Re: [RFC PATCH v1 2/2] chnet: Implement `get_thread()` and `put_thread()` function

[Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>]

On Mon, Aug 29, 2022 at 12:29 PM Ammar Nofan Faizi wrote:
> On 8/29/22 12:24 PM, Alviro Iskandar Setiawan wrote:
>> On Mon, Aug 29, 2022 at 12:17 PM Alviro Iskandar Setiawan wrote:
>>> On Mon, Aug 29, 2022 at 11:54 AM Ammar Nofan Faizi wrote:
>>>> On 8/29/22 11:41 AM, Alviro Iskandar Setiawan wrote:
>>>>> On Mon, Aug 29, 2022 at 8:11 AM Ammar Faizi wrote:
>>>>>> +static base::Thread *get_thread(void)
>>>>>> +{
>>>>>> +       const uint32_t max_ch_thpool = g_max_ch_thpool;
>>>>>> +       const uint32_t nr_ref_split = 2048;
>>>>>> +       struct ch_thpool **thp;
>>>>>> +       struct ch_thpool *ret = nullptr;
>>>>>> +       struct ch_thpool *tmp;
>>>>>> +       uint32_t min_ref_idx;
>>>>>> +       uint32_t min_ref;
>>>>>> +       uint32_t i;
>>>>>> +
>>>>>> +       g_thpool_lock_.lock();
>>>>>> +       thp = g_thpool;
>>>>>> +       if (!thp) {
>>>>>> +               g_thpool_lock_.unlock();
>>>>>> +               return nullptr;
>>>>>> +       }
>>>>>
>>>>> in what situation @thp can be nullptr?
>>>>
>>>> When the chnet_global_destroy() is called.
>>
>> btw, i missed a case on the chnet construction, you do
>>
>>     thread_(*get_thread()),
>>
>> if get_thread() returns a nullptr, the @thread_ will become a
>> reference to a nullptr, it will definitely break, how do you handle
>> this?
>
> I don't think we need to handle that. If @thp ever be a nullptr in a
> get_thread() call, then it's a misuse of the API. We must never call
> get_thread() after chnet_global_destroy() is called. It doesn't make
> much sense to have this situation.

if this should never happen, then why do you do a null check there?
your null check doesn't make much sense too! why are we returning
nullptr if we exactly know that the caller will randomly fault if that
happens, i can't accept your reasoning

-- Viro