13902 Fix for 13717 may break 8-disk raidz2
13915 installctx() blocking allocate causes problems
Portions contributed by: Jerry Jelinek <gjelinek@gmail.com>
Change-Id: I934d69946cec42630fc541fa8c7385b862b69ca2

*** 19,29 ****
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2018 Joyent, Inc.
   * Copyright 2020 Oxide Computer Company
   */
  
  /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  /*        All Rights Reserved   */
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2021 Joyent, Inc.
   * Copyright 2020 Oxide Computer Company
   */
  
  /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  /*        All Rights Reserved   */
*** 716,727 ****
  extern  void    thread_exit(void) __NORETURN;
  extern  void    thread_free(kthread_t *);
  extern  void    thread_rele(kthread_t *);
  extern  void    thread_join(kt_did_t);
  extern  int     reaper(void);
  extern  void    installctx(kthread_t *, void *, void (*)(), void (*)(),
!     void (*)(), void (*)(), void (*)(), void (*)());
  extern  int     removectx(kthread_t *, void *, void (*)(), void (*)(),
      void (*)(), void (*)(), void (*)(), void (*)());
  extern  void    savectx(kthread_t *);
  extern  void    restorectx(kthread_t *);
  extern  void    forkctx(kthread_t *, kthread_t *);
--- 716,728 ----
  extern  void    thread_exit(void) __NORETURN;
  extern  void    thread_free(kthread_t *);
  extern  void    thread_rele(kthread_t *);
  extern  void    thread_join(kt_did_t);
  extern  int     reaper(void);
+ extern  struct ctxop *installctx_preallocate(void);
  extern  void    installctx(kthread_t *, void *, void (*)(), void (*)(),
!     void (*)(), void (*)(), void (*)(), void (*)(), struct ctxop *);
  extern  int     removectx(kthread_t *, void *, void (*)(), void (*)(),
      void (*)(), void (*)(), void (*)(), void (*)());
  extern  void    savectx(kthread_t *);
  extern  void    restorectx(kthread_t *);
  extern  void    forkctx(kthread_t *, kthread_t *);