From 539bcb57da2f58886d7d5c17134236b0ec9cd15d Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 17 Nov 2022 18:40:15 +0000 Subject: [PATCH] io_uring: fix tw losing poll events 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@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/00344d60f8b18907171178d7cf598de71d127b0b.1668710222.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/poll.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/io_uring/poll.c b/io_uring/poll.c index 90920ab..c34019b 100644 --- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -228,6 +228,13 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked) 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) { -- 2.7.4