LISA LISAq3R1G (* * Result: Never * * One RCU grace period and three RCU read-side critical sections. * This would normally allow cycles, but the release-acquire relationship * between P3 and P0 forces the entirety of P3 to precede the grace * period. Cycle prohibited. *) { 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[acquire] r2 x0 | f[sync] | r[once] r2 x2 | r[once] r3 x3 ; w[once] x1 1 | w[once] x2 1 | w[once] x3 1 | w[release] 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;