Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 26 Apr 2019 12:51:17 +0200
From:   Jiri Pirko <jiri@resnulli.us>
To:     Michal Kubecek <mkubecek@suse.cz>
Cc:     "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        David Ahern <dsahern@gmail.com>,
        Johannes Berg <johannes.berg@intel.com>,
        Jiri Pirko <jiri@mellanox.com>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>,
        netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 1/3] netlink: make nla_nest_start() add
 NLA_F_NESTED flag
Message-ID: <20190426105117.GA2157@nanopsycho>
References: <cover.1556269635.git.mkubecek@suse.cz>
 <5278b013a953d4fb2e7944fc810f783d70ea52a5.1556269635.git.mkubecek@suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5278b013a953d4fb2e7944fc810f783d70ea52a5.1556269635.git.mkubecek@suse.cz>
User-Agent: Mutt/1.11.3 (2019-02-01)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Fri, Apr 26, 2019 at 11:13:06AM CEST, mkubecek@suse.cz wrote:
>Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
>netlink based interfaces (including recently added ones) are still not
>setting it in kernel generated messages. Without the flag, message parsers
>not aware of attribute semantics (e.g. wireshark dissector or libmnl's
>mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
>the structure of their contents.
>
>Unfortunately we cannot just add the flag everywhere as there may be
>userspace applications which check nlattr::nla_type directly rather than
>through a helper masking out the flags. Therefore the patch renames
>nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
>as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
>are rewritten to use nla_nest_start().
>
>Except for changes in include/net/netlink.h, the patch was generated using
>this semantic patch:
>
>@@ expression E1, E2; @@
>-nla_nest_start(E1, E2)
>+nla_nest_start_noflag(E1, E2)
>
>@@ expression E1, E2; @@
>-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
>+nla_nest_start(E1, E2)
>
>Signed-off-by: Michal Kubecek <mkubecek@suse.cz>

Acked-by: Jiri Pirko <jiri@mellanox.com>