patch 'net/e1000: fix igc Tx descriptor ring wrap' has been queued to stable release 24.11.7

[luca.boccassi at gmail.com]

Hi,

FYI, your patch has been queued to stable release 24.11.7

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 07/05/26. 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/bluca/dpdk-stable

This queued commit can be viewed at:
https://github.com/bluca/dpdk-stable/commit/5dd63890cd65ccaca6080848242d46c253c3e02d

Thanks.

Luca Boccassi

---
>From 5dd63890cd65ccaca6080848242d46c253c3e02d Mon Sep 17 00:00:00 2001
From: Shuzo Ichiyoshi <deadcafe.beef at gmail.com>
Date: Mon, 29 Jun 2026 13:51:14 +0900
Subject: [PATCH] net/e1000: fix igc Tx descriptor ring wrap

[ upstream commit 178d2020a40c6dcd86a7853d186f71a973fe8ed0 ]

igc_xmit_pkts() reserves two extra descriptors for launch time.
It indexed sw_ring[tx_last + 2] without wrapping the descriptor
index first.

If tx_last is one of the last two descriptors in the ring, this
reads past the software ring. Wrap the index before looking up
last_id.

Fixes: 2e79349dcd07 ("net/e1000: fix igc launch time calculation")

Signed-off-by: Shuzo Ichiyoshi <deadcafe.beef at gmail.com>
Reviewed-by: Song Yoong Siang <yoong.siang.song at intel.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
---
 drivers/net/igc/igc_txrx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/igc/igc_txrx.c b/drivers/net/igc/igc_txrx.c
index 44016c3dc6..fe757ea882 100644
--- a/drivers/net/igc/igc_txrx.c
+++ b/drivers/net/igc/igc_txrx.c
@@ -1683,7 +1683,11 @@ igc_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 		 * The "last descriptor" of the previously sent packet, if any,
 		 * which used the last descriptor to allocate.
 		 */
-		tx_end = sw_ring[tx_last].last_id;
+		tx_end = (uint16_t)(tx_last);
+		if (tx_end >= txq->nb_tx_desc)
+			tx_end = (uint16_t)(tx_end - txq->nb_tx_desc);
+
+		tx_end = sw_ring[tx_end].last_id;
 
 		/*
 		 * The next descriptor following that "last descriptor" in the
-- 
2.47.3

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2026-07-03 12:55:48.153881057 +0100
+++ 0038-net-e1000-fix-igc-Tx-descriptor-ring-wrap.patch	2026-07-03 12:55:46.670573982 +0100
@@ -1 +1 @@
-From 178d2020a40c6dcd86a7853d186f71a973fe8ed0 Mon Sep 17 00:00:00 2001
+From 5dd63890cd65ccaca6080848242d46c253c3e02d Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 178d2020a40c6dcd86a7853d186f71a973fe8ed0 ]
+
@@ -15 +16,0 @@
-Cc: stable at dpdk.org
@@ -21 +22 @@
- drivers/net/intel/e1000/igc_txrx.c | 6 +++++-
+ drivers/net/igc/igc_txrx.c | 6 +++++-
@@ -24,5 +25,5 @@
-diff --git a/drivers/net/intel/e1000/igc_txrx.c b/drivers/net/intel/e1000/igc_txrx.c
-index 1ab8f2079d..d61fdb33a8 100644
---- a/drivers/net/intel/e1000/igc_txrx.c
-+++ b/drivers/net/intel/e1000/igc_txrx.c
-@@ -1834,7 +1834,11 @@ igc_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
+diff --git a/drivers/net/igc/igc_txrx.c b/drivers/net/igc/igc_txrx.c
+index 44016c3dc6..fe757ea882 100644
+--- a/drivers/net/igc/igc_txrx.c
++++ b/drivers/net/igc/igc_txrx.c
+@@ -1683,7 +1683,11 @@ igc_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
@@ -32,2 +33,2 @@
--		tx_end = sw_ring[tx_last + 2].last_id;
-+		tx_end = (uint16_t)(tx_last + 2);
+-		tx_end = sw_ring[tx_last].last_id;
++		tx_end = (uint16_t)(tx_last);