36 lines
719 B
Plaintext
36 lines
719 B
Plaintext
|
C LB+unlocklockonceonce+poacquireonce
|
||
|
|
|
||
|
|
(*
|
||
|
|
* Result: Never
|
||
|
|
*
|
||
|
|
* If two locked critical sections execute on the same CPU, all accesses
|
||
|
|
* in the first must execute before any accesses in the second, even if the
|
||
|
|
* critical sections are protected by different locks. Note: Even when a
|
||
|
|
* write executes before a read, their memory effects can be reordered from
|
||
|
|
* the viewpoint of another CPU (the kind of reordering allowed by TSO).
|
||
|
|
*)
|
||
|
|
|
||
|
|
{}
|
||
|
|
|
||
|
|
P0(spinlock_t *s, spinlock_t *t, int *x, int *y)
|
||
|
|
{
|
||
|
|
int r1;
|
||
|
|
|
||
|
|
spin_lock(s);
|
||
|
|
r1 = READ_ONCE(*x);
|
||
|
|
spin_unlock(s);
|
||
|
|
spin_lock(t);
|
||
|
|
WRITE_ONCE(*y, 1);
|
||
|
|
spin_unlock(t);
|
||
|
|
}
|
||
|
|
|
||
|
|
P1(int *x, int *y)
|
||
|
|
{
|
||
|
|
int r2;
|
||
|
|
|
||
|
|
r2 = smp_load_acquire(y);
|
||
|
|
WRITE_ONCE(*x, 1);
|
||
|
|
}
|
||
|
|
|
||
|
|
exists (0:r1=1 /\ 1:r2=1)
|