[dpdk-stable] patch 'net/i40e: fix Tx threshold setup' has been queued to LTS release 18.11.3

[Kevin Traynor]

Hi,

FYI, your patch has been queued to LTS release 18.11.3

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 06/26/19. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable-queue/commit/0c474dcc867cbf56f157ba3361b2ed821bd288dd

Thanks.

Kevin Traynor

---
>From 0c474dcc867cbf56f157ba3361b2ed821bd288dd Mon Sep 17 00:00:00 2001
From: Qi Zhang <qi.z.zhang at intel.com>
Date: Sat, 4 May 2019 17:29:37 +0800
Subject: [PATCH] net/i40e: fix Tx threshold setup

[ upstream commit 1c5c7c91d300355b5b76c5c396e54f6b35bac28a ]

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that an outdated DD status be checked as tx_next_dd, then segment fault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")

Signed-off-by: Qi Zhang <qi.z.zhang at intel.com>
Acked-by: Beilei Xing <beilei.xing at intel.com>
---
 drivers/net/i40e/i40e_rxtx.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
index 1489552da..4640a9c66 100644
--- a/drivers/net/i40e/i40e_rxtx.c
+++ b/drivers/net/i40e/i40e_rxtx.c
@@ -2170,4 +2170,5 @@ i40e_dev_tx_queue_setup(struct rte_eth_dev *dev,
 	 *  - 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
@@ -2175,8 +2176,22 @@ i40e_dev_tx_queue_setup(struct rte_eth_dev *dev,
 	 * 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 "
-- 
2.20.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2019-06-21 17:22:12.010854731 +0100
+++ 0005-net-i40e-fix-Tx-threshold-setup.patch	2019-06-21 17:22:11.710519421 +0100
@@ -1 +1 @@
-From 1c5c7c91d300355b5b76c5c396e54f6b35bac28a Mon Sep 17 00:00:00 2001
+From 0c474dcc867cbf56f157ba3361b2ed821bd288dd Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 1c5c7c91d300355b5b76c5c396e54f6b35bac28a ]
+
@@ -17 +18,0 @@
-Cc: stable at dpdk.org