Re: [dpdk-dev] [PATCH] bpf: delete meaningless code

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

 
> 
> 在 2021/4/21 19:43, Ananyev, Konstantin 写道:
> >>
> >> 'rd->u.max = rd->u.max' is meaningless which should be deleted.
> >>
> >> This patch fixed it.
> >>
> >> Fixes: 8021917293d0 ("bpf: add extra validation for input BPF program")
> >> Cc: stable@dpdk.org
> >
> > As I remember, I did it on purpose.
> > Some old (but still supported) version of clang complained
> > about unitialized variable.
> 
> Well, how about like this ?
> 		uint64_t tmp = rd->u.max;
> 		if (op == BPF_MOD)
> 			tmp = RTE_MIN(tmp, tmp - 1);
> 		rd->u.max = tmp;


Then, I think it should be:
tmp = RTE_MIN(tmp, rs->u.max - 1);

Or just leave things as they are right now.
Nothing is broken here.

> >
> >> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> >> ---
> >>   lib/librte_bpf/bpf_validate.c | 2 --
> >>   1 file changed, 2 deletions(-)
> >>
> >> diff --git a/lib/librte_bpf/bpf_validate.c b/lib/librte_bpf/bpf_validate.c
> >> index 9214f15..c5ad951 100644
> >> --- a/lib/librte_bpf/bpf_validate.c
> >> +++ b/lib/librte_bpf/bpf_validate.c
> >> @@ -517,8 +517,6 @@ eval_divmod(uint32_t op, struct bpf_reg_val *rd, struct bpf_reg_val *rs,
> >>   	} else {
> >>   		if (op == BPF_MOD)
> >>   			rd->u.max = RTE_MIN(rd->u.max, rs->u.max - 1);
> >> -		else
> >> -			rd->u.max = rd->u.max;
> >>   		rd->u.min = 0;
> >>   	}
> >>
> >> --
> >> 2.7.4
> >
> > .
> >