packet: doc: add documentation for VLAN TPID delivery

Introduce TP_STATUS_VLAN_TPID_VALID bit into the documentation.

Signed-off-by: Atzm Watanabe <atzm@stratosphere.co.jp>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/Documentation/networking/packet_mmap.txt b/Documentation/networking/packet_mmap.txt
index 4288ffafba9f..723bf3d33a6e 100644
--- a/Documentation/networking/packet_mmap.txt
+++ b/Documentation/networking/packet_mmap.txt
@@ -517,8 +517,6 @@ where 'tpacket_version' can be TPACKET_V1 (default), TPACKET_V2, TPACKET_V3.
 TPACKET_V1:
         - Default if not otherwise specified by setsockopt(2)
         - RX_RING, TX_RING available
-        - VLAN metadata information available for packets
-          (TP_STATUS_VLAN_VALID)
 
 TPACKET_V1 --> TPACKET_V2:
         - Made 64 bit clean due to unsigned long usage in TPACKET_V1
@@ -526,6 +524,13 @@ TPACKET_V1 --> TPACKET_V2:
           userspace and the like
         - Timestamp resolution in nanoseconds instead of microseconds
         - RX_RING, TX_RING available
+        - VLAN metadata information available for packets
+          (TP_STATUS_VLAN_VALID, TP_STATUS_VLAN_TPID_VALID),
+          in the tpacket2_hdr structure:
+                - TP_STATUS_VLAN_VALID bit being set into the tp_status field indicates
+                  that the tp_vlan_tci field has valid VLAN TCI value
+                - TP_STATUS_VLAN_TPID_VALID bit being set into the tp_status field
+                  indicates that the tp_vlan_tpid field has valid VLAN TPID value
         - How to switch to TPACKET_V2:
                 1. Replace struct tpacket_hdr by struct tpacket2_hdr
                 2. Query header len and save