Description of problem:
The existing tapset libraries provide probes and functions for common networking subsystems including Sun RPC and NFS. The implementation in systemtap 1.7 only supports the AF_INET (ipv4) address family.

Version-Release number of selected component (if applicable):
systemtap-1.7-*.el6

How reproducible:
100%

Steps to Reproduce:
1. On a system with ipv6 enabled execute a script that will evaluate a tapset variable containing an IP address or that calls a tapset function returning an IP address
  
Actual results:
Address filled as "Unsupported Address Family"

Expected results:
Address filled with valid ipv6 address

Additional info:

I noticed this with the nfsdtop.stp example which evaluates the client_ip tapset variable in a number of probes:

probe nfsd.proc.lookup {
        nfsd_lookups <<< 1
        nfsd_lookup_clients[client_ip] <<< 1
        nfsd_lookup_clients_last_file[client_ip] = filename
}

Using the script on a host with ipv6 clients causes most operations to be attributed to "Unsupported Address Family". This comes from the rpc.stp tapset:

        if (s_addr == 0)
                return "Unsupported Address Family"
        return sprintf("%s:%d", daddr_to_string(s_addr),
                       @cast(addr, "sockaddr_in")->sin_port)

This work has been tracked upstream as PR13646 and systemtap-1.8 will include much better ipv6 support in these tapsets.