The commit f2a4d086ed4c ("openvswitch: Add packet truncation support.") introduces packet truncation before sending to userspace upcall receiver. This patch passes up the skb->len before truncation so that the upcall receiver knows the original packet size. Potentially this will be used by sFlow, where OVS translates sFlow config header=N to a sample action, truncating packet to N byte in kernel datapath. Thus, only N bytes instead of full-packet size is copied from kernel to userspace, saving the kernel-to-userspace bandwidth.
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| @@ -166,6 +166,7 @@ enum ovs_packet_cmd { · 165 unmodified lines | |||
| 166 | * output port is actually a tunnel port. Contains the output tunnel key | 166 | * output port is actually a tunnel port. Contains the output tunnel key |
| 167 | * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes. | 167 | * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes. |
| 168 | * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and | 168 | * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and |
| 169 | * @OVS_PACKET_ATTR_LEN: Packet size before truncation. | ||
| 169 | * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment | 170 | * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment |
| 170 | * size. | 171 | * size. |
| 171 | * | 172 | * |
| @@ -185,6 +186,7 @@ enum ovs_packet_attr { · 13 unmodified lines | |||
| 185 | OVS_PACKET_ATTR_PROBE, /* Packet operation is a feature probe, | 186 | OVS_PACKET_ATTR_PROBE, /* Packet operation is a feature probe, |
| 186 | error logging should be suppressed. */ | 187 | error logging should be suppressed. */ |
| 187 | OVS_PACKET_ATTR_MRU, /* Maximum received IP fragment size. */ | 188 | OVS_PACKET_ATTR_MRU, /* Maximum received IP fragment size. */ |
| 189 | OVS_PACKET_ATTR_LEN, /* Packet size before truncation. */ | ||
| 188 | __OVS_PACKET_ATTR_MAX | 190 | __OVS_PACKET_ATTR_MAX |
| 189 | }; | 191 | }; |
| 190 | 192 | ||