erts: Don't use EV_DISPATCH on openbsd

Currently (OpenBSD 6.2) the kqueu implementation on
opnebsd does not work properly for EOF conditions when
using EV_DISPATCH, so we use the EV_ONESHOT fallback there.

1 files changed, 8 insertions, 4 deletions

diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index 7aa53e8f36..ced8a4a2a7 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -782,10 +782,14 @@ update_pollset(ErtsPollSet *ps, int fd, ErtsPollOp op, ErtsPollEvents events)
     struct kevent evts[2];
     struct timespec ts = {0, 0};
 
-#ifdef EV_DISPATCH
-    /* If we have EV_DISPATCH we use it. The kevent descriptions for both
-       read and write are added on OP_ADD and removed on OP_DEL. And then
-       after than only EV_ENABLE|EV_DISPATCH are used.
+#if defined(EV_DISPATCH) && !defined(__OpenBSD__)
+    /* If we have EV_DISPATCH we use it, unless we are on OpenBSD as the
+       behavior of EV_EOF seems to be edge triggered there and we need it
+       to be level triggered.
+
+       The kevent descriptions for both read and write are added on OP_ADD
+       and removed on OP_DEL. And then after than only EV_ENABLE|EV_DISPATCH
+       are used.
 
        It could be possible to not modify the pollset when disabling and/or
        deleting events, but that may cause the poll threads to be awoken