper_handle = NULL;
                  connp->conn_upcalls = NULL;
          }
  }
  
  void
  tcp_close_common(conn_t *connp, int flags)
--- 1017,1043 ----
          cv_signal(&tcp->tcp_closecv);
          mutex_exit(&tcp->tcp_closelock);
  
          /* If we have an upper handle (socket), release it */
          if (IPCL_IS_NONSTR(connp)) {
!                 sock_upcalls_t *upcalls = connp->conn_upcalls;
!                 sock_upper_handle_t handle = connp->conn_upper_handle;
! 
!                 ASSERT(upcalls != NULL);
!                 ASSERT(upcalls->su_closed != NULL);
!                 ASSERT(handle != NULL);
!                 /*
!                  * Set these to NULL first because closed() will free upper
!                  * structures.  Acquire conn_lock because an external caller
!                  * like conn_get_socket_info() will upcall if these are
!                  * non-NULL.
!                  */
!                 mutex_enter(&connp->conn_lock);
                  connp->conn_upper_handle = NULL;
                  connp->conn_upcalls = NULL;
+                 mutex_exit(&connp->conn_lock);
+                 upcalls->su_closed(handle);
          }
  }
  
  void
  tcp_close_common(conn_t *connp, int flags)
*** 1419,1435 ****
           * handle, release it. As a result of fallback we might also see
           * STREAMS based conns with upper handles, in which case there is
           * nothing to do other than clearing the field.
           */
          if (connp->conn_upper_handle != NULL) {
                  if (IPCL_IS_NONSTR(connp)) {
!                         (*connp->conn_upcalls->su_closed)(
!                             connp->conn_upper_handle);
                          tcp->tcp_detached = B_TRUE;
                  }
-                 connp->conn_upper_handle = NULL;
-                 connp->conn_upcalls = NULL;
          }
  }
  
  /*
   * tcp_get_conn/tcp_free_conn
--- 1432,1461 ----
           * handle, release it. As a result of fallback we might also see
           * STREAMS based conns with upper handles, in which case there is
           * nothing to do other than clearing the field.
           */
          if (connp->conn_upper_handle != NULL) {
+                 sock_upcalls_t *upcalls = connp->conn_upcalls;
+                 sock_upper_handle_t handle = connp->conn_upper_handle;
+ 
+                 /*
+                  * Set these to NULL first because closed() will free upper
+                  * structures.  Acquire conn_lock because an external caller
+                  * like conn_get_socket_info() will upcall if these are
+                  * non-NULL.
+                  */
+                 mutex_enter(&connp->conn_lock);
+                 connp->conn_upper_handle = NULL;
+                 connp->conn_upcalls = NULL;
+                 mutex_exit(&connp->conn_lock);
                  if (IPCL_IS_NONSTR(connp)) {
!                         ASSERT(upcalls != NULL);
!                         ASSERT(upcalls->su_closed != NULL);
!                         ASSERT(handle != NULL);
!                         upcalls->su_closed(handle);
                          tcp->tcp_detached = B_TRUE;
                  }
          }
  }
  
  /*
   * tcp_get_conn/tcp_free_conn