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>

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  /*
   * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
+  * Copyright 2017 Joyent, Inc.
   */
  
  
  /*
   * dcam.c
*** 1038,1109 ****
  
          return (rc);
  }
  
  
- /*
-  * dcam_chpoll
-  */
  /* ARGSUSED */
  int
  dcam_chpoll(dev_t dev, short events, int anyyet, short *reventsp,
      struct pollhead **phpp)
  {
          dcam_state_t    *softc_p;
!         int              instance, ring_buff_has_data, read_ptr_id;
!         size_t           read_ptr_pos, write_ptr_pos;
!         short            revent;
  
!         instance = DEV_TO_INSTANCE(dev);
  
          softc_p = (dcam_state_t *)ddi_get_soft_state(dcam_state_p, instance);
          if (softc_p == NULL) {
                  return (ENXIO);
          }
  
!         read_ptr_id     = 0;
!         revent          = 0;
  
-         if (softc_p->ring_buff_p == NULL) {
-                 ring_buff_has_data = 0;
-         } else {
                  mutex_enter(&softc_p->dcam_frame_is_done_mutex);
- 
                  read_ptr_pos =
!                     ring_buff_read_ptr_pos_get(softc_p->ring_buff_p,
!                     read_ptr_id);
! 
                  write_ptr_pos =
                      ring_buff_write_ptr_pos_get(softc_p->ring_buff_p);
- 
-                 if (read_ptr_pos != write_ptr_pos) {
-                         ring_buff_has_data = 1;
-                 } else {
-                         ring_buff_has_data = 0;
-                 }
- 
                  mutex_exit(&softc_p->dcam_frame_is_done_mutex);
-         }
  
!         /*
!          * now check for events
!          */
!         if ((events & POLLRDNORM) && ring_buff_has_data) {
                  revent |= POLLRDNORM;
          }
  
          if ((events & POLLPRI) && softc_p->param_status) {
                  revent |= POLLPRI;
          }
  
!         /* if no events have occurred */
!         if (revent == 0) {
!                 if (!anyyet) {
!                         *phpp = &softc_p->dcam_pollhead;
!                 }
!         }
! 
          *reventsp = revent;
  
          return (0);
  }
  
--- 1039,1096 ----
  
          return (rc);
  }
  
  
  /* ARGSUSED */
  int
  dcam_chpoll(dev_t dev, short events, int anyyet, short *reventsp,
      struct pollhead **phpp)
  {
          dcam_state_t    *softc_p;
!         int             instance;
!         short           revent = 0;
  
!         /*
!          * Without the logic to perform wakeups (see comment below), reject
!          * attempts at edge-triggered polling.
!          */
!         if (events & POLLET) {
!                 return (EPERM);
!         }
  
+         instance = DEV_TO_INSTANCE(dev);
          softc_p = (dcam_state_t *)ddi_get_soft_state(dcam_state_p, instance);
          if (softc_p == NULL) {
                  return (ENXIO);
          }
  
!         if (softc_p->ring_buff_p != NULL) {
!                 size_t read_ptr_pos, write_ptr_pos;
  
                  mutex_enter(&softc_p->dcam_frame_is_done_mutex);
                  read_ptr_pos =
!                     ring_buff_read_ptr_pos_get(softc_p->ring_buff_p, 0);
                  write_ptr_pos =
                      ring_buff_write_ptr_pos_get(softc_p->ring_buff_p);
                  mutex_exit(&softc_p->dcam_frame_is_done_mutex);
  
!                 if ((events & POLLRDNORM) && read_ptr_pos != write_ptr_pos) {
                          revent |= POLLRDNORM;
                  }
+         }
  
          if ((events & POLLPRI) && softc_p->param_status) {
                  revent |= POLLPRI;
          }
  
!         /*
!          * No portion of this driver was ever wired up to perform a
!          * pollwakeup() on an associated pollhead.  The lack of an emitted
!          * pollhead informs poll/devpoll that the event status of this resource
!          * is not cacheable.
!          */
          *reventsp = revent;
  
          return (0);
  }