__asm__ __volatile__()

in include/asm/futex.h [13:61]

• 44 lines of code
• 8 McCabe index (conditional complexity)

	__asm__ __volatile__(					\
		__ASM_SMP_MB					\
	"1:	ldl_l	%0,0(%2)\n"				\
		insn						\
	"2:	stl_c	%1,0(%2)\n"				\
	"	beq	%1,4f\n"				\
	"	mov	$31,%1\n"				\
	"3:	.subsection 2\n"				\
	"4:	br	1b\n"					\
	"	.previous\n"					\
	EXC(1b,3b,$31,%1)					\
	EXC(2b,3b,$31,%1)					\
	:	"=&r" (oldval), "=&r"(ret)			\
	:	"r" (uaddr), "r"(oparg)				\
	:	"memory")

static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
		u32 __user *uaddr)
{
	int oldval = 0, ret;

	if (!access_ok(uaddr, sizeof(u32)))
		return -EFAULT;

	switch (op) {
	case FUTEX_OP_SET:
		__futex_atomic_op("mov %3,%1\n", ret, oldval, uaddr, oparg);
		break;
	case FUTEX_OP_ADD:
		__futex_atomic_op("addl %0,%3,%1\n", ret, oldval, uaddr, oparg);
		break;
	case FUTEX_OP_OR:
		__futex_atomic_op("or %0,%3,%1\n", ret, oldval, uaddr, oparg);
		break;
	case FUTEX_OP_ANDN:
		__futex_atomic_op("andnot %0,%3,%1\n", ret, oldval, uaddr, oparg);
		break;
	case FUTEX_OP_XOR:
		__futex_atomic_op("xor %0,%3,%1\n", ret, oldval, uaddr, oparg);
		break;
	default:
		ret = -ENOSYS;
	}

	if (!ret)
		*oval = oldval;

	return ret;
}