int ipc_rcu_getref(void *ptr)
{
	struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;

	return atomic_inc_not_zero(&p->refcount);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.