summaryrefslogtreecommitdiffstats
path: root/tools/memory-model/litmus-tests/R+fencembonceonces.litmus
blob: 222a0b850b4a5d98d087c2d94ab5158e928c43ae (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
C R+fencembonceonces

(*
 * Result: Never
 *
 * This is the fully ordered (via smp_mb()) version of one of the classic
 * counterintuitive litmus tests that illustrates the effects of store
 * propagation delays.  Note that weakening either of the barriers would
 * cause the resulting test to be allowed.
 *)

{}

P0(int *x, int *y)
{
	WRITE_ONCE(*x, 1);
	smp_mb();
	WRITE_ONCE(*y, 1);
}

P1(int *x, int *y)
{
	int r0;

	WRITE_ONCE(*y, 2);
	smp_mb();
	r0 = READ_ONCE(*x);
}

exists (y=2 /\ 1:r0=0)