Hi
> -----Original Message-----
> From: Zhang, AlvinX <alvinx.zh...@intel.com>
> Sent: Thursday, September 2, 2021 16:20
> To: Li, Xiaoyun <xiaoyun...@intel.com>; Ananyev, Konstantin
> <konstantin.anan...@intel.com>
> Cc: dev@dpdk.org; Zhang, AlvinX <alvinx.zh...@intel.com>; sta...@dpdk.org
> Subject: [PATCH] app/testpmd: fix random number of Tx segments
>
> When random number of segments in Tx packets is enabled, the total data space
> length of all segments must be greater or equal than the size of an
> Eth/IP/UDP/timestamp packet, that's total 14 + 20 + 8 + 16 bytes. Otherwise
> the
> Tx engine may cause the application to crash.
>
> Bugzilla ID: 797
> Fixes: 79bec05b32b7 ("app/testpmd: add ability to split outgoing packets")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Alvin Zhang <alvinx.zh...@intel.com>
> ---
> app/test-pmd/config.c | 16 +++++++++++----- app/test-pmd/testpmd.c | 5
> +++++ app/test-pmd/testpmd.h | 5 +++++ app/test-pmd/txonly.c | 7 +++++--
> 4 files changed, 26 insertions(+), 7 deletions(-)
>
> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c index
> 31d8ba1..5105b3b 100644
> --- a/app/test-pmd/config.c
> +++ b/app/test-pmd/config.c
> @@ -3837,10 +3837,11 @@ struct igb_ring_desc_16_bytes {
> * Check that each segment length is greater or equal than
> * the mbuf data size.
> * Check also that the total packet length is greater or equal than the
> - * size of an empty UDP/IP packet (sizeof(struct rte_ether_hdr) +
> - * 20 + 8).
> + * size of an Eth/IP/UDP + timestamp packet
> + * (sizeof(struct rte_ether_hdr) + 20 + 8 + 16).
I don't really agree on this. Most of the time, txonly generate packets with
Eth/IP/UDP. It's not fair to limit the hdr length to include timestamp in all
cases.
And to be honest, I don't see why you need to add "tx_pkt_nb_min_segs". It's
only used in txonly when "TX_PKT_SPLIT_RND". So this issue is because when
"TX_PKT_SPLIT_RND", the random nb_segs is not enough for the hdr.
But if you read txonly carefully, if "TX_PKT_SPLIT_RND", the first segment
length should be equal or greater than 42 (14+20+8). Because when
"TX_PKT_SPLIT_RND", update_pkt_header() should be called. And that function
doesn't deal with header in multi-segments.
I think there's bug here.
So I think you should only add a check in pkt_burst_prepare() in txonly().
if (unlikely(tx_pkt_split == TX_PKT_SPLIT_RND) || txonly_multi_flow)
+ if (tx_pkt_seg_lengths[0] < 42) {
+ err_log;
+ return false;
+ }
update_pkt_header(pkt, pkt_len);
As for timestamp, maybe refer to "pkt_copy_split" in csumonly.c is better? Copy
the extra to the last segment if it's not enough. Not sure how to deal with
this issue better.
> */
> tx_pkt_len = 0;
> + tx_pkt_nb_min_segs = 0;
> for (i = 0; i < nb_segs; i++) {
> if (seg_lengths[i] > mbuf_data_size[0]) {
> fprintf(stderr,
> @@ -3849,11 +3850,16 @@ struct igb_ring_desc_16_bytes {
> return;
> }
> tx_pkt_len = (uint16_t)(tx_pkt_len + seg_lengths[i]);
> +
> + if (!tx_pkt_nb_min_segs &&
> + tx_pkt_len >= (sizeof(struct rte_ether_hdr) + 20 + 8 + 16))
> + tx_pkt_nb_min_segs = i + 1;
> }
> - if (tx_pkt_len < (sizeof(struct rte_ether_hdr) + 20 + 8)) {
> +
> + if (!tx_pkt_nb_min_segs) {
> fprintf(stderr, "total packet length=%u < %d - give up\n",
> - (unsigned) tx_pkt_len,
> - (int)(sizeof(struct rte_ether_hdr) + 20 + 8));
> + (unsigned int) tx_pkt_len,
> + (int)(sizeof(struct rte_ether_hdr) + 20 + 8 + 16));
> return;
> }
>
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c index
> 6cbe9ba..c496e59 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -232,6 +232,11 @@ struct fwd_engine * fwd_engines[] = { }; uint8_t
> tx_pkt_nb_segs = 1; /**< Number of segments in TXONLY packets */
>
> +/**< Minimum number of segments in TXONLY packets to accommodate all
> +packet
> + * headers.
> + */
> +uint8_t tx_pkt_nb_min_segs = 1;
> +
> enum tx_pkt_split tx_pkt_split = TX_PKT_SPLIT_OFF; /**< Split policy for
> packets to TX. */
>
> diff --git a/app/test-pmd/testpmd.h b/app/test-pmd/testpmd.h index
> 16a3598..f5bc427 100644
> --- a/app/test-pmd/testpmd.h
> +++ b/app/test-pmd/testpmd.h
> @@ -464,6 +464,11 @@ enum dcb_mode_enable extern uint16_t
> tx_pkt_length; /**< Length of TXONLY packet */ extern uint16_t
> tx_pkt_seg_lengths[RTE_MAX_SEGS_PER_PKT]; /**< Seg. lengths */ extern
> uint8_t tx_pkt_nb_segs; /**< Number of segments in TX packets */
> +
> +/**< Minimum number of segments in TXONLY packets to accommodate all
> +packet
> + * headers.
> + */
> +extern uint8_t tx_pkt_nb_min_segs;
> extern uint32_t tx_pkt_times_intra;
> extern uint32_t tx_pkt_times_inter;
>
> diff --git a/app/test-pmd/txonly.c b/app/test-pmd/txonly.c index
> aed820f..27e4458 100644
> --- a/app/test-pmd/txonly.c
> +++ b/app/test-pmd/txonly.c
> @@ -195,8 +195,11 @@
> uint32_t nb_segs, pkt_len;
> uint8_t i;
>
> - if (unlikely(tx_pkt_split == TX_PKT_SPLIT_RND))
> - nb_segs = rte_rand() % tx_pkt_nb_segs + 1;
> + if (unlikely(tx_pkt_split == TX_PKT_SPLIT_RND) &&
> + tx_pkt_nb_segs > tx_pkt_nb_min_segs)
> + nb_segs = rte_rand() %
> + (tx_pkt_nb_segs - tx_pkt_nb_min_segs + 1) +
> + tx_pkt_nb_min_segs;
> else
> nb_segs = tx_pkt_nb_segs;
>
> --
> 1.8.3.1
