34 lines
681 B
Plaintext
34 lines
681 B
Plaintext
C MP+polockonce+poacquiresilsil
|
|
|
|
(*
|
|
* Result: Sometimes
|
|
*
|
|
* Do spinlocks provide order to outside observers using spin_is_locked()
|
|
* to sense the lock-held state, ordered by acquire? Note that when the
|
|
* first spin_is_locked() returns false and the second true, we know that
|
|
* the smp_load_acquire() executed before the lock was acquired (loosely
|
|
* speaking).
|
|
*)
|
|
|
|
{}
|
|
|
|
P0(spinlock_t *lo, int *x) // Producer
|
|
{
|
|
spin_lock(lo);
|
|
WRITE_ONCE(*x, 1);
|
|
spin_unlock(lo);
|
|
}
|
|
|
|
P1(spinlock_t *lo, int *x) // Consumer
|
|
{
|
|
int r1;
|
|
int r2;
|
|
int r3;
|
|
|
|
r1 = smp_load_acquire(x);
|
|
r2 = spin_is_locked(lo);
|
|
r3 = spin_is_locked(lo);
|
|
}
|
|
|
|
exists (1:r1=1 /\ 1:r2=0 /\ 1:r3=1) (* Bad outcome. *)
|