FYI, this userspace visible change in behaviour breaks Android.
We rely on being able to add a rule and either have a dup be created
(in which case we'll remove it later) or have it fail with EEXIST (in
which case we won't remove it later).
Returning 0 makes atomically changing a rule difficult.
Please revert.
On Wed, May 8, 2019 at 9:39 AM David Miller <da...@davemloft.net> wrote:
>
> From: Hangbin Liu <liuhang...@gmail.com>
> Date: Tue, 7 May 2019 17:11:18 +0800
>
> > With commit 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to
> > fib_nl_newrule") we now able to check if a rule already exists. But this
> > only works with iproute2. For other tools like libnl, NetworkManager,
> > it still could add duplicate rules with only NLM_F_CREATE flag, like
> >
> > [localhost ~ ]# ip rule
> > 0: from all lookup local
> > 32766: from all lookup main
> > 32767: from all lookup default
> > 100000: from 192.168.7.5 lookup 5
> > 100000: from 192.168.7.5 lookup 5
> >
> > As it doesn't make sense to create two duplicate rules, let's just return
> > 0 if the rule exists.
> >
> > Fixes: 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to fib_nl_newrule")
> > Reported-by: Thomas Haller <thal...@redhat.com>
> > Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
>
> Applied and queued up for -stable, thanks.
