diff options
| author | Visa Hankala <visa@cvs.openbsd.org> | 2021-12-20 16:24:33 +0000 |
|---|---|---|
| committer | Visa Hankala <visa@cvs.openbsd.org> | 2021-12-20 16:24:33 +0000 |
| commit | 9576a7d105b8dc8cde073ed524b8c938640eb67b (patch) | |
| tree | 83c43a6badb45f78c4b45d346e67f9a4578af130 | |
| parent | e0261a0fe1ba151aaee365fbfb4d2080ee71d66d (diff) | |
Make filt_dead() selectively inactive with EVFILT_EXCEPT
When a knote uses the dead event filter, the knote's file descriptor is
not supposed to point to an object with pending out-of-band data. Make
the knote inactive so that userspace will not receive a spurious event.
However, kqueue-based poll(2) should still receive HUP notifications.
This lets the system use dead_filtops with less strings attached
relative to the filter type.
| -rw-r--r-- | sys/kern/kern_event.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index fc86896c29c..109f7895455 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kern_event.c,v 1.176 2021/12/20 16:21:07 visa Exp $ */ +/* $OpenBSD: kern_event.c,v 1.177 2021/12/20 16:24:32 visa Exp $ */ /*- * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org> @@ -636,6 +636,17 @@ seltrue_kqfilter(dev_t dev, struct knote *kn) static int filt_dead(struct knote *kn, long hint) { + if (kn->kn_filter == EVFILT_EXCEPT) { + /* + * Do not deliver event because there is no out-of-band data. + * However, let HUP condition pass for poll(2). + */ + if ((kn->kn_flags & __EV_POLL) == 0) { + kn->kn_flags |= EV_DISABLE; + return (0); + } + } + kn->kn_flags |= (EV_EOF | EV_ONESHOT); if (kn->kn_flags & __EV_POLL) kn->kn_flags |= __EV_HUP; |