The issue only appeared with hardware-timestamping enabled
(RTE_ETH_RX_OFFLOAD_TIMESTAMP).
The length of the prepended hardware timestamp was not subtracted from
the data length so that received packets were 16 bytes longer than
expected.
In scatter-gather mode only the first mbuf has a timestamp but the
data offset of the follow-up mbufs was not adjusted accordingly.
This caused 16 bytes of packet data to be missing between
the segments.
Signed-off-by: Martin Weiser <martin.wei...@allegro-packets.com>
---
v2:
* Added comments for clarification.
drivers/net/igc/igc_txrx.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/net/igc/igc_txrx.c b/drivers/net/igc/igc_txrx.c
index d0cee1b016..fabab5b1a3 100644
--- a/drivers/net/igc/igc_txrx.c
+++ b/drivers/net/igc/igc_txrx.c
@@ -347,6 +347,13 @@ igc_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
uint16_t nb_pkts)
rxm->data_off = RTE_PKTMBUF_HEADROOM;
data_len = rte_le_to_cpu_16(rxd.wb.upper.length) - rxq->crc_len;
+ /*
+ * When the RTE_ETH_RX_OFFLOAD_TIMESTAMP offload is enabled the
+ * length in the descriptor still accounts for the timestamp so
+ * it must be subtracted.
+ */
+ if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP)
+ data_len -= IGC_TS_HDR_LEN;
rxm->data_len = data_len;
rxm->pkt_len = data_len;
rxm->nb_segs = 1;
@@ -509,6 +516,24 @@ igc_recv_scattered_pkts(void *rx_queue, struct rte_mbuf
**rx_pkts,
*/
rxm->data_off = RTE_PKTMBUF_HEADROOM;
data_len = rte_le_to_cpu_16(rxd.wb.upper.length);
+ if (rxq->offloads & RTE_ETH_RX_OFFLOAD_TIMESTAMP) {
+ /*
+ * When the RTE_ETH_RX_OFFLOAD_TIMESTAMP offload is
enabled
+ * the pkt_addr of all software ring entries is moved
forward
+ * by IGC_TS_HDR_LEN (see igc_alloc_rx_queue_mbufs())
so that
+ * when the hardware writes the packet with a prepended
+ * timestamp the actual packet data still starts at the
+ * normal data offset. The length in the descriptor
still
+ * accounts for the timestamp so it needs to be
subtracted.
+ * Follow-up mbufs do not have the timestamp so the data
+ * offset must be adjusted to point to the start of the
packet
+ * data.
+ */
+ if (first_seg == NULL)
+ data_len -= IGC_TS_HDR_LEN;
+ else
+ rxm->data_off -= IGC_TS_HDR_LEN;
+ }
rxm->data_len = data_len;
/*
@@ -557,6 +582,7 @@ igc_recv_scattered_pkts(void *rx_queue, struct rte_mbuf
**rx_pkts,
last_seg->data_len = last_seg->data_len -
(RTE_ETHER_CRC_LEN - data_len);
last_seg->next = NULL;
+ rxm = last_seg;
} else {
rxm->data_len = (uint16_t)
(data_len - RTE_ETHER_CRC_LEN);
--
2.47.0
