netdev - Re: iproute2: no error message when link up command fails.

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Date:	Thu, 17 Jul 2008 06:31:54 -0400
From:	jamal <hadi@...erus.ca>
To:	Andreas Henriksson <andreas@...al.se>
Cc:	Stephen Hemminger <shemminger@...tta.com>,
	Johannes Berg <johannes@...solutions.net>,
	489340@...s.debian.org, netdev@...r.kernel.org
Subject: Re: iproute2: no error message when link up command fails.

On Thu, 2008-17-07 at 02:31 +0200, Andreas Henriksson wrote:

> Why? 

Thats just how it rolls.

> This seems like a really bad idea to me, and none of the callers in
> iproute benefits from this as far as I can see.

The receiver(kernel in this case, but it could be some other user space
user) returning a zero means success. Essentially zero is an (Positive)
ACK.
The receiver returning a non-zero implies a failure. Essentially a
N(egative) ACK. 

In the case of a NACK, the kernel must return you the original message
header you sent (similar to the way some icmp messages behave).
The returned error code is a standard errno - if you sent a bad config
you may get an EINVAL back. The sender combines the errno + the header
to figure out what went wrong.

Does that make sense? So the kernel fix is required (as Stephen noted).

cheers,
jamal

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