8634 epoll fails to wake on certain edge-triggered conditions
8635 epoll should not emit POLLNVAL
8636 recursive epoll should emit EPOLLRDNORM
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: Igor Kozhukhov <igor@dilos.org>

*** 23,33 ****
   * Use is subject to license terms.
   * Copyright (c) 2016 by Delphix. All rights reserved.
   */
  
  /*
!  * Copyright (c) 2015, Joyent, Inc.  All rights reserved.
   * Copyright 2017 James S Blachly, MD <james.blachly@gmail.com>
   */
  
  /*
   * Memory special file
--- 23,33 ----
   * Use is subject to license terms.
   * Copyright (c) 2016 by Delphix. All rights reserved.
   */
  
  /*
!  * Copyright 2017 Joyent, Inc.
   * Copyright 2017 James S Blachly, MD <james.blachly@gmail.com>
   */
  
  /*
   * Memory special file
*** 257,270 ****
          case M_ALLKMEM:
                  *reventsp = events & (POLLIN | POLLOUT | POLLPRI | POLLRDNORM |
                      POLLWRNORM | POLLRDBAND | POLLWRBAND);
                  /*
                   * A non NULL pollhead pointer should be returned in case
!                  * user polls for 0 events.
                   */
!                 *phpp = !anyyet && !*reventsp ?
!                     &mm_pollhd : (struct pollhead *)NULL;
                  return (0);
          default:
                  /* no other devices currently support polling */
                  return (ENXIO);
          }
--- 257,271 ----
          case M_ALLKMEM:
                  *reventsp = events & (POLLIN | POLLOUT | POLLPRI | POLLRDNORM |
                      POLLWRNORM | POLLRDBAND | POLLWRBAND);
                  /*
                   * A non NULL pollhead pointer should be returned in case
!                  * user polls for 0 events or is doing an edge-triggerd poll.
                   */
!                 if ((!*reventsp && !anyyet) || (events & POLLET)) {
!                         *phpp = &mm_pollhd;
!                 }
                  return (0);
          default:
                  /* no other devices currently support polling */
                  return (ENXIO);
          }