From: Pavel Begunkov Date: Fri, 18 Nov 2022 15:41:41 +0000 (+0000) Subject: io_uring: disallow self-propelled ring polling X-Git-Tag: v6.6.17~6064^2~6 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7fdbc5f014c3f71bc44673a2d6c5bb2d12d45f25;p=platform%2Fkernel%2Flinux-rpi.git io_uring: disallow self-propelled ring polling When we post a CQE we wake all ring pollers as it normally should be. However, if a CQE was generated by a multishot poll request targeting its own ring, it'll wake that request up, which will make it to post a new CQE, which will wake the request and so on until it exhausts all CQ entries. Don't allow multishot polling io_uring files but downgrade them to oneshots, which was always stated as a correct behaviour that the userspace should check for. Cc: stable@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/3124038c0e7474d427538c2d915335ec28c92d21.1668785722.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- diff --git a/io_uring/poll.c b/io_uring/poll.c index c34019b..055632e 100644 --- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -246,6 +246,8 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked) continue; if (req->apoll_events & EPOLLONESHOT) return IOU_POLL_DONE; + if (io_is_uring_fops(req->file)) + return IOU_POLL_DONE; /* multishot, just fill a CQE and proceed */ if (!(req->flags & REQ_F_APOLL_MULTISHOT)) {