Test LISA3R1Gq

LISA LISA3R1Gq
(*
 * Result: Sometimes
 *
 * One grace period and three RCU read-side critical sections.  Ordering
 * from the RCU grace period to P2 could prohibit cycles, except that P3's
 * RCU read-side critical section still allows the needed misordering.
 * The reason that this ordering is not completely redundant with the
 * grace period is that it forces P2's critical section to completely
 * follow the grace period.  Cycle allowed.
 *)
{
x0 = 0;
x1 = 0;
x2 = 0;
x3 = 0;
}
 P0                 | P1              | P2                 | P3                 ;
 f[rcu_read_lock]   | r[once] r1 x1   | f[rcu_read_lock]   | f[rcu_read_lock]   ;
 r[once] r2 x0      | f[sync]         | r[acquire] r2 x2   | r[once] r3 x3      ;
 w[once] x1 1       | w[release] x2 1 | w[once] x3 1       | w[once] x0 1       ;
 f[rcu_read_unlock] |                 | f[rcu_read_unlock] | f[rcu_read_unlock] ;
Observed
    3:r3=1; 2:r2=1; 1:r1=0; 0:r2=1;