From: Jens Axboe <axboe@kernel.dk>
Date: Thu, 15 Apr 2021 15:47:13 +0000 (-0600)
Subject: io_uring: disable multishot poll for double poll add cases
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ea6a693d862d4f0edd748a1fa3fc6faf2c39afb2;p=linux.git

io_uring: disable multishot poll for double poll add cases

The re-add handling isn't correct for the multi wait case, so let's
just disable it for now explicitly until we can get that sorted out. This
just turns it into a one-shot request. Since we pass back whether or not
a poll request terminates in multishot mode on completion, this should
not break properly behaving applications that check for IORING_CQE_F_MORE
on completion.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ab14692b05b41..4803e31e93012 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4976,6 +4976,12 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
 			pt->error = -EINVAL;
 			return;
 		}
+		/*
+		 * Can't handle multishot for double wait for now, turn it
+		 * into one-shot mode.
+		 */
+		if (!(req->poll.events & EPOLLONESHOT))
+			req->poll.events |= EPOLLONESHOT;
 		/* double add on the same waitqueue head, ignore */
 		if (poll->head == head)
 			return;