epoll: massage the check list insertion

in the "non-epoll target" cases do it in ep_insert() rather than
in do_epoll_ctl(), so that we do it only with some epitem is already
guaranteed to exist.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-10-01 16:10:11 -04:00
commit d9f41e3c95