r12153: work arround the fact that epoll reports EPOLLERR and EPOLLHUP, even if

you don't ask for.

with this patch the epoll mode behaves like the select mode

metze

diff --git a/source/lib/events/events_standard.c b/source/lib/events/events_standard.c
index abf17dd710b027bf59841d7a1087d0e4280a0254..df2368af3ea7ad5da5008da6f18d05fb02447430 100644 (file)
--- a/source/lib/events/events_standard.c
+++ b/source/lib/events/events_standard.c
@@ -119,6 +119,10 @@ static void epoll_init_ctx(struct std_event_context *std_ev, BOOL try_epoll)
        talloc_set_destructor(std_ev, epoll_ctx_destructor);
 }
 
+#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)
+
 /*
  add the epoll event to the given fd_event
 */
@@ -126,40 +130,100 @@ static void epoll_add_event(struct std_event_context *std_ev, struct fd_event *f
 {
        struct epoll_event event;
        if (std_ev->epoll_fd == -1) return;
+
+       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;
+
        ZERO_STRUCT(event);
        event.events = epoll_map_flags(fde->flags);
        event.data.ptr = fde;
        if (epoll_ctl(std_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) {
                epoll_fallback_to_select(std_ev, "EPOLL_CTL_ADD failed");
        }
+       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 & EVENT_FD_READ) {
+               fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
 }
 
 /*
- remove the epoll event for given fd_event
+ delete the epoll event for given fd_event
 */
-static void epoll_remove_event(struct std_event_context *std_ev, struct fd_event *fde)
+static void epoll_del_event(struct std_event_context *std_ev, struct fd_event *fde)
 {
        struct epoll_event event;
        if (std_ev->epoll_fd == -1) return;
+
+       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;
+
        ZERO_STRUCT(event);
        event.events = epoll_map_flags(fde->flags);
        event.data.ptr = fde;
        epoll_ctl(std_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event);
+       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
 }
 
 /*
  change the epoll event to the given fd_event
 */
-static void epoll_change_event(struct std_event_context *std_ev, struct fd_event *fde, uint16_t flags)
+static void epoll_mod_event(struct std_event_context *std_ev, struct fd_event *fde)
 {
        struct epoll_event event;
        if (std_ev->epoll_fd == -1) return;
+
+       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
        ZERO_STRUCT(event);
-       event.events = epoll_map_flags(flags);
+       event.events = epoll_map_flags(fde->flags);
        event.data.ptr = fde;
        if (epoll_ctl(std_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) {
                epoll_fallback_to_select(std_ev, "EPOLL_CTL_MOD failed");
        }
+
+       /* only if we want to read we want to tell the event handler about errors */
+       if (fde->flags & EVENT_FD_READ) {
+               fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+       }
+}
+
+static void epoll_change_event(struct std_event_context *std_ev, struct fd_event *fde)
+{
+       BOOL got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
+       BOOL want_read = (fde->flags & EVENT_FD_READ);
+       BOOL want_write= (fde->flags & EVENT_FD_WRITE);
+
+       if (std_ev->epoll_fd == -1) return;
+
+       fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+       /* there's already an event */
+       if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
+               if (want_read || (want_write && !got_error)) {
+                       epoll_mod_event(std_ev, fde);
+                       return;
+               }
+               /* 
+                * if we want to match the select behavior, we need to remove the epoll_event
+                * when the caller isn't interested in events.
+                *
+                * this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them
+                */
+               epoll_del_event(std_ev, fde);
+               return;
+       }
+
+       /* there's no epoll_event attached to the fde */
+       if (want_read || (want_write && !got_error)) {
+               epoll_add_event(std_ev, fde);
+               return;
+       }
 }
 
 /*
@@ -201,7 +265,20 @@ static int epoll_event_loop(struct std_event_context *std_ev, struct timeval *tv
                        epoll_fallback_to_select(std_ev, "epoll_wait() gave bad data");
                        return -1;
                }
-               if (events[i].events & (EPOLLHUP|EPOLLERR)) flags |= EVENT_FD_READ;
+               if (events[i].events & (EPOLLHUP|EPOLLERR)) {
+                       fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+                       /*
+                        * if we only wait for EVENT_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)) {
+                               epoll_del_event(std_ev, fde);
+                               continue;
+                       }
+                       flags |= EVENT_FD_READ;
+               }
                if (events[i].events & EPOLLIN) flags |= EVENT_FD_READ;
                if (events[i].events & EPOLLOUT) flags |= EVENT_FD_WRITE;
                if (flags) {
@@ -217,8 +294,8 @@ static int epoll_event_loop(struct std_event_context *std_ev, struct timeval *tv
 #else
 #define epoll_init_ctx(std_ev,try_epoll) if (try_epoll) {/* fix unused variable warning*/}
 #define epoll_add_event(std_ev,fde)
-#define epoll_remove_event(std_ev,fde)
-#define epoll_change_event(std_ev,fde,flags)
+#define epoll_del_event(std_ev,fde)
+#define epoll_change_event(std_ev,fde)
 #define epoll_event_loop(std_ev,tvalp) (-1)
 #endif
 
@@ -280,7 +357,7 @@ static int std_event_fd_destructor(void *ptr)
        DLIST_REMOVE(std_ev->fd_events, fde);
        std_ev->destruction_count++;
 
-       epoll_remove_event(std_ev, fde);
+       epoll_del_event(std_ev, fde);
 
        return 0;
 }
@@ -342,9 +419,9 @@ static void std_event_set_fd_flags(struct fd_event *fde, uint16_t flags)
        ev = fde->event_ctx;
        std_ev = talloc_get_type(ev->additional_data, struct std_event_context);
 
-       epoll_change_event(std_ev, fde, flags);
-
        fde->flags = flags;
+
+       epoll_change_event(std_ev, fde);
 }
 
 /*