mirror of https://gitee.com/openkylin/linux.git
31 lines
494 B
Plaintext
31 lines
494 B
Plaintext
C R+mbonceonces
|
|
|
|
(*
|
|
* 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)
|