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From:   Matteo Croce <mcroce@redhat.com>
To:     netdev@vger.kernel.org
Cc:     Jay Vosburgh <j.vosburgh@gmail.com>,
        Veaceslav Falico <vfalico@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>,
        "David S . Miller " <davem@davemloft.net>,
        Stanislav Fomichev <sdf@google.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Song Liu <songliubraving@fb.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Paul Blakey <paulb@mellanox.com>, linux-kernel@vger.kernel.org
Subject: [PATCH net-next 1/4] flow_dissector: add meaningful comments
Date:   Mon, 21 Oct 2019 22:09:45 +0200
Message-Id: <20191021200948.23775-2-mcroce@redhat.com>
In-Reply-To: <20191021200948.23775-1-mcroce@redhat.com>
References: <20191021200948.23775-1-mcroce@redhat.com>
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Documents two piece of code which can't be understood at a glance.

Signed-off-by: Matteo Croce <mcroce@redhat.com>
---
 include/net/flow_dissector.h | 1 +
 net/core/flow_dissector.c    | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 90bd210be060..7747af3cc500 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -282,6 +282,7 @@ struct flow_keys {
 =09struct flow_dissector_key_vlan cvlan;
 =09struct flow_dissector_key_keyid keyid;
 =09struct flow_dissector_key_ports ports;
+=09/* 'addrs' must be the last member */
 =09struct flow_dissector_key_addrs addrs;
 };
=20
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 7c09d87d3269..affde70dad47 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1374,6 +1374,9 @@ static inline size_t flow_keys_hash_length(const stru=
ct flow_keys *flow)
 {
 =09size_t diff =3D FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs);
 =09BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32));
+=09/* flow.addrs MUST be the last member in struct flow_keys because
+=09 * different L3 protocols have different address length
+=09 */
 =09BUILD_BUG_ON(offsetof(typeof(*flow), addrs) !=3D
 =09=09     sizeof(*flow) - sizeof(flow->addrs));
=20
@@ -1421,6 +1424,9 @@ __be32 flow_get_u32_dst(const struct flow_keys *flow)
 }
 EXPORT_SYMBOL(flow_get_u32_dst);
=20
+/* Sort the source and destination IP (and the ports if the IP are the sam=
e),
+ * to have consistent hash within the two directions
+ */
 static inline void __flow_hash_consistentify(struct flow_keys *keys)
 {
 =09int addr_diff, i;
--=20
2.21.0