HACK epoll TEST_PANIC_FALLBACK
[metze/samba/wip.git] / lib / tevent / tevent_epoll.c
index 61a8525d2bcfb11216890a063c94f8a7cc9e415a..a909dc98a0532c8ab3c9cf7dd263b1cb3f910c2d 100644 (file)
@@ -4,7 +4,8 @@
    main select loop and event handling - epoll implementation
 
    Copyright (C) Andrew Tridgell       2003-2005
-   Copyright (C) Stefan Metzmacher     2005-2009
+   Copyright (C) Stefan Metzmacher     2005-2013
+   Copyright (C) Jeremy Allison                2013
 
      ** NOTE! The following LGPL license applies to the tevent
      ** library. This does NOT imply that all of Samba is released
@@ -31,6 +32,8 @@
 #include "tevent_internal.h"
 #include "tevent_util.h"
 
+#define TEST_PANIC_FALLBACK
+
 struct epoll_event_context {
        /* a pointer back to the generic event_context */
        struct tevent_context *ev;
@@ -40,15 +43,61 @@ struct epoll_event_context {
 
        pid_t pid;
 
+       bool panic_force_replay;
+       bool *panic_state;
        bool (*panic_fallback)(struct tevent_context *ev, bool replay);
 };
 
+#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT     (1<<0)
+#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR  (1<<1)
+#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR     (1<<2)
+#define EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX       (1<<3)
+
 #ifdef TEST_PANIC_FALLBACK
-static int epoll_wait_panic_fallback(int epfd,
-                               struct epoll_event *events,
-                               int maxevents,
-                               int timeout)
+
+static int epoll_create_panic_fallback(struct epoll_event_context *epoll_ev,
+                                      int size)
+{
+       if (epoll_ev->panic_fallback == NULL) {
+               return epoll_create(size);
+       }
+
+       /* 50% of the time, fail... */
+       if ((random() % 2) == 0) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       return epoll_create(size);
+}
+
+static int epoll_ctl_panic_fallback(struct epoll_event_context *epoll_ev,
+                                   int epfd, int op, int fd,
+                                   struct epoll_event *event)
 {
+       if (epoll_ev->panic_fallback == NULL) {
+               return epoll_ctl(epfd, op, fd, event);
+       }
+
+       /* 50% of the time, fail... */
+       if ((random() % 2) == 0) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       return epoll_ctl(epfd, op, fd, event);
+}
+
+static int epoll_wait_panic_fallback(struct epoll_event_context *epoll_ev,
+                                    int epfd,
+                                    struct epoll_event *events,
+                                    int maxevents,
+                                    int timeout)
+{
+       if (epoll_ev->panic_fallback == NULL) {
+               return epoll_wait(epfd, events, maxevents, timeout);
+       }
+
        /* 50% of the time, fail... */
        if ((random() % 2) == 0) {
                errno = EINVAL;
@@ -58,7 +107,12 @@ static int epoll_wait_panic_fallback(int epfd,
        return epoll_wait(epfd, events, maxevents, timeout);
 }
 
-#define epoll_wait epoll_wait_panic_fallback
+#define epoll_create(_size) \
+       epoll_create_panic_fallback(epoll_ev, _size)
+#define epoll_ctl(_epfd, _op, _fd, _event) \
+       epoll_ctl_panic_fallback(epoll_ev,_epfd, _op, _fd, _event)
+#define epoll_wait(_epfd, _events, _maxevents, _timeout) \
+       epoll_wait_panic_fallback(epoll_ev, _epfd, _events, _maxevents, _timeout)
 #endif
 
 /*
@@ -90,19 +144,32 @@ static void epoll_panic(struct epoll_event_context *epoll_ev,
                        const char *reason, bool replay)
 {
        struct tevent_context *ev = epoll_ev->ev;
+       bool (*panic_fallback)(struct tevent_context *ev, bool replay);
 
-       if (epoll_ev->panic_fallback == NULL) {
+       panic_fallback = epoll_ev->panic_fallback;
+
+       if (epoll_ev->panic_state != NULL) {
+               *epoll_ev->panic_state = true;
+       }
+
+       if (epoll_ev->panic_force_replay) {
+               replay = true;
+       }
+
+       TALLOC_FREE(ev->additional_data);
+
+       if (panic_fallback == NULL) {
                tevent_debug(ev, TEVENT_DEBUG_FATAL,
                        "%s (%s) replay[%u] - calling abort()\n",
                        reason, strerror(errno), (unsigned)replay);
                abort();
        }
 
-       tevent_debug(ev, TEVENT_DEBUG_WARNING,
+       tevent_debug(ev, TEVENT_DEBUG_ERROR,
                     "%s (%s) replay[%u] - calling panic_fallback\n",
                     reason, strerror(errno), (unsigned)replay);
 
-       if (!epoll_ev->panic_fallback(ev, replay)) {
+       if (!panic_fallback(ev, replay)) {
                /* Fallback failed. */
                tevent_debug(ev, TEVENT_DEBUG_FATAL,
                        "%s (%s) replay[%u] - calling abort()\n",
@@ -155,7 +222,7 @@ static int epoll_init_ctx(struct epoll_event_context *epoll_ev)
        return 0;
 }
 
-static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde);
+static void epoll_update_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde);
 
 /*
   reopen the epoll handle when our pid changes
@@ -165,6 +232,8 @@ static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_
 static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
 {
        struct tevent_fd *fde;
+       bool *caller_panic_state = epoll_ev->panic_state;
+       bool panic_triggered = false;
 
        if (epoll_ev->pid == getpid()) {
                return;
@@ -173,8 +242,7 @@ static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
        close(epoll_ev->epoll_fd);
        epoll_ev->epoll_fd = epoll_create(64);
        if (epoll_ev->epoll_fd == -1) {
-               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
-                            "Failed to recreate epoll handle after fork\n");
+               epoll_panic(epoll_ev, "epoll_create() failed", false);
                return;
        }
 
@@ -184,14 +252,113 @@ static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
        }
 
        epoll_ev->pid = getpid();
+       epoll_ev->panic_state = &panic_triggered;
        for (fde=epoll_ev->ev->fd_events;fde;fde=fde->next) {
-               epoll_add_event(epoll_ev, fde);
+               fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+               epoll_update_event(epoll_ev, fde);
+
+               if (panic_triggered) {
+                       if (caller_panic_state != NULL) {
+                               *caller_panic_state = true;
+                       }
+                       return;
+               }
        }
+       epoll_ev->panic_state = NULL;
 }
 
-#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT     (1<<0)
-#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR  (1<<1)
-#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR     (1<<2)
+/*
+ epoll cannot add the same file descriptor twice, once
+ with read, once with write which is allowed by the
+ tevent backend. Multiplex the existing fde, flag it
+ as such so we can search for the correct fde on
+ event triggering.
+*/
+
+static int epoll_add_multiplex_fd(struct epoll_event_context *epoll_ev,
+                                 struct tevent_fd *add_fde)
+{
+       struct epoll_event event;
+       struct tevent_fd *mpx_fde;
+       int ret;
+
+       /* Find the existing fde that caused the EEXIST error. */
+       for (mpx_fde = epoll_ev->ev->fd_events; mpx_fde; mpx_fde = mpx_fde->next) {
+               if (mpx_fde->fd != add_fde->fd) {
+                       continue;
+               }
+
+               if (mpx_fde == add_fde) {
+                       continue;
+               }
+
+               break;
+       }
+       if (mpx_fde == NULL) {
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
+                            "can't find multiplex fde for fd[%d]",
+                            add_fde->fd);
+               return -1;
+       }
+
+       if (mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+               /* Logic error. Can't have more than 2 multiplexed fde's. */
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
+                            "multiplex fde for fd[%d] is already multiplexed\n",
+                            mpx_fde->fd);
+               return -1;
+       }
+
+       /*
+        * The multiplex fde must have the same fd, and also
+        * already have an epoll event attached.
+        */
+       if (!(mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) {
+               /* Logic error. Can't have more than 2 multiplexed fde's. */
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
+                            "multiplex fde for fd[%d] has no event\n",
+                            mpx_fde->fd);
+               return -1;
+       }
+
+       /* Modify the orig_fde to add in the new flags. */
+       ZERO_STRUCT(event);
+       event.events = epoll_map_flags(mpx_fde->flags);
+       event.events |= epoll_map_flags(add_fde->flags);
+       event.data.ptr = mpx_fde;
+       ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, mpx_fde->fd, &event);
+       if (ret != 0 && errno == EBADF) {
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
+                            "EPOLL_CTL_MOD EBADF for "
+                            "add_fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
+                            add_fde, mpx_fde, add_fde->fd);
+               DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
+               mpx_fde->event_ctx = NULL;
+               DLIST_REMOVE(epoll_ev->ev->fd_events, add_fde);
+               add_fde->event_ctx = NULL;
+               return 0;
+       } else if (ret != 0) {
+               return ret;
+       }
+
+       /*
+        * Make each fde->additional_data pointers point at each other
+        * so we can look them up from each other. They are now paired.
+        */
+       mpx_fde->additional_data = (struct tevent_fd *)add_fde;
+       add_fde->additional_data = (struct tevent_fd *)mpx_fde;
+
+       /* Now flag both fde's as being multiplexed. */
+       mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
+       add_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
+
+       /* we need to keep the GOT_ERROR flag */
+       if (mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR) {
+               add_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+       }
+
+       return 0;
+}
 
 /*
  add the epoll event to the given fd_event
@@ -199,27 +366,70 @@ static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
 static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 {
        struct epoll_event event;
+       int ret;
+       struct tevent_fd *mpx_fde = NULL;
 
-       if (epoll_ev->epoll_fd == -1) return;
-
+       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
        fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 
-       /* if we don't want events yet, don't add an epoll_event */
-       if (fde->flags == 0) return;
+       if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+               /*
+                * This is a multiplexed fde, we need to include both
+                * flags in the modified event.
+                */
+               mpx_fde = talloc_get_type_abort(fde->additional_data,
+                                               struct tevent_fd);
+
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
 
        ZERO_STRUCT(event);
        event.events = epoll_map_flags(fde->flags);
+       if (mpx_fde != NULL) {
+               event.events |= epoll_map_flags(mpx_fde->flags);
+       }
        event.data.ptr = fde;
-       if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) {
+       ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event);
+       if (ret != 0 && errno == EBADF) {
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
+                            "EPOLL_CTL_ADD EBADF for "
+                            "fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
+                            fde, mpx_fde, fde->fd);
+               DLIST_REMOVE(epoll_ev->ev->fd_events, fde);
+               fde->event_ctx = NULL;
+               if (mpx_fde != NULL) {
+                       DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
+                       mpx_fde->event_ctx = NULL;
+               }
+               return;
+       } else if (ret != 0 && errno == EEXIST && mpx_fde == NULL) {
+               ret = epoll_add_multiplex_fd(epoll_ev, fde);
+               if (ret != 0) {
+                       epoll_panic(epoll_ev, "epoll_add_multiplex_fd failed",
+                                   false);
+                       return;
+               }
+       } else if (ret != 0) {
                epoll_panic(epoll_ev, "EPOLL_CTL_ADD failed", false);
                return;
        }
-       fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 
+       fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
        /* only if we want to read we want to tell the event handler about errors */
        if (fde->flags & TEVENT_FD_READ) {
                fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
        }
+
+       if (mpx_fde == NULL) {
+               return;
+       }
+
+       mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+       /* only if we want to read we want to tell the event handler about errors */
+       if (mpx_fde->flags & TEVENT_FD_READ) {
+               mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
 }
 
 /*
@@ -228,23 +438,50 @@ static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_
 static void epoll_del_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 {
        struct epoll_event event;
+       int ret;
+       struct tevent_fd *mpx_fde = NULL;
 
-       if (epoll_ev->epoll_fd == -1) return;
-
+       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
        fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 
-       /* if there's no epoll_event, we don't need to delete it */
-       if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return;
+       if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+               /*
+                * This is a multiplexed fde, we need to modify both events.
+                */
+               mpx_fde = talloc_get_type_abort(fde->additional_data,
+                                               struct tevent_fd);
+
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
 
        ZERO_STRUCT(event);
-       event.events = epoll_map_flags(fde->flags);
-       event.data.ptr = fde;
-       if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event) != 0) {
-               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
-                            "epoll_del_event failed! probable early close bug (%s)\n",
-                            strerror(errno));
+       ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event);
+       if (ret != 0 && errno == ENOENT) {
+               /*
+                * This can happen after a epoll_check_reopen
+                * within epoll_event_fd_destructor.
+                */
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_TRACE,
+                            "EPOLL_CTL_DEL ignoring ENOENT for fd[%d]\n",
+                            fde->fd);
+               return;
+       } else if (ret != 0 && errno == EBADF) {
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_WARNING,
+                            "EPOLL_CTL_DEL EBADF for "
+                            "fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
+                            fde, mpx_fde, fde->fd);
+               DLIST_REMOVE(epoll_ev->ev->fd_events, fde);
+               fde->event_ctx = NULL;
+               if (mpx_fde != NULL) {
+                       DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
+                       mpx_fde->event_ctx = NULL;
+               }
+               return;
+       } else if (ret != 0) {
+               epoll_panic(epoll_ev, "EPOLL_CTL_DEL failed", false);
+               return;
        }
-       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 }
 
 /*
@@ -252,34 +489,88 @@ static void epoll_del_event(struct epoll_event_context *epoll_ev, struct tevent_
 */
 static void epoll_mod_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 {
+       struct tevent_fd *mpx_fde = NULL;
        struct epoll_event event;
-       if (epoll_ev->epoll_fd == -1) return;
+       int ret;
 
+       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
        fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
 
+       if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+               /*
+                * This is a multiplexed fde, we need to include both
+                * flags in the modified event.
+                */
+               mpx_fde = talloc_get_type_abort(fde->additional_data,
+                                               struct tevent_fd);
+
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
+
        ZERO_STRUCT(event);
        event.events = epoll_map_flags(fde->flags);
+       if (mpx_fde != NULL) {
+               event.events |= epoll_map_flags(mpx_fde->flags);
+       }
        event.data.ptr = fde;
-       if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) {
+       ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event);
+       if (ret != 0 && errno == EBADF) {
+               tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
+                            "EPOLL_CTL_MOD EBADF for "
+                            "fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
+                            fde, mpx_fde, fde->fd);
+               DLIST_REMOVE(epoll_ev->ev->fd_events, fde);
+               fde->event_ctx = NULL;
+               if (mpx_fde != NULL) {
+                       DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
+                       mpx_fde->event_ctx = NULL;
+               }
+               return;
+       } else if (ret != 0) {
                epoll_panic(epoll_ev, "EPOLL_CTL_MOD failed", false);
                return;
        }
 
+       fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
        /* only if we want to read we want to tell the event handler about errors */
        if (fde->flags & TEVENT_FD_READ) {
                fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
        }
+
+       if (mpx_fde == NULL) {
+               return;
+       }
+
+       mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+       /* only if we want to read we want to tell the event handler about errors */
+       if (mpx_fde->flags & TEVENT_FD_READ) {
+               mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
 }
 
-static void epoll_change_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
+static void epoll_update_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
 {
        bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
        bool want_read = (fde->flags & TEVENT_FD_READ);
        bool want_write= (fde->flags & TEVENT_FD_WRITE);
+       struct tevent_fd *mpx_fde = NULL;
+
+       if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+               /*
+                * work out what the multiplexed fde wants.
+                */
+               mpx_fde = talloc_get_type_abort(fde->additional_data,
+                                               struct tevent_fd);
 
-       if (epoll_ev->epoll_fd == -1) return;
+               if (mpx_fde->flags & TEVENT_FD_READ) {
+                       want_read = true;
+               }
 
-       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+               if (mpx_fde->flags & TEVENT_FD_WRITE) {
+                       want_write = true;
+               }
+       }
 
        /* there's already an event */
        if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
@@ -304,6 +595,38 @@ static void epoll_change_event(struct epoll_event_context *epoll_ev, struct teve
        }
 }
 
+/*
+  Cope with epoll returning EPOLLHUP|EPOLLERR on an event.
+  Return true if there's nothing else to do, false if
+  this event needs further handling.
+*/
+static bool epoll_handle_hup_or_err(struct epoll_event_context *epoll_ev,
+                               struct tevent_fd *fde)
+{
+       if (fde == NULL) {
+               /* Nothing to do if no event. */
+               return true;
+       }
+
+       fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+       /*
+        * if we only wait for TEVENT_FD_WRITE, we should not tell the
+        * event handler about it, and remove the epoll_event,
+        * as we only report errors when waiting for read events,
+        * to match the select() behavior
+        */
+       if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
+               /*
+                * Do the same as the poll backend and
+                * remove the writeable flag.
+                */
+               fde->flags &= ~TEVENT_FD_WRITE;
+               return true;
+       }
+       /* This has TEVENT_FD_READ set, we're not finished. */
+       return false;
+}
+
 /*
   event loop handling using epoll
 */
@@ -313,8 +636,7 @@ static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval
 #define MAXEVENTS 1
        struct epoll_event events[MAXEVENTS];
        int timeout = -1;
-
-       if (epoll_ev->epoll_fd == -1) return -1;
+       int wait_errno;
 
        if (tvalp) {
                /* it's better to trigger timed events a bit later than too early */
@@ -328,15 +650,16 @@ static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval
 
        tevent_trace_point_callback(epoll_ev->ev, TEVENT_TRACE_BEFORE_WAIT);
        ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout);
+       wait_errno = errno;
        tevent_trace_point_callback(epoll_ev->ev, TEVENT_TRACE_AFTER_WAIT);
 
-       if (ret == -1 && errno == EINTR && epoll_ev->ev->signal_events) {
+       if (ret == -1 && wait_errno == EINTR && epoll_ev->ev->signal_events) {
                if (tevent_common_check_signal(epoll_ev->ev)) {
                        return 0;
                }
        }
 
-       if (ret == -1 && errno != EINTR) {
+       if (ret == -1 && wait_errno != EINTR) {
                epoll_panic(epoll_ev, "epoll_wait() failed", true);
                return -1;
        }
@@ -351,27 +674,66 @@ static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval
                struct tevent_fd *fde = talloc_get_type(events[i].data.ptr, 
                                                       struct tevent_fd);
                uint16_t flags = 0;
+               struct tevent_fd *mpx_fde = NULL;
 
                if (fde == NULL) {
                        epoll_panic(epoll_ev, "epoll_wait() gave bad data", true);
                        return -1;
                }
-               if (events[i].events & (EPOLLHUP|EPOLLERR)) {
-                       fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+               if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
                        /*
-                        * if we only wait for TEVENT_FD_WRITE, we should not tell the
-                        * event handler about it, and remove the epoll_event,
-                        * as we only report errors when waiting for read events,
-                        * to match the select() behavior
+                        * Save off the multiplexed event in case we need
+                        * to use it to call the handler function.
                         */
-                       if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
-                               epoll_del_event(epoll_ev, fde);
+                       mpx_fde = talloc_get_type_abort(fde->additional_data,
+                                                       struct tevent_fd);
+               }
+               if (events[i].events & (EPOLLHUP|EPOLLERR)) {
+                       bool handled_fde = epoll_handle_hup_or_err(epoll_ev, fde);
+                       bool handled_mpx = epoll_handle_hup_or_err(epoll_ev, mpx_fde);
+
+                       if (handled_fde && handled_mpx) {
+                               epoll_update_event(epoll_ev, fde);
                                continue;
                        }
+
+                       if (!handled_mpx) {
+                               /*
+                                * If the mpx event was the one that needs
+                                * further handling, it's the TEVENT_FD_READ
+                                * event so switch over and call that handler.
+                                */
+                               fde = mpx_fde;
+                               mpx_fde = NULL;
+                       }
                        flags |= TEVENT_FD_READ;
                }
                if (events[i].events & EPOLLIN) flags |= TEVENT_FD_READ;
                if (events[i].events & EPOLLOUT) flags |= TEVENT_FD_WRITE;
+
+               if (flags & TEVENT_FD_WRITE) {
+                       if (fde->flags & TEVENT_FD_WRITE) {
+                               mpx_fde = NULL;
+                       }
+                       if (mpx_fde && mpx_fde->flags & TEVENT_FD_WRITE) {
+                               fde = mpx_fde;
+                               mpx_fde = NULL;
+                       }
+               }
+
+               if (mpx_fde) {
+                       /* Ensure we got the right fde. */
+                       if ((flags & fde->flags) == 0) {
+                               fde = mpx_fde;
+                               mpx_fde = NULL;
+                       }
+               }
+
+               /*
+                * make sure we only pass the flags
+                * the handler is expecting.
+                */
+               flags &= fde->flags;
                if (flags) {
                        fde->handler(epoll_ev->ev, fde, flags, fde->private_data);
                        break;
@@ -417,16 +779,58 @@ static int epoll_event_fd_destructor(struct tevent_fd *fde)
 {
        struct tevent_context *ev = fde->event_ctx;
        struct epoll_event_context *epoll_ev = NULL;
+       bool panic_triggered = false;
+       struct tevent_fd *mpx_fde = NULL;
+       int flags = fde->flags;
 
-       if (ev) {
-               epoll_ev = talloc_get_type(ev->additional_data,
-                                          struct epoll_event_context);
+       if (ev == NULL) {
+               return tevent_common_fd_destructor(fde);
+       }
 
-               epoll_check_reopen(epoll_ev);
+       epoll_ev = talloc_get_type_abort(ev->additional_data,
+                                        struct epoll_event_context);
 
-               epoll_del_event(epoll_ev, fde);
+       /*
+        * we must remove the event from the list
+        * otherwise a panic fallback handler may
+        * reuse invalid memory
+        */
+       DLIST_REMOVE(ev->fd_events, fde);
+
+       if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+               mpx_fde = talloc_get_type_abort(fde->additional_data,
+                                               struct tevent_fd);
+
+               fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
+               mpx_fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
+
+               fde->additional_data = NULL;
+               mpx_fde->additional_data = NULL;
+
+               fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
        }
 
+       epoll_ev->panic_state = &panic_triggered;
+       epoll_check_reopen(epoll_ev);
+       if (panic_triggered) {
+               return tevent_common_fd_destructor(fde);
+       }
+
+       if (mpx_fde != NULL) {
+               epoll_update_event(epoll_ev, mpx_fde);
+               if (panic_triggered) {
+                       return tevent_common_fd_destructor(fde);
+               }
+       }
+
+       fde->flags = 0;
+       epoll_update_event(epoll_ev, fde);
+       fde->flags = flags;
+       if (panic_triggered) {
+               return tevent_common_fd_destructor(fde);
+       }
+       epoll_ev->panic_state = NULL;
+
        return tevent_common_fd_destructor(fde);
 }
 
@@ -444,8 +848,7 @@ static struct tevent_fd *epoll_event_add_fd(struct tevent_context *ev, TALLOC_CT
        struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
                                                           struct epoll_event_context);
        struct tevent_fd *fde;
-
-       epoll_check_reopen(epoll_ev);
+       bool panic_triggered = false;
 
        fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
                                   handler, private_data,
@@ -454,7 +857,14 @@ static struct tevent_fd *epoll_event_add_fd(struct tevent_context *ev, TALLOC_CT
 
        talloc_set_destructor(fde, epoll_event_fd_destructor);
 
-       epoll_add_event(epoll_ev, fde);
+       epoll_ev->panic_state = &panic_triggered;
+       epoll_check_reopen(epoll_ev);
+       if (panic_triggered) {
+               return fde;
+       }
+       epoll_ev->panic_state = NULL;
+
+       epoll_update_event(epoll_ev, fde);
 
        return fde;
 }
@@ -466,6 +876,7 @@ static void epoll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
 {
        struct tevent_context *ev;
        struct epoll_event_context *epoll_ev;
+       bool panic_triggered = false;
 
        if (fde->flags == flags) return;
 
@@ -474,9 +885,14 @@ static void epoll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
 
        fde->flags = flags;
 
+       epoll_ev->panic_state = &panic_triggered;
        epoll_check_reopen(epoll_ev);
+       if (panic_triggered) {
+               return;
+       }
+       epoll_ev->panic_state = NULL;
 
-       epoll_change_event(epoll_ev, fde);
+       epoll_update_event(epoll_ev, fde);
 }
 
 /*
@@ -487,6 +903,7 @@ static int epoll_event_loop_once(struct tevent_context *ev, const char *location
        struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
                                                           struct epoll_event_context);
        struct timeval tval;
+       bool panic_triggered = false;
 
        if (ev->signal_events &&
            tevent_common_check_signal(ev)) {
@@ -503,7 +920,15 @@ static int epoll_event_loop_once(struct tevent_context *ev, const char *location
                return 0;
        }
 
+       epoll_ev->panic_state = &panic_triggered;
+       epoll_ev->panic_force_replay = true;
        epoll_check_reopen(epoll_ev);
+       if (panic_triggered) {
+               errno = EINVAL;
+               return -1;
+       }
+       epoll_ev->panic_force_replay = false;
+       epoll_ev->panic_state = NULL;
 
        return epoll_event_loop(epoll_ev, &tval);
 }
@@ -514,7 +939,7 @@ static const struct tevent_ops epoll_event_ops = {
        .set_fd_close_fn        = tevent_common_fd_set_close_fn,
        .get_fd_flags           = tevent_common_fd_get_flags,
        .set_fd_flags           = epoll_event_set_fd_flags,
-       .add_timer              = tevent_common_add_timer,
+       .add_timer              = tevent_common_add_timer_v2,
        .schedule_immediate     = tevent_common_schedule_immediate,
        .add_signal             = tevent_common_add_signal,
        .loop_once              = epoll_event_loop_once,