LISA cris-crossing read-side critical sections (* * Result: Sometimes *) { } P0 | P1 | P2 ; f[rcu_read_lock] | r[once] r1 y | r[once] r2 z ; w[once] x 1 | w[once] z r1 | f[rmb] ; f[rcu_read_unlock] | | r[once] r3 x ; f[wmb] | | ; w[once] y 1 | | ; Observed 2:r3=0; 2:r2=1; 1:r1=1;