On 8/14/19 3:35 AM, Jackie Liu wrote:
> Suppose there are three IOs here, and their order is as follows:
>
> Submit:
> [1] IO_LINK
> |
> |--- [2] IO_LINK | IO_DRAIN
> |
> |- [3] NORMAL_IO
>
> In theory, they all need to be inserted into the Link-list, but flag
> IO_DRAIN we have, io[2] and io[3] will be inserted into the defer_list,
> and finally, io[3] and io[2] will be processed at the same time.
>
> Now, it is directly forbidden to pass these two flags at the same time.
>
> Fixes: 9e645e1105c ("io_uring: add support for sqe links")
> Signed-off-by: Jackie Liu <liuyun01@xxxxxxxxxx>
> ---
> fs/io_uring.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index d542f1c..05ee628 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2074,10 +2074,13 @@ static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
> {
> struct io_uring_sqe *sqe_copy;
> struct io_kiocb *req;
> + unsigned int flags;
> int ret;
>
> + flags = READ_ONCE(s->sqe->flags);
> /* enforce forwards compatibility on users */
> - if (unlikely(s->sqe->flags & ~SQE_VALID_FLAGS)) {
> + if (unlikely((flags & ~SQE_VALID_FLAGS) ||
> + (flags & (IOSQE_IO_DRAIN | IOSQE_IO_LINK)))) {
This doesn't look right, as any setting of either DRAIN or LINK would now
fail?
Did you mean something ala:
if ((flags & (IOSQE_IO_DRAIN | IOSQE_IO_LINK)) ==
(IOSQE_IO_DRAIN | IOSQE_IO_LINK)) {
... fail ...
}
which makes me worried that you didn't test this at all...
--
Jens Axboe
