On Tue, Aug 23, 2022 at 09:47:39AM -0600, Jens Axboe wrote:
>On 8/23/22 9:10 AM, Kanchan Joshi wrote:
>> If ->uring_cmd returned an error value different from -EAGAIN or
>> -EIOCBQUEUED, it gets overridden with IOU_OK. This invites trouble
>> as caller (io_uring core code) handles IOU_OK differently than other
>> error codes.
>> Fix this by returning the actual error code.
>
>Not sure if this is strictly needed, as the cqe error is set just
>fine. But I guess some places also check return value of the issue
>path.

So I was testing iopoll support and ran into this issue - submission
failed (expected one), control came back to this point, error code
got converted to IOU_OK, and it started polling endlessly for a command
that never got submitted.
io_issue_sqe continued to invoke io_iopoll_req_issued() rather than
bailing out.