[PATCH 5.6 101/161] io_uring: fix mismatched finish_wait() calls in io_uring_cancel_files()

[Greg Kroah-Hartman]

From: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>

commit d8f1b9716cfd1a1f74c0fedad40c5f65a25aa208 upstream.

The prepare_to_wait() and finish_wait() calls in io_uring_cancel_files()
are mismatched. Currently I don't see any issues related this bug, just
find it by learning codes.

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/io_uring.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6488,11 +6488,9 @@ static int io_uring_release(struct inode
 static void io_uring_cancel_files(struct io_ring_ctx *ctx,
 				  struct files_struct *files)
 {
-	struct io_kiocb *req;
-	DEFINE_WAIT(wait);
-
 	while (!list_empty_careful(&ctx->inflight_list)) {
-		struct io_kiocb *cancel_req = NULL;
+		struct io_kiocb *cancel_req = NULL, *req;
+		DEFINE_WAIT(wait);
 
 		spin_lock_irq(&ctx->inflight_lock);
 		list_for_each_entry(req, &ctx->inflight_list, inflight_entry) {
@@ -6532,6 +6530,7 @@ static void io_uring_cancel_files(struct
 			 */
 			if (refcount_sub_and_test(2, &cancel_req->refs)) {
 				io_put_req(cancel_req);
+				finish_wait(&ctx->inflight_wait, &wait);
 				continue;
 			}
 		}
@@ -6539,8 +6538,8 @@ static void io_uring_cancel_files(struct
 		io_wq_cancel_work(ctx->io_wq, &cancel_req->work);
 		io_put_req(cancel_req);
 		schedule();
+		finish_wait(&ctx->inflight_wait, &wait);
 	}
-	finish_wait(&ctx->inflight_wait, &wait);
 }
 
 static int io_uring_flush(struct file *file, void *data)