On Tue, Jun 24, 2025 at 7:26 PM Ming Lei <ming.lei@xxxxxxxxxx> wrote:
>
> ublk_queue_cmd_list() dispatches the whole batch list by scheduling task
> work via the tail request's io_uring_cmd, this way is fine even though
> more than one io_ring_ctx are involved for this batch since it is just
> one running context.
>
> However, the task work handler ublk_cmd_list_tw_cb() takes `issue_flags`
> of tail uring_cmd's io_ring_ctx for completing all commands. This way is
> wrong if any uring_cmd is issued from different io_ring_ctx.
>
> Fixes it by always building batch IOs from same io_ring_ctx and io task
> because ublk_dispatch_req() does validate task context, and IO needs to
> be aborted in case of running from fallback task work context.
>
> For typical per-queue or per-io daemon implementation, this way shouldn't
> make difference from performance viewpoint, because single io_ring_ctx is
> taken in each daemon for normal use case.
>
> Fixes: d796cea7b9f3 ("ublk: implement ->queue_rqs()")
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Caleb Sander Mateos <csander@xxxxxxxxxxxxxxx>
