Re: PATCH: Add memory barrier to malloc

[Dan Kegel <dank at kegel dot com>]

Momchil Velikov wrote:
> > > > > > "H.J. Lu" == H J Lu <hjl@lucon.org> writes:
>
>     H.J. Lu> --- libc/malloc/arena.c.barrier	2002-12-26 16:36:41.000000000 -0800
>     H.J. Lu> +++ libc/malloc/arena.c	2003-05-03 23:56:59.000000000 -0700
>     H.J. Lu> @@ -758,6 +758,7 @@ arena_get2(a_tsd, size) mstate a_tsd; si
>     H.J. Lu>    /* Add the new arena to the global list.  */
>     H.J. Lu>    (void)mutex_lock(&list_lock);
>     H.J. Lu>    a->next = main_arena.next;
>     H.J. Lu> +  atomic_write_barrier ();
>     H.J. Lu>    main_arena.next = a;
>     H.J. Lu>    (void)mutex_unlock(&list_lock);
>
> Why would a barrier be needed inside a critical section ? Aren't POSIX
> memory model guarantees sufficient ?

I guess list_lock doesn't protect accesses to main_arena?
- Dan

--
Dan Kegel
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