xfrm4_protocol_register
int xfrm4_protocol_register(struct xfrm4_protocol *handler, unsigned char protocol);
if (xfrm4_protocol_register(&ah4_protocol, IPPROTO_AH) < 0) {
if (xfrm4_protocol_register(&esp4_protocol, IPPROTO_ESP) < 0) {
err = xfrm4_protocol_register(&vti_esp4_protocol, IPPROTO_ESP);
err = xfrm4_protocol_register(&vti_ah4_protocol, IPPROTO_AH);
err = xfrm4_protocol_register(&vti_ipcomp4_protocol, IPPROTO_COMP);
if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
EXPORT_SYMBOL(xfrm4_protocol_register);
err = xfrm4_protocol_register(&xfrmi_esp4_protocol, IPPROTO_ESP);
err = xfrm4_protocol_register(&xfrmi_ah4_protocol, IPPROTO_AH);
err = xfrm4_protocol_register(&xfrmi_ipcomp4_protocol, IPPROTO_COMP);