netdev - Re: [patch iproute2 v8 1/2] lib/libnetlink: Add functions rtnl_talk_msg and rtnl_talk

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Message-ID: <20180110201245.GR32305@orbyte.nwl.cc>
Date:   Wed, 10 Jan 2018 21:12:45 +0100
From:   Phil Sutter <phil@....cc>
To:     David Ahern <dsahern@...il.com>
Cc:     Chris Mi <chrism@...lanox.com>, netdev@...r.kernel.org,
        gerlitz.or@...il.com, stephen@...workplumber.org,
        marcelo.leitner@...il.com
Subject: Re: [patch iproute2 v8 1/2] lib/libnetlink: Add functions
 rtnl_talk_msg and rtnl_talk_iov

On Wed, Jan 10, 2018 at 12:20:36PM -0700, David Ahern wrote:
[...]
> 2. I am using a batch file with drop filters:
> 
> filter add dev eth2 ingress protocol ip pref 273 flower dst_ip
> 192.168.253.0/16 action drop
> 
> and for each command tc is trying to dlopen m_drop.so:
> 
> open("/usr/lib/tc//m_drop.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such
> file or directory)

[...]

> Can you look at a follow on patch (not part of this set) to cache status
> of dlopen attempts?

IMHO the logic used in get_action_kind() for gact is the culprit here:
After trying to dlopen m_drop.so, it dlopens m_gact.so although it is
present already. (Unless I missed something.)

I guess the better (and easier) fix would be to create some more struct
action_util instances in m_gact.c for the primitives it supports so that
the lookup in action_list succeeds for consecutive uses. Note that
parse_gact() even supports this already.

Cheers, Phil