On Tue, Aug 18, 2020 at 11:37:45AM +0200, Petr Machata wrote:
> Ido Schimmel <ido...@idosch.org> writes:
> > On Mon, Aug 17, 2020 at 10:38:24AM -0500, Bjorn Helgaas wrote:
> >> You've likely seen this already, but Coverity found this problem:
> >>
> >> *** CID 1466147: Control flow issues (DEADCODE)
> >> /drivers/net/ethernet/mellanox/mlxsw/spectrum_policer.c: 380 in
> >> mlxsw_sp_policers_init()
> >> 374 }
> >> 375
> >> 376 return 0;
> >> 377
> >> 378 err_family_register:
> >> 379 for (i--; i >= 0; i--) {
> >> >>> CID 1466147: Control flow issues (DEADCODE)
> >> >>> Execution cannot reach this statement: "struct
> >> mlxsw_sp_policer_fam...".
> >> 380 struct mlxsw_sp_policer_family *family;
> >> 381
> >> 382 family = mlxsw_sp->policer_core->family_arr[i];
> >> 383 mlxsw_sp_policer_family_unregister(mlxsw_sp, family);
> >> 384 }
> >> 385 err_init:
> >>
> >> I think the problem is that MLXSW_SP_POLICER_TYPE_MAX is 0 because
> >>
> >> > +enum mlxsw_sp_policer_type {
> >> > + MLXSW_SP_POLICER_TYPE_SINGLE_RATE,
> >> > +
> >> > + __MLXSW_SP_POLICER_TYPE_MAX,
> >> > + MLXSW_SP_POLICER_TYPE_MAX = __MLXSW_SP_POLICER_TYPE_MAX - 1,
> >> > +};
> >>
> >> so we can only execute the family_register loop once, with i == 0,
> >> and if we get to err_family_register via the error exit:
> >>
> >> > + for (i = 0; i < MLXSW_SP_POLICER_TYPE_MAX + 1; i++) {
> >> > + err = mlxsw_sp_policer_family_register(mlxsw_sp,
> >> > mlxsw_sp_policer_family_arr[i]);
> >> > + if (err)
> >> > + goto err_family_register;
> >>
> >> i will be 0, so i-- sets i to -1, so we don't enter the
> >> family_unregister loop body since -1 is not >= 0.
> >
> > Thanks for the report, but isn't the code doing the right thing here? I
> > mean, it's dead code now, but as soon as we add another family it will
> > be executed. It seems error prone to remove it only to please Coverity
> > and then add it back when it's actually needed.
>
> Agreed.
You're right, I missed the forest for the trees. Sorry for the noise.
Bjorn
