0001 C RCU+sync+read
0002
0003 (*
0004 * Result: Never
0005 *
0006 * This litmus test demonstrates that after a grace period, an RCU updater always
0007 * sees all stores done in prior RCU read-side critical sections. Such
0008 * read-side critical sections would have ended before the grace period ended.
0009 *
0010 * This is one implication of the RCU grace-period guarantee, which says (among
0011 * other things) that an RCU read-side critical section cannot span a grace period.
0012 *)
0013
0014 {
0015 int x = 0;
0016 int y = 0;
0017 }
0018
0019 P0(int *x, int *y)
0020 {
0021 rcu_read_lock();
0022 WRITE_ONCE(*x, 1);
0023 WRITE_ONCE(*y, 1);
0024 rcu_read_unlock();
0025 }
0026
0027 P1(int *x, int *y)
0028 {
0029 int r0;
0030 int r1;
0031
0032 r0 = READ_ONCE(*x);
0033 synchronize_rcu();
0034 r1 = READ_ONCE(*y);
0035 }
0036
0037 exists (1:r0=1 /\ 1:r1=0)
