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>

*** 38,47 ****
--- 38,48 ----
   * "Header: bpf.c,v 1.67 96/09/26 22:00:52 leres Exp ";
   */
  /*
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
+  * Copyright 2017 Joyent, Inc.
   */
  
  /*
   * The BPF implements the following access controls for zones attempting
   * to read and write data. Writing of data requires that the net_rawaccess
*** 1394,1417 ****
          mutex_exit(&d->bd_lock);
  
          return (0);
  }
  
! /*
!  * Support for poll() system call
!  *
!  * Return true iff the specific operation will not block indefinitely - with
!  * the assumption that it is safe to positively acknowledge a request for the
!  * ability to write to the BPF device.
!  * Otherwise, return false but make a note that a selnotify() must be done.
!  */
  int
  bpfchpoll(dev_t dev, short events, int anyyet, short *reventsp,
      struct pollhead **phpp)
  {
          struct bpf_d *d = bpf_dev_get(getminor(dev));
  
          if (events & (POLLIN | POLLRDNORM)) {
                  /*
                   * An imitation of the FIONREAD ioctl code.
                   */
                  mutex_enter(&d->bd_lock);
--- 1395,1419 ----
          mutex_exit(&d->bd_lock);
  
          return (0);
  }
  
! /* ARGSUSED */
  int
  bpfchpoll(dev_t dev, short events, int anyyet, short *reventsp,
      struct pollhead **phpp)
  {
          struct bpf_d *d = bpf_dev_get(getminor(dev));
  
+         /*
+          * Until this driver is modified to issue proper pollwakeup() calls on
+          * its pollhead, edge-triggered polling is not allowed.
+          */
+         if (events & POLLET) {
+                 return (EPERM);
+         }
+ 
          if (events & (POLLIN | POLLRDNORM)) {
                  /*
                   * An imitation of the FIONREAD ioctl code.
                   */
                  mutex_enter(&d->bd_lock);
*** 1418,1430 ****
                  if (d->bd_hlen != 0 ||
                      ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) &&
                      d->bd_slen != 0)) {
                          *reventsp |= events & (POLLIN | POLLRDNORM);
                  } else {
                          *reventsp = 0;
-                         if (!anyyet)
-                                 *phpp = &d->bd_poll;
                          /* Start the read timeout if necessary */
                          if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
                                  bpf_clear_timeout(d);
                                  /*
                                   * Only allow the timeout to be set once.
--- 1420,1436 ----
                  if (d->bd_hlen != 0 ||
                      ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) &&
                      d->bd_slen != 0)) {
                          *reventsp |= events & (POLLIN | POLLRDNORM);
                  } else {
+                         /*
+                          * Until the bpf driver has been updated to include
+                          * adequate pollwakeup() logic, no pollhead will be
+                          * emitted here, preventing the resource from being
+                          * cached by poll()/devpoll/epoll.
+                          */
                          *reventsp = 0;
                          /* Start the read timeout if necessary */
                          if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
                                  bpf_clear_timeout(d);
                                  /*
                                   * Only allow the timeout to be set once.