epoll_ctl.2: Document ELOOP error for circular monitoring loops

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man2/epoll_ctl.2 b/man2/epoll_ctl.2
index dace16c07df6c90750c1cd247241a091919762b0..476b36770bef2625c4416b8c7688bbf34eed9beb 100644 (file)
--- a/man2/epoll_ctl.2
+++ b/man2/epoll_ctl.2
@@ -224,6 +224,13 @@ or the requested operation
 .I op
 is not supported by this interface.
 .TP
+.B ELOOP
+.I fd
+refers to an epoll instance and this
+.B EPOLL_CTL_ADD
+operation would result in a circular loop of epoll instances
+monitoring one another.
+.TP
 .B ENOENT
 .I op
 was