where timer expiry check is happening before sending ICMP_REPLY in ipv6

Dear all,
In kernel-3.0.26 code net/ipv6/icmp.c, while sending ICMP reply where it checks for the timer expiry. It should check the value given by a router advertisement. I think the expiry value is stored in
rt->rt6_expires in ndisc.c (line no: 1284). Then while sending an ICMP reply, it should check with the expiry timer right? Where that check is happening? Please somebody explain me.

Thank you. 

--Regards,
K.Balakumaran