seccomp_user_notif.2: Note when FD indicates EOF/(E)POLLHUP in (e)poll/select

Verified by experiment.

Reported-by: Christian Brauner <christian.brauner@canonical.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man2/seccomp_user_notif.2 b/man2/seccomp_user_notif.2
index 29ed25eb206b60813779225769bde7fdb1717ed8..7a4b9d3b41753a34daf5a68e31c7add057cc0044 100644 (file)
--- a/man2/seccomp_user_notif.2
+++ b/man2/seccomp_user_notif.2
@@ -612,6 +612,16 @@ meaning that a notification response can be sent using the
 operation.
 .\" FIXME
 .\" But (how) is the writable/(E)POLLOUT useful?
+.IP \(bu
+After the last thread using the filter has terminated and been reaped using
+.BR waitpid (2)
+(or similar),
+the file descriptor indicates an end-of-file condition (readable in
+.BR select (2);
+.BR POLLHUP / EPOLLHUP
+in
+.BR poll (2)/
+.BR epoll_wait (2)).
 .SH BUGS
 If a
 .BR SECCOMP_IOCTL_NOTIF_RECV