On Thu, Apr 01, 2021 at 11:52:40AM +0200, David Marchand wrote:
> Tx offload flags are of the application responsibility.
> Leave the mbuf alone and check for TSO where needed.
>
> Signed-off-by: David Marchand <david.march...@redhat.com>
Maybe the problem being solved should be better described in the commit
log. Is it a problem (other than cosmetic) to touch a mbuf in the Tx
function of a driver, where we could expect that the mbuf is owned by
the driver?
The only problem I can think about is in case we transmit a direct mbuf
whose refcnt is increased, but I wonder how much this is really
supported: for instance, several drivers add vlans using
rte_vlan_insert() in their Tx path.
> ---
> drivers/net/tap/rte_eth_tap.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index c36d4bf76e..285fe395c5 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -562,6 +562,7 @@ tap_tx_l3_cksum(char *packet, uint64_t ol_flags, unsigned
> int l2_len,
> uint16_t *l4_phdr_cksum, uint32_t *l4_raw_cksum)
> {
> void *l3_hdr = packet + l2_len;
> + uint64_t csum_l4;
>
> if (ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_IPV4)) {
> struct rte_ipv4_hdr *iph = l3_hdr;
> @@ -571,13 +572,17 @@ tap_tx_l3_cksum(char *packet, uint64_t ol_flags,
> unsigned int l2_len,
> cksum = rte_raw_cksum(iph, l3_len);
> iph->hdr_checksum = (cksum == 0xffff) ? cksum : ~cksum;
> }
> - if (ol_flags & PKT_TX_L4_MASK) {
> +
> + csum_l4 = ol_flags & PKT_TX_L4_MASK;
> + if (ol_flags & PKT_TX_TCP_SEG)
> + csum_l4 |= PKT_TX_TCP_CKSUM;
> + if (csum_l4) {
> void *l4_hdr;
>
> l4_hdr = packet + l2_len + l3_len;
> - if ((ol_flags & PKT_TX_L4_MASK) == PKT_TX_UDP_CKSUM)
> + if (csum_l4 == PKT_TX_UDP_CKSUM)
> *l4_cksum = &((struct rte_udp_hdr
> *)l4_hdr)->dgram_cksum;
> - else if ((ol_flags & PKT_TX_L4_MASK) == PKT_TX_TCP_CKSUM)
> + else if (csum_l4 == PKT_TX_TCP_CKSUM)
> *l4_cksum = &((struct rte_tcp_hdr *)l4_hdr)->cksum;
> else
> return;
> @@ -648,7 +653,8 @@ tap_write_mbufs(struct tx_queue *txq, uint16_t num_mbufs,
> if (txq->csum &&
> ((mbuf->ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_IPV4) ||
> (mbuf->ol_flags & PKT_TX_L4_MASK) == PKT_TX_UDP_CKSUM ||
> - (mbuf->ol_flags & PKT_TX_L4_MASK) == PKT_TX_TCP_CKSUM))) {
> + (mbuf->ol_flags & PKT_TX_L4_MASK) == PKT_TX_TCP_CKSUM) ||
> + (mbuf->ol_flags & PKT_TX_TCP_SEG))) {
> is_cksum = 1;
>
> /* Support only packets with at least layer 4
> @@ -742,9 +748,6 @@ pmd_tx_burst(void *queue, struct rte_mbuf **bufs,
> uint16_t nb_pkts)
> if (tso) {
> struct rte_gso_ctx *gso_ctx = &txq->gso_ctx;
>
> - /* TCP segmentation implies TCP checksum offload */
> - mbuf_in->ol_flags |= PKT_TX_TCP_CKSUM;
> -
> /* gso size is calculated without RTE_ETHER_CRC_LEN */
> hdrs_len = mbuf_in->l2_len + mbuf_in->l3_len +
> mbuf_in->l4_len;
> --
> 2.23.0
>
