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net/i40e: fix Tx threshold setup

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Tx desc's DD status is not cleaned by NIC automatically after packets
have been transmitted until software refill a new packet during next
loop. So when tx_free_thresh + tx_rs_thresh > nb_desc, it is possible
that an outdated DD status be checked as tx_next_dd, then segment fault
happen due to free a NULL mbuf pointer.

Then patch fixes this issue by
1. try to adapt tx_rs_thresh to an aggressive tx_free_thresh.
2. queue setup fail when tx_free_thresh + tx_rs_thresh > nb_desc

Fixes: 4861cde46116 ("i40e: new poll mode driver")
Cc: stable@dpdk.org

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Beilei Xing <beilei.xing@intel.com>
This commit is contained in:
Qi Zhang 2019-05-04 17:29:37 +08:00 committed by Ferruh Yigit
parent 1d7be86e38
commit 1c5c7c91d3
1 changed files with 17 additions and 2 deletions
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19
drivers/net/i40e/i40e_rxtx.c
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@ -2169,15 +2169,30 @@ i40e_dev_tx_queue_setup(struct rte_eth_dev *dev,
* - tx_rs_thresh must be a divisor of the ring size.
* - tx_free_thresh must be greater than 0.
* - tx_free_thresh must be less than the size of the ring minus 3.
* - tx_free_thresh + tx_rs_thresh must not exceed nb_desc.
*
* One descriptor in the TX ring is used as a sentinel to avoid a H/W
* race condition, hence the maximum threshold constraints. When set
* to zero use default values.
*/
tx_rs_thresh = (uint16_t)((tx_conf->tx_rs_thresh) ?
tx_conf->tx_rs_thresh : DEFAULT_TX_RS_THRESH);
tx_free_thresh = (uint16_t)((tx_conf->tx_free_thresh) ?
tx_conf->tx_free_thresh : DEFAULT_TX_FREE_THRESH);
/* force tx_rs_thresh to adapt an aggresive tx_free_thresh */
tx_rs_thresh = (DEFAULT_TX_RS_THRESH + tx_free_thresh > nb_desc) ?
nb_desc - tx_free_thresh : DEFAULT_TX_RS_THRESH;
if (tx_conf->tx_rs_thresh > 0)
tx_rs_thresh = tx_conf->tx_rs_thresh;
if (tx_rs_thresh + tx_free_thresh > nb_desc) {
PMD_INIT_LOG(ERR, "tx_rs_thresh + tx_free_thresh must not "
"exceed nb_desc. (tx_rs_thresh=%u "
"tx_free_thresh=%u nb_desc=%u port=%d queue=%d)",
(unsigned int)tx_rs_thresh,
(unsigned int)tx_free_thresh,
(unsigned int)nb_desc,
(int)dev->data->port_id,
(int)queue_idx);
return I40E_ERR_PARAM;
}
if (tx_rs_thresh >= (nb_desc - 2)) {
PMD_INIT_LOG(ERR, "tx_rs_thresh must be less than the "
"number of TX descriptors minus 2. "