Test auto/RW-G+RW-R1+RW-G+RW-R1

LISA auto/RW-G+RW-R1+RW-G+RW-R1
(*
 * Result: Maybe
 * 
 * Process 0 starts (t=100000).
 * 
 * P0 advances one grace period (t=200000).
 * 
 * P1 -maybe- goes back a bit less than one grace period (t=101001).
 * 
 * P2 advances one grace period (t=201002).
 * 
 * P3 -maybe- goes back a bit less than one grace period (t=102003).
 * 
 * Process 0 start at t=100000, process 4 end at t=102003: Cycle forbidden.
 *)
{
}
 P0            | P1                 | P2            | P3                 ;
 r[once] r1 x0 | f[rcu_read_lock]   | r[once] r1 x2 | f[rcu_read_lock]   ;
 f[sync]       | r[once] r1 x1      | f[sync]       | r[once] r1 x3      ;
 w[once] x1 1  | f[rcu_read_unlock] | w[once] x3 1  | f[rcu_read_unlock] ;
               | w[once] x2 1       |               | w[once] x0 1       ;
Observed
    3:r1=1; 2:r1=0; 1:r1=1; 0:r1=1;