[ 023/108] epoll: clear the tfile_check_list on -ELOOP

From: Ben Hutchings
Date: Sun Jul 22 2012 - 21:45:28 EST

3.2-stable review patch. If anyone has any objections, please let me know.


From: Jason Baron <jbaron@xxxxxxxxxx>

commit 13d518074a952d33d47c428419693f63389547e9 upstream.

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 <jbaron@xxxxxxxxxx>
Reported-by: Yurij M. Plotnikov <Yurij.Plotnikov@xxxxxxxxxxxx>
Cc: Nelson Elhage <nelhage@xxxxxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Tested-by: Alexandra N. Kossovsky <Alexandra.Kossovsky@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
fs/eventpoll.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 739b098..c0b3c70 100644
--- 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);

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