Re: [RFC net-next iproute2 1/2] libnetlink: Add test for error code returned from netlink reply

[Cyrill Gorcunov <gorcunov@gmail.com>]

On Thu, Oct 27, 2016 at 09:52:53AM +0300, Cyrill Gorcunov wrote:
...
> > 
> > This looks like a mistake in how you implemented the functionality in the kernel.
> > Despite what it looks like, all netlink request/reply functionality reports
> > errors in current implementation by returning error to the sendmsg request.
> > 
> > What you added implies that the new kernel api is wrong, or many other usages
> > are wrong.  Please fix the kernel.
> 
> No. This is not my code. This code has been in kernel for the really long time.
> I don't know why you've not been doing such test in libnetlink before.
> 
> Actually I've hit this problem accidentaly -- I made a patch 2 from this
> set and run it on the machine where kernel was unpatched, ie without
> raw-diag module, and I found that we can't figure out if kernel notified
> us that some diag module simply not present in the system. And here is
> the only way to find it out.

Also, drop this series for a while, I'll resend new one: the status of
diag should not be tested unconditionally with NLMSG_DONE because the
rtnl_dump_filter_l helper is used not only for diag talks but overall
the iproute2, thus I need to test for status only for specified requests.
And I need to narrow down why not all device bound interfaces are killed
in one pass.

	Cyrill