From: Pavel Begunkov <asml.silence@xxxxxxxxx>
commit 539bcb57da2f58886d7d5c17134236b0ec9cd15d upstream.
We may never try to process a poll wake and its mask if there was
multiple wake ups racing for queueing up a tw. Force
io_poll_check_events() to update the mask by vfs_poll().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: aa43477b04025 ("io_uring: poll rework")
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/00344d60f8b18907171178d7cf598de71d127b0b.1668710222.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/poll.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -226,6 +226,13 @@ static int io_poll_check_events(struct i
return IOU_POLL_DONE;
if (v & IO_POLL_CANCEL_FLAG)
return -ECANCELED;
+ /*
+ * cqe.res contains only events of the first wake up
+ * and all others are be lost. Redo vfs_poll() to get
+ * up to date state.
+ */
+ if ((v & IO_POLL_REF_MASK) != 1)
+ req->cqe.res = 0;
/* the mask was stashed in __io_poll_execute */
if (!req->cqe.res) {
