epoll: clear the tfile_check_list on -ELOOP

An epoll_ctl(,EPOLL_CTL_ADD,,) operation can return '-ELOOP' to prevent
circular epoll dependencies from being created.  However, in that case we
do not properly clear the 'tfile_check_list'.  Thus, add a call to
clear_tfile_check_list() for the -ELOOP case.

Signed-off-by: Jason Baron <[email protected]>
Reported-by: Yurij M. Plotnikov <[email protected]>
Cc: Nelson Elhage <[email protected]>
Cc: Davide Libenzi <[email protected]>
Tested-by: Alexandra N. Kossovsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 739b0985b398ea2d837af83e26fa305a6cdfdc30..c0b3c70ee87a2b8e0e46c01a87d63ac692aecc71 100644 (file)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1663,8 +1663,10 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
        if (op == EPOLL_CTL_ADD) {
                if (is_file_epoll(tfile)) {
                        error = -ELOOP;
-                       if (ep_loop_check(ep, tfile) != 0)
+                       if (ep_loop_check(ep, tfile) != 0) {
+                               clear_tfile_check_list();
                                goto error_tgt_fput;
+                       }
                } else
                        list_add(&tfile->f_tfile_llink, &tfile_check_list);
        }