On 24. Jun 2024, at 13:16, Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> On Mon, 2024-06-24 at 21:54 +0200, Thorsten Blum wrote:
>> Explicitly test the iterator variable i > 0 to fix the following
>> Coccinelle/coccicheck error reported by itnull.cocci:
>>
>> ERROR: iterator variable bound on line 4688 cannot be NULL
>>
>> Compile-tested only.
>>
>> Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxxx>
>> ---
>> kernel/bpf/btf.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
>> index 821063660d9f..7720f8967814 100644
>> --- a/kernel/bpf/btf.c
>> +++ b/kernel/bpf/btf.c
>> @@ -4687,7 +4687,7 @@ static void btf_datasec_show(const struct btf *btf,
>> __btf_name_by_offset(btf, t->name_off));
>> for_each_vsi(i, t, vsi) {
>> var = btf_type_by_id(btf, vsi->type);
>> - if (i)
>> + if (i > 0)
>> btf_show(show, ",");
>> btf_type_ops(var)->show(btf, var, vsi->type,
>> data + vsi->offset, bits_offset, show);
>
> Could you please elaborate a bit?
> Here is for_each_vsi is defined:
>
> #define for_each_vsi(i, datasec_type, member) \
> for (i = 0, member = btf_type_var_secinfo(datasec_type); \
> i < btf_type_vlen(datasec_type); \
> i++, member++)
>
> Here it sets 'i' to zero for the first iteration.
> Why would the tool report that 'i' can't be zero?
Coccinelle thinks i can't be a NULL pointer (not the number zero). It's
essentially a false-positive warning, but since there are only 4 such
warnings under kernel/, I thought it would be worthwhile to remove some
of them by making the tests explicit.
