Hi guys,
I have a new link driver that registers a rtnl_link_ops. For many
things, the rtnl interfaces are perfectly suited: I can use netlink in
userspace to check out packet counts, adjust interface parameters, and
all sorts of things. There is even the "fill_info" function exporting
interface-specific types of data to userspace through the standard
netlink interfaces. I'm glad this is here, because it's exactly what I
want.
Problem: sometimes I want to export a *lot* of data to userspace. When
this happens, even if I make the netlink socket receive buffer really
huge, this code path is still reached in rtnetlink.c:
err = rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, 0,
NLM_F_MULTI,
ext_filter_mask);
/* If we ran out of room on the first message,
* we're in trouble
*/
WARN_ON((err == -EMSGSIZE) && (skb->len == 0));
That is -- it tries to fill the skb (for sending it back to
userspace), but doesn't have enough room, so it returns -EMSGSIZE.
That seems like reasonable behavior, but it doesn't really help me
obtain my goal. I'd like to send quite a bit of data back to userspace
for a network interface, and I'd like to do it using the standard
netlink APIs. Is this possible?
Thanks,
Jason
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