[PATCH 5.10 002/103] io_uring: synchronise IOPOLL on task_submit fail

Greg Kroah-Hartman
2021-01-15T12:49:29Z

From: Pavel Begunkov <asml.silence@gmail.com>

commit 81b6d05ccad4f3d8a9dfb091fb46ad6978ee40e4 upstream

io_req_task_submit() might be called for IOPOLL, do the fail path under
uring_lock to comply with IOPOLL synchronisation based solely on it.

Cc: stable@vger.kernel.org # 5.5+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/io_uring.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1f798c5c4213e..3974b4f124b6a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2047,14 +2047,15 @@ static void io_req_task_cancel(struct callback_head *cb)
static void __io_req_task_submit(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
+ bool fail;

- if (!__io_sq_thread_acquire_mm(ctx)) {
- mutex_lock(&ctx->uring_lock);
+ fail = __io_sq_thread_acquire_mm(ctx);
+ mutex_lock(&ctx->uring_lock);
+ if (!fail)
__io_queue_sqe(req, NULL);
- mutex_unlock(&ctx->uring_lock);
- } else {
+ else
__io_req_task_cancel(req, -EFAULT);
- }
+ mutex_unlock(&ctx->uring_lock);
}

static void io_req_task_submit(struct callback_head *cb)
--
2.27.0