Test auto/RR-GR2+RR-R

LISA auto/RR-GR2+RR-R
(*
 * Result: Never
 * 
 * Process 0 starts (t=100000).
 * 
 * P0 advances one grace period (t=200000).
 * 
 * P1 goes back a bit less than one grace period (t=101001).
 * 
 * Process 0 start at t=100000, process 2 end at t=101001: Cycle forbidden.
 *)
{
}
 P0                 | P1                 | P2           ;
 r[once] r1 x0      | f[rcu_read_lock]   | w[once] x0 1 ;
 f[sync]            | r[once] r1 x1      | w[once] x1 1 ;
 f[rcu_read_lock]   | r[once] r2 x0      |              ;
 r[once] r2 x1      | f[rcu_read_unlock] |              ;
 f[rcu_read_unlock] |                    |              ;
Observed
    1:r2=1; 1:r1=1; 0:r2=0; 0:r1=1;
and 1:r2=1; 1:r1=0; 0:r2=0; 0:r1=1;