[dpdk-stable] patch 'net/ixgbe: 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/f5d573d8ff6cf47e266dbfc6ec8f8ef318b3982b

Thanks.

Kevin Traynor

---
>From f5d573d8ff6cf47e266dbfc6ec8f8ef318b3982b Mon Sep 17 00:00:00 2001
From: Qi Zhang <qi.z.zhang at intel.com>
Date: Sat, 4 May 2019 17:29:39 +0800
Subject: [PATCH] net/ixgbe: fix Tx threshold setup

[ upstream commit 9f5d2352fe45bee575f50f4a7131f3beee52b43f ]

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that an outdated DD status be checked as tx_next_dd, then segment fault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: af75078fece3 ("first public release")

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

diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
index 46c93f595..55740e75b 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx.c
@@ -2497,12 +2497,27 @@ ixgbe_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 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 -(EINVAL);
+	}
 	if (tx_rs_thresh >= (nb_desc - 2)) {
 		PMD_INIT_LOG(ERR, "tx_rs_thresh must be less than the number "
-- 
2.20.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2019-06-21 17:22:12.062753742 +0100
+++ 0006-net-ixgbe-fix-Tx-threshold-setup.patch	2019-06-21 17:22:11.714519330 +0100
@@ -1 +1 @@
-From 9f5d2352fe45bee575f50f4a7131f3beee52b43f Mon Sep 17 00:00:00 2001
+From f5d573d8ff6cf47e266dbfc6ec8f8ef318b3982b Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 9f5d2352fe45bee575f50f4a7131f3beee52b43f ]
+
@@ -17 +18,0 @@
-Cc: stable at dpdk.org
@@ -26 +27 @@
-index 1fbc754ae..3072bc1b5 100644
+index 46c93f595..55740e75b 100644