Re: netlink stats: Ability to get stats for a single device?

[Eric Dumazet <eric.dumazet@gmail.com>]

Le mardi 26 octobre 2010 à 13:29 -0700, Ben Greear a écrit :

> I'm trying to craft my own netlink message...basically:
> 
>     memset(&snl, 0, sizeof(snl));
>     snl.nl_family = AF_NETLINK;
>     snl.nl_pid    = 0;
>     snl.nl_groups = 0;
> 
>     memset(&buffer, 0, sizeof(buffer));
>     nlh->nlmsg_type = msg_type;
>     nlh->nlmsg_flags = NLM_F_MATCH|NLM_F_REQUEST;

dont use F_MATCH : check net/core/rtnetlink.c

vi +1660 net/core/rtnetlink.c

You _dont_ want to call 'dumpit' : so dont use a bit present in
NLM_F_DUMP at all:

        if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {
                struct sock *rtnl;
                rtnl_dumpit_func dumpit;

                dumpit = rtnl_get_dumpit(family, type);
                if (dumpit == NULL)
                        return -EOPNOTSUPP;

                __rtnl_unlock();
                rtnl = net->rtnl;
                err = netlink_dump_start(rtnl, skb, nlh, dumpit, NULL);
                rtnl_lock();
                return err;
        }

You want instead to call the 'doit' handler  (one device only)

        doit = rtnl_get_doit(family, type);
        if (doit == NULL)
                return -EOPNOTSUPP;

        return doit(skb, nlh, (void *)&rta_buf[0]);