> On Nov 7, 2019, at 3:09 PM, Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Thu, Nov 07, 2019 at 11:07:21PM +0000, Song Liu wrote:
>>
>>
>>>
>>>
>>>>> +
>>>>> +static int bpf_trampoline_update(struct bpf_prog *prog)
>>>>
>>>> Seems argument "prog" is not used at all?
>>>
>>> like one below ? ;)
>> e... I was really dumb... sorry..
>>
>> Maybe we should just pass the tr in?
>
> that would be imbalanced.
Hmm.. what do you mean by imbalanced?
>
>>>
>>>>> +{
>>>>> + struct bpf_trampoline *tr = prog->aux->trampoline;
>>>>> + void *old_image = tr->image + ((tr->selector + 1) & 1) * PAGE_SIZE/2;
>>>>> + void *new_image = tr->image + (tr->selector & 1) * PAGE_SIZE/2;
>>>>> + if (err)
>>>>> + goto out;
>>>>> + tr->selector++;
>>>>
>>>> Shall we do selector-- for unlink?
>>>
>>> It's a bit flip. I think it would be more confusing with --
>>
>> Right.. Maybe should use int instead of u64 for selector?
>
> No, since int can overflow.
I guess it is OK to overflow, no?
