Test 2+2w+o-mb-o+o-wb-o

LISA 2+2w+o-mb-o+o-wb-o
(*
 * Allow per Linus Torvalds email:
 * http://www.spinics.net/lists/arm-kernel/msg483690.html
 *)
{
x = 0;
y = 0;
}
 P0           | P1           ;
 w[once] x 1  | w[once] y 1  ;
 f[mb]        | f[wmb]       ;
 w[once] y 2  | w[once] x 2  ;
Observed
    y=1; x=1;