1C MP+polockmbonce+poacquiresilsil 2 3(* 4 * Result: Never 5 * 6 * Do spinlocks combined with smp_mb__after_spinlock() provide order 7 * to outside observers using spin_is_locked() to sense the lock-held 8 * state, ordered by acquire? Note that when the first spin_is_locked() 9 * returns false and the second true, we know that the smp_load_acquire() 10 * executed before the lock was acquired (loosely speaking). 11 *) 12 13{ 14} 15 16P0(spinlock_t *lo, int *x) 17{ 18 spin_lock(lo); 19 smp_mb__after_spinlock(); 20 WRITE_ONCE(*x, 1); 21 spin_unlock(lo); 22} 23 24P1(spinlock_t *lo, int *x) 25{ 26 int r1; 27 int r2; 28 int r3; 29 30 r1 = smp_load_acquire(x); 31 r2 = spin_is_locked(lo); 32 r3 = spin_is_locked(lo); 33} 34 35exists (1:r1=1 /\ 1:r2=0 /\ 1:r3=1) 36