Function critical_enter

freebsd/sys/systm.h:282–292

#define critical_exit() critical_exit_KBI()
#else
static __inline void
critical_enter(void)
{
#ifndef FSTACK
	struct thread_lite *td;

	td = (struct thread_lite *)curthread;
	td->td_critnest++;
	atomic_interrupt_fence();
#endif
}

static __inline void
critical_exit(void)