From: Dan Carpenter <redacted>
Date: Fri, 28 Apr 2017 16:03:48 +0300

We recently added a check to see if nla_nest_start() fails.  There are
two issues with that.  First, if it fails then I don't think we should
call nla_nest_cancel().  Second, it's slightly convoluted but the
current code returns success but we should return -EMSGSIZE instead.

Fixes: a50fe0ffd76f ("lwtunnel: check return value of nla_nest_start")
Signed-off-by: Dan Carpenter <redacted>

Applied.