Re: [PATCH] i40iw: Use fallthrough pseudo-keyword

[Leon Romanovsky <leon@kernel.org>]

On Sun, May 09, 2021 at 08:12:42PM +0800, 陳偉銘 wrote:
> Hi,
> 
> thanks for reply
> 
> the purpose for the patch is to follow the regulation in this doc(
> https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through
> )
> 
> the following paragraph is written in the doc:
> [image: image.png]
> 
> Not sure if I misunderstood anything, or actually we don't need to follow
> the regulation if no code in "case"?

Please don't top-post, use HTML emails and always CC mailing list.

I'm saying that there is a difference between two following snippets:
switch (value) {
case STATE_ONE:
        do_something();
case STATE_TWO:
        do_other();
        break;
default:
        WARN("unknown state");
}
and 

switch (value) {
case STATE_ONE:
case STATE_TWO:
        do_other();
        break;
default:
        WARN("unknown state");
}

While the first one needs "fallthrough" keyword, the second one doesn't.

Thanks

> 
> Thanks
> 
> Wei Ming Chen
> 
> Leon Romanovsky <leon@kernel.org> 於 2021年5月9日 週日 下午6:50寫道：
> 
> > On Sun, May 09, 2021 at 04:31:35PM +0800, Wei Ming Chen wrote:
> > > Add pseudo-keyword macro fallthrough[1]
> > >
> > > [1]
> > https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through
> > >
> > > Signed-off-by: Wei Ming Chen <jj251510319013@gmail.com>
> > > ---
> > >  drivers/infiniband/hw/i40iw/i40iw_ctrl.c | 1 +
> > >  drivers/infiniband/hw/i40iw/i40iw_uk.c   | 1 +
> > >  2 files changed, 2 insertions(+)
> >
> > What exactly are you fixing?
> > "case" without any code doesn't need "fallthrough".
> >
> > Thanks
> >
> > >
> > > diff --git a/drivers/infiniband/hw/i40iw/i40iw_ctrl.c
> > b/drivers/infiniband/hw/i40iw/i40iw_ctrl.c
> > > index eaea5d545eb8..c6081283217c 100644
> > > --- a/drivers/infiniband/hw/i40iw/i40iw_ctrl.c
> > > +++ b/drivers/infiniband/hw/i40iw/i40iw_ctrl.c
> > > @@ -2454,6 +2454,7 @@ static enum i40iw_status_code
> > i40iw_sc_qp_init(struct i40iw_sc_qp *qp,
> > >                       return ret_code;
> > >               break;
> > >       case 5: /* fallthrough until next ABI version */
> > > +             fallthrough;
> > >       default:
> > >               if (qp->qp_uk.max_rq_frag_cnt >
> > I40IW_MAX_WQ_FRAGMENT_COUNT)
> > >                       return I40IW_ERR_INVALID_FRAG_COUNT;
> > > diff --git a/drivers/infiniband/hw/i40iw/i40iw_uk.c
> > b/drivers/infiniband/hw/i40iw/i40iw_uk.c
> > > index f521be16bf31..e1c318c291c0 100644
> > > --- a/drivers/infiniband/hw/i40iw/i40iw_uk.c
> > > +++ b/drivers/infiniband/hw/i40iw/i40iw_uk.c
> > > @@ -1004,6 +1004,7 @@ enum i40iw_status_code i40iw_qp_uk_init(struct
> > i40iw_qp_uk *qp,
> > >                       i40iw_get_wqe_shift(info->max_rq_frag_cnt, 0,
> > &rqshift);
> > >                       break;
> > >               case 5: /* fallthrough until next ABI version */
> > > +                     fallthrough;
> > >               default:
> > >                       rqshift = I40IW_MAX_RQ_WQE_SHIFT;
> > >                       break;
> > > --
> > > 2.25.1
> > >
> >