[RFC 2/3] nvme: passthrough helper with callback

[Kanchan Joshi]

On Wed, Mar 3, 2021 at 8:52 PM Chaitanya Kulkarni
<Chaitanya.Kulkarni at wdc.com> wrote:
>
> On 3/2/21 23:22, Kanchan Joshi wrote:
> > -void nvme_execute_passthru_rq(struct request *rq)
> > +void nvme_execute_passthru_rq_common(struct request *rq,
> > +                     rq_end_io_fn *done)
> >  {
> >       struct nvme_command *cmd = nvme_req(rq)->cmd;
> >       struct nvme_ctrl *ctrl = nvme_req(rq)->ctrl;
> > @@ -1135,9 +1136,17 @@ void nvme_execute_passthru_rq(struct request *rq)
> >       u32 effects;
> >
> >       effects = nvme_passthru_start(ctrl, ns, cmd->common.opcode);
> > -     blk_execute_rq(disk, rq, 0);
> > +     if (!done)
> > +             blk_execute_rq(disk, rq, 0);
> > +     else
> > +             blk_execute_rq_nowait(disk, rq, 0, done);
> >       nvme_passthru_end(ctrl, effects);
>
> This needs a detailed explanation in order to prove the correctness.

Do you see something wrong here?
blk_execute_rq() employs the same helper (i.e. nowait one) and uses
additional completion-variable to make it sync.