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C RM-fixed
(*
* Result: Never
*
* This litmus test demonstrates that the old "roach motel" approach
* to locking, where code can be freely moved into critical sections,
* cannot be used in the Linux kernel.
*)
{
int x;
atomic_t y;
}
P0(int *x, atomic_t *y, spinlock_t *lck)
{
int r2;
spin_lock(lck);
r2 = atomic_inc_return(y);
WRITE_ONCE(*x, 1);
spin_unlock(lck);
}
P1(int *x, atomic_t *y, spinlock_t *lck)
{
int r0;
int r1;
int r2;
r0 = READ_ONCE(*x);
r1 = READ_ONCE(*x);
spin_lock(lck);
r2 = atomic_inc_return(y);
spin_unlock(lck);
}
locations [x;0:r2;1:r0;1:r1;1:r2]
filter (1:r0=0 /\ 1:r1=1)
exists (1:r2=1)
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