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>

@@ -20,10 +20,11 @@
  */
 
 /*
  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright 2017 Joyent, Inc.
  */
 
 
 /*
  * srn  Provide apm-like interfaces to Xorg

@@ -261,14 +262,15 @@
         clone = SRN_MINOR_TO_CLONE(getminor(dev));
         if ((events & (POLLIN | POLLRDNORM)) && srn_poll_cnt[clone]) {
                 *reventsp |= (POLLIN | POLLRDNORM);
         } else {
                 *reventsp = 0;
-                if (!anyyet) {
+        }
+
+        if ((*reventsp == 0 && !anyyet) || (events & POLLET)) {
                         *phpp = &srn_pollhead[clone];
                 }
-        }
         return (0);
 }
 
 /*ARGSUSED*/
 static int