On Mon, Jan 28, 2019 at 10:35 PM Jens Axboe <axboe@xxxxxxxxx> wrote:
> The submission queue (SQ) and completion queue (CQ) rings are shared
> between the application and the kernel. This eliminates the need to
> copy data back and forth to submit and complete IO.
[...]
> +static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx)
> +{
> + struct io_kiocb *req;
> +
> + /* safe to use the non tryget, as we're inside ring ref already */
> + percpu_ref_get(&ctx->refs);
Is that true? In the path io_sq_thread() -> io_submit_sqes() ->
io_submit_sqe() -> io_get_req(), I don't see anything that's already
holding a reference for you. Is the worker thread holding a reference
somewhere that I'm missing?
