[vlc-devel] [PATCH 1/6] os2: implement vlc_once()

[KO Myung-Hun]

Rémi Denis-Courmont wrote:
> Le lundi 2 avril 2018, 12:28:59 EEST Kamil Rytarowski a écrit :
>> On 02.04.2018 08:58, Rémi Denis-Courmont wrote:
>>> Le lundi 2 avril 2018, 03:20:25 EEST Kamil Rytarowski a écrit :
>>>> Just follow an existing approach like in NetBSD:
>>>>      53 int
>>>>      54 pthread_once(pthread_once_t *once_control, void (*routine)(void))
>>>>      55 {
>>>>      56 	if (__predict_false(__uselibcstub))
>>>>      57 		return __libc_thr_once_stub(once_control, routine);
>>>>      58
>>>>      59 	if (once_control->pto_done == 0) {
>>>>      60 		pthread_mutex_lock(&once_control->pto_mutex);
>>>>      61 		pthread_cleanup_push(&once_cleanup, &once_control-
>> pto_mutex);
>>>>      62 		if (once_control->pto_done == 0) {
>>>>      63 			routine();
>>>>      64 			once_control->pto_done = 1;
>>>>      65 		}
>>>>      66 		pthread_cleanup_pop(1);
>>>>      67 	}
>>>>      68
>>>>      69 	return 0;
>>>>      70 }
>>>>
>>>> https://nxr.netbsd.org/xref/src/lib/libpthread/pthread_once.c#54
>>>
>>> This violates the memory model just like the first proposal.
>>
>> Please elaborate.
> 
> pto_done is accessed outside the memory model.
> 

Do you mean that pto_done should be in the block protected by mutex ?

-- 
KO Myung-Hun

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