If while calling sys_ppoll with zero timeout we had received a signal,
we do return -EINTR.
FMPOV the -EINTR should specify that we were interrupted by the signal,
and not that we have a pending signal which does not interfere with us
at all as we were planning to return anyway. We can just return 0 in
these case.
I understand that it is a rare situation that signal comes to us while
in poll with zero timeout, but that reproduced somehow on VZ7 kernel on
CRIU tests.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx>
---
fs/select.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/select.c b/fs/select.c
index 53a0c149f528..54d523e3de7f 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -873,7 +873,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
{
poll_table* pt = &wait->pt;
ktime_t expire, *to = NULL;
- int timed_out = 0, count = 0;
+ int timed_out = 0, no_timeout = 0, count = 0;
u64 slack = 0;
__poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
unsigned long busy_start = 0;
@@ -881,10 +881,10 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
/* Optimise the no-wait case */
if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
pt->_qproc = NULL;
- timed_out = 1;
+ no_timeout = 1;
}
- if (end_time && !timed_out)
+ if (end_time && !no_timeout)
slack = select_estimate_accuracy(end_time);
for (;;) {
@@ -921,10 +921,10 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
pt->_qproc = NULL;
if (!count) {
count = wait->error;
- if (signal_pending(current))
+ if (!no_timeout && signal_pending(current))
count = -ERESTARTNOHAND;
}
- if (count || timed_out)
+ if (count || timed_out || no_timeout)
break;
/* only if found POLL_BUSY_LOOP sockets && not out of time */
--
2.21.0
