This is a note to let you know that I've just added the patch titled
io_uring: fix hanging iopoll in case of -EAGAIN
to the 5.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-fix-hanging-iopoll-in-case-of-eagain.patch
and it can be found in the queue-5.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7544a902aad6b1b080bd1bbce66093ca588218fc
Author: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Thu Jun 25 12:37:10 2020 +0300
io_uring: fix hanging iopoll in case of -EAGAIN
[ Upstream commit cd664b0e35cb1202f40c259a1a5ea791d18c879d ]
io_do_iopoll() won't do anything with a request unless
req->iopoll_completed is set. So io_complete_rw_iopoll() has to set
it, otherwise io_do_iopoll() will poll a file again and again even
though the request of interest was completed long time ago.
Also, remove -EAGAIN check from io_issue_sqe() as it races with
the changed lines. The request will take the long way and be
resubmitted from io_iopoll*().
io_kiocb's result and iopoll_completed")
Fixes: bbde017a32b3 ("io_uring: add memory barrier to synchronize
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1829be7f63a35..4ab1728de247c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1942,10 +1942,8 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
WRITE_ONCE(req->result, res);
/* order with io_poll_complete() checking ->result */
- if (res != -EAGAIN) {
- smp_wmb();
- WRITE_ONCE(req->iopoll_completed, 1);
- }
+ smp_wmb();
+ WRITE_ONCE(req->iopoll_completed, 1);
}
/*
@@ -5425,9 +5423,6 @@ static int io_issue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
if ((ctx->flags & IORING_SETUP_IOPOLL) && req->file) {
const bool in_async = io_wq_current_is_worker();
- if (req->result == -EAGAIN)
- return -EAGAIN;
-
/* workqueue context doesn't hold uring_lock, grab it now */
if (in_async)
mutex_lock(&ctx->uring_lock);
