On Linux 2.6.8 and older, epoll_ctl(EPOLL_CTL_DEL) requires a poll_event

even though it is not used, and will return EFAULT if one is not provided.

Also, instead of silently accepting EBADF from epoll_ctl(), check that
sp->fd != -1 before calling vca_del().  This can happen in some cases
where vca_pollsession() closes the session before returning.  This way,
we will still get an assertion failure if epoll_ctl() fails for some
other (unexpected) reason.

Thanks to airmax for his assistance in tracking this down.

git-svn-id: http://www.varnish-cache.org/svn/trunk@1143 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/cache_acceptor_epoll.c

@@ -62,10 +62,8 @@ vca_add(int fd, void *data)
 static void
 vca_del(int fd)
 {
-	int i;
-
-	i = epoll_ctl(epfd, EPOLL_CTL_DEL, fd, NULL);
-	assert(i == 0 || errno == EBADF);
+	struct epoll_event ev = { 0, { 0 } };
+	AZ(epoll_ctl(epfd, EPOLL_CTL_DEL, fd, &ev));
 }
 
 static void
@@ -103,6 +101,7 @@ vca_main(void *arg)
 				i = vca_pollsession(sp);
 				if (i >= 0) {
 					TAILQ_REMOVE(&sesshead, sp, list);
+					if (sp->fd != -1)
 						vca_del(sp->fd);
 					if (i == 0)
 						vca_handover(sp, i);