[PATCH v2] io_uring: fix overflowed reqs cancellation

[PATCH v2] io_uring: fix overflowed reqs cancellation

[Pavel Begunkov]

Overflowed requests in io_uring_cancel_files() should be shed only of
inflight and overflowed refs. All other left references are owned by
someone else.

If refcount_sub_and_test() fails, it will go further and put put extra
ref, don't do that. Also, don't need to do io_wq_cancel_work()
for overflowed reqs, they will be let go shortly anyway.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---

v2: don't schedule() if requests is already freed

 fs/io_uring.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index bc5117ee6ce3..b1c30284efbf 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7447,10 +7447,11 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
 				finish_wait(&ctx->inflight_wait, &wait);
 				continue;
 			}
+		} else {
+			io_wq_cancel_work(ctx->io_wq, &cancel_req->work);
+			io_put_req(cancel_req);
 		}
 
-		io_wq_cancel_work(ctx->io_wq, &cancel_req->work);
-		io_put_req(cancel_req);
 		schedule();
 		finish_wait(&ctx->inflight_wait, &wait);
 	}
-- 
2.24.0

Re: [PATCH v2] io_uring: fix overflowed reqs cancellation

[Jens Axboe]

On 5/30/20 5:19 AM, Pavel Begunkov wrote:
> Overflowed requests in io_uring_cancel_files() should be shed only of
> inflight and overflowed refs. All other left references are owned by
> someone else.
> 
> If refcount_sub_and_test() fails, it will go further and put put extra
> ref, don't do that. Also, don't need to do io_wq_cancel_work()
> for overflowed reqs, they will be let go shortly anyway.

Applied, thanks.

-- 
Jens Axboe