summaryrefslogtreecommitdiff
path: root/tools/memory-model/litmus-tests/SB+mbonceonces.litmus
blob: 74b874ffa8dadce5c9bb66015555dff7749d4b9e (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
31
32
C SB+mbonceonces

(*
 * Result: Never
 *
 * This litmus test demonstrates that full memory barriers suffice to
 * order the store-buffering pattern, where each process writes to the
 * variable that the preceding process reads.  (Locking and RCU can also
 * suffice, but not much else.)
 *)

{}

P0(int *x, int *y)
{
	int r0;

	WRITE_ONCE(*x, 1);
	smp_mb();
	r0 = READ_ONCE(*y);
}

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

	WRITE_ONCE(*y, 1);
	smp_mb();
	r0 = READ_ONCE(*x);
}

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