DPDK  20.11.0
Data Structures | Macros | Functions
rte_gso.h File Reference
#include <stdint.h>
#include <rte_mbuf.h>

Go to the source code of this file.

Data Structures

struct  rte_gso_ctx
 

Macros

#define RTE_GSO_FLAG_IPID_FIXED   (1ULL << 0)
 

Functions

int rte_gso_segment (struct rte_mbuf *pkt, const struct rte_gso_ctx *ctx, struct rte_mbuf **pkts_out, uint16_t nb_pkts_out)
 

Detailed Description

Interface to GSO library

Definition in file rte_gso.h.

Macro Definition Documentation

#define RTE_GSO_FLAG_IPID_FIXED   (1ULL << 0)

Use fixed IP ids for output GSO segments. Setting 0 indicates using incremental IP ids.

Definition at line 29 of file rte_gso.h.

Function Documentation

int rte_gso_segment ( struct rte_mbuf pkt,
const struct rte_gso_ctx ctx,
struct rte_mbuf **  pkts_out,
uint16_t  nb_pkts_out 
)

Segmentation function, which supports processing of both single- and multi- MBUF packets.

Note that we refer to the packets that are segmented from the input packet as 'GSO segments'. rte_gso_segment() doesn't check if the input packet has correct checksums, and doesn't update checksums for output GSO segments. Additionally, it doesn't process IP fragment packets.

Before calling rte_gso_segment(), applications must set proper ol_flags for the packet. The GSO library uses the same macros as that of TSO. For example, set PKT_TX_TCP_SEG and PKT_TX_IPV4 in ol_flags to segment a TCP/IPv4 packet. If rte_gso_segment() succeeds, the PKT_TX_TCP_SEG flag is removed for all GSO segments and the input packet.

Each of the newly-created GSO segments is organized as a two-segment MBUF, where the first segment is a standard MBUF, which stores a copy of packet header, and the second is an indirect MBUF which points to a section of data in the input packet. Since each GSO segment has multiple MBUFs (i.e. typically 2 MBUFs), the driver of the interface which the GSO segments are sent to should support transmission of multi-segment packets.

If the input packet is GSO'd, all the indirect segments are attached to the input packet.

rte_gso_segment() will not free the input packet no matter whether it is GSO'd or not, the application should free it after calling rte_gso_segment().

If the memory space in pkts_out or MBUF pools is insufficient, this function fails, and it returns (-1) * errno. Otherwise, GSO succeeds, and this function returns the number of output GSO segments filled in pkts_out.

Parameters
pktThe packet mbuf to segment.
ctxGSO context object pointer.
pkts_outPointer array used to store the MBUF addresses of output GSO segments, when rte_gso_segment() succeeds.
nb_pkts_outThe max number of items that pkts_out can keep.
Returns
  • The number of GSO segments filled in pkts_out on success.
  • Return 0 if it does not need to be GSO'd.
  • Return -ENOMEM if run out of memory in MBUF pools.
  • Return -EINVAL for invalid parameters.