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

[Rémi Denis-Courmont]

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.

-- 
Rémi Denis-Courmont