patch 'net/mlx5: allow MTU mismatch for running shared queue' has been queued to stable release 24.11.5
luca.boccassi at gmail.com
luca.boccassi at gmail.com
Fri Feb 20 15:56:35 CET 2026
Hi,
FYI, your patch has been queued to stable release 24.11.5
Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 02/22/26. 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/d2d388d23c291daf1dbcf295a3f305012dc6d04f
Thanks.
Luca Boccassi
---
>From d2d388d23c291daf1dbcf295a3f305012dc6d04f Mon Sep 17 00:00:00 2001
From: Shani Peretz <shperetz at nvidia.com>
Date: Thu, 29 Jan 2026 10:13:23 +0200
Subject: [PATCH] net/mlx5: allow MTU mismatch for running shared queue
[ upstream commit aab5fcbd6a79954e311c91ba65f7198e7a73ca24 ]
Previously, mlx5_shared_rxq_match() rejected any MTU mismatch between
a port and the shared RX queue, even when the queue hardware was already
running. This caused failures when hot-adding representors after runtime
MTU changes (new port has default MTU=1500, but running queue was created
with MTU=9000). It also prevented proper port reconfiguration scenarios.
The fix allows MTU mismatches when rxq_ctrl->obj != NULL (queue is
running), since runtime MTU changes via rte_eth_dev_set_mtu() only update
software bookkeeping without recreating hardware resources. Stopped queues
still enforce MTU matching to trigger proper reconfiguration.
This patch also removes the redundant priv->mtu field and uses
dev->data->mtu consistently for MTU tracking throughout the driver.
Fixes: 4414eb800708 ("net/mlx5: store MTU at Rx queue allocation time")
Fixes: 09c2555303be ("net/mlx5: support shared Rx queue")
Signed-off-by: Shani Peretz <shperetz at nvidia.com>
Acked-by: Dariusz Sosnowski <dsosnowski at nvidia.com>
---
drivers/net/mlx5/linux/mlx5_os.c | 6 +--
drivers/net/mlx5/mlx5.h | 1 -
drivers/net/mlx5/mlx5_ethdev.c | 3 --
drivers/net/mlx5/mlx5_rxq.c | 85 ++++++++++++++++++++++++------
drivers/net/mlx5/windows/mlx5_os.c | 6 +--
5 files changed, 72 insertions(+), 29 deletions(-)
diff --git a/drivers/net/mlx5/linux/mlx5_os.c b/drivers/net/mlx5/linux/mlx5_os.c
index 173b2d64f6..d0ce4c9a17 100644
--- a/drivers/net/mlx5/linux/mlx5_os.c
+++ b/drivers/net/mlx5/linux/mlx5_os.c
@@ -1335,7 +1335,6 @@ err_secondary:
priv->sh = sh;
priv->dev_port = spawn->phys_port;
priv->pci_dev = spawn->pci_dev;
- priv->mtu = RTE_ETHER_MTU;
/* Some internal functions rely on Netlink sockets, open them now. */
priv->nl_socket_rdma = nl_rdma;
priv->nl_socket_route = mlx5_nl_init(NETLINK_ROUTE, 0);
@@ -1607,14 +1606,13 @@ err_secondary:
}
#endif
/* Get actual MTU if possible. */
- err = mlx5_get_mtu(eth_dev, &priv->mtu);
+ err = mlx5_get_mtu(eth_dev, ð_dev->data->mtu);
if (err) {
err = rte_errno;
goto error;
}
- eth_dev->data->mtu = priv->mtu;
DRV_LOG(DEBUG, "port %u MTU is %u", eth_dev->data->port_id,
- priv->mtu);
+ eth_dev->data->mtu);
/* Initialize burst functions to prevent crashes before link-up. */
eth_dev->rx_pkt_burst = rte_eth_pkt_burst_dummy;
eth_dev->tx_pkt_burst = rte_eth_pkt_burst_dummy;
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index 39a0705efa..9d97d99d68 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -1961,7 +1961,6 @@ struct mlx5_priv {
uint16_t vlan_filter[MLX5_MAX_VLAN_IDS]; /* VLAN filters table. */
unsigned int vlan_filter_n; /* Number of configured VLAN filters. */
/* Device properties. */
- uint16_t mtu; /* Configured MTU. */
uint16_t min_mtu; /* Minimum MTU allowed on the NIC. */
uint16_t max_mtu; /* Maximum MTU allowed on the NIC. */
unsigned int isolated:1; /* Whether isolated mode is enabled. */
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index c93a7ac4f2..00a1d444ef 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -679,7 +679,6 @@ mlx5_dev_supported_ptypes_get(struct rte_eth_dev *dev, size_t *no_of_elements)
int
mlx5_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
{
- struct mlx5_priv *priv = dev->data->dev_private;
uint16_t kern_mtu = 0;
int ret;
@@ -688,7 +687,6 @@ mlx5_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
return ret;
if (kern_mtu == mtu) {
- priv->mtu = mtu;
DRV_LOG(DEBUG, "port %u adapter MTU was already set to %u",
dev->data->port_id, mtu);
return 0;
@@ -702,7 +700,6 @@ mlx5_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
if (ret)
return ret;
if (kern_mtu == mtu) {
- priv->mtu = mtu;
DRV_LOG(DEBUG, "port %u adapter MTU set to %u",
dev->data->port_id, mtu);
return 0;
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 76fddb262e..eb56618490 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -658,8 +658,6 @@ mlx5_rx_queue_pre_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t *desc,
struct mlx5_rxq_ctrl **rxq_ctrl)
{
struct mlx5_priv *priv = dev->data->dev_private;
- struct mlx5_rxq_priv *rxq;
- bool empty;
if (*desc > mlx5_dev_get_max_wq_size(priv->sh)) {
DRV_LOG(ERR,
@@ -698,14 +696,6 @@ mlx5_rx_queue_pre_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t *desc,
if ((*rxq_ctrl)->obj != NULL)
/* Some port using shared Rx queue has been started. */
return 0;
- /* Release all owner RxQ to reconfigure Shared RxQ. */
- do {
- rxq = LIST_FIRST(&(*rxq_ctrl)->owners);
- LIST_REMOVE(rxq, owner_entry);
- empty = LIST_EMPTY(&(*rxq_ctrl)->owners);
- mlx5_rxq_release(ETH_DEV(rxq->priv), rxq->idx);
- } while (!empty);
- *rxq_ctrl = NULL;
}
return 0;
}
@@ -779,10 +769,21 @@ mlx5_shared_rxq_match(struct mlx5_rxq_ctrl *rxq_ctrl, struct rte_eth_dev *dev,
dev->data->port_id, idx);
return false;
}
- if (priv->mtu != rxq_ctrl->mtu) {
- DRV_LOG(ERR, "port %u queue index %u failed to join shared group: mtu mismatch",
- dev->data->port_id, idx);
- return false;
+ if (dev->data->mtu != rxq_ctrl->mtu) {
+ /*
+ * MTU mismatch is only a problem when the queue hasn't been started yet.
+ * If rxq_ctrl->obj is NULL, the queue hardware objects haven't been created,
+ * meaning we're in the initial configuration phase where MTU must match.
+ * If obj != NULL, the queue is already running with its hardware configured,
+ * and runtime MTU changes are safe as they only update software bookkeeping
+ * without recreating hardware resources.
+ */
+ if (rxq_ctrl->obj == NULL) {
+ DRV_LOG(DEBUG, "port %u queue index %u: mtu mismatch with existing shared rxq_ctrl "
+ "(port mtu=%u rxq_ctrl mtu=%u), reconfiguration needed",
+ dev->data->port_id, idx, dev->data->mtu, rxq_ctrl->mtu);
+ return false;
+ }
}
if (priv->dev_data->dev_conf.intr_conf.rxq !=
spriv->dev_data->dev_conf.intr_conf.rxq) {
@@ -925,8 +926,57 @@ mlx5_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
if (rxq_ctrl != NULL &&
!mlx5_shared_rxq_match(rxq_ctrl, dev, idx, desc, socket,
conf, mp)) {
- rte_errno = EINVAL;
- return -rte_errno;
+ struct mlx5_rxq_priv *rxq_tmp;
+ bool empty;
+
+ /*
+ * Configuration mismatch detected with existing shared RXQ.
+ * We need to reconfigure, but only if it's safe to do so.
+ *
+ * First check: If hardware objects are allocated, the shared queue has
+ * been started. Reconfiguration would require destroying and recreating
+ * hardware resources, which cannot be done while the queue is active.
+ * Return EBUSY to force caller to stop the queue first.
+ */
+ if (rxq_ctrl->obj != NULL) {
+ DRV_LOG(ERR, "port %u queue index %u: cannot reconfigure shared RXQ while started",
+ dev->data->port_id, idx);
+ rte_errno = EBUSY;
+ return -rte_errno;
+ }
+
+ /*
+ * Second check: Even if hardware objects aren't allocated yet,
+ * verify that no owner port is actively using this queue.
+ * refcnt == 1 means the queue exists but is idle (only setup reference).
+ * refcnt > 1 means the queue is being used by flows or other components.
+ * This prevents releasing a queue that other ports depend on.
+ */
+ LIST_FOREACH(rxq_tmp, &rxq_ctrl->owners, owner_entry) {
+ if (rxq_tmp->refcnt > 1) {
+ DRV_LOG(ERR, "port %u queue index %u: cannot reconfigure shared RXQ "
+ "while other ports are running",
+ dev->data->port_id, idx);
+ rte_errno = EBUSY;
+ return -rte_errno;
+ }
+ }
+
+ /*
+ * Safe to reconfigure: hardware not started and no active users.
+ * Release all owner ports from the existing shared rxq_ctrl.
+ * This will decrement references and eventually free the old rxq_ctrl.
+ * Setting rxq_ctrl to NULL triggers creation of a new one below with
+ * the updated configuration.
+ */
+ do {
+ rxq_tmp = LIST_FIRST(&rxq_ctrl->owners);
+ LIST_REMOVE(rxq_tmp, owner_entry);
+ empty = LIST_EMPTY(&rxq_ctrl->owners);
+ mlx5_rxq_release(ETH_DEV(rxq_tmp->priv), rxq_tmp->idx);
+ } while (!empty);
+
+ rxq_ctrl = NULL;
}
} else {
res = mlx5_rx_queue_pre_setup(dev, idx, &desc, &rxq_ctrl);
@@ -1770,7 +1820,8 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
LIST_INIT(&tmpl->owners);
MLX5_ASSERT(n_seg && n_seg <= MLX5_MAX_RXQ_NSEG);
/*
- * Save the original MTU to check against for shared rx queues.
+ * Save the current MTU to check against for shared rx queues.
+ * Use dev->data->mtu which reflects the actual current MTU.
*/
tmpl->mtu = dev->data->mtu;
/*
diff --git a/drivers/net/mlx5/windows/mlx5_os.c b/drivers/net/mlx5/windows/mlx5_os.c
index aba876a075..52ac03014f 100644
--- a/drivers/net/mlx5/windows/mlx5_os.c
+++ b/drivers/net/mlx5/windows/mlx5_os.c
@@ -397,7 +397,6 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
priv->sh = sh;
priv->dev_port = spawn->phys_port;
priv->pci_dev = spawn->pci_dev;
- priv->mtu = RTE_ETHER_MTU;
priv->mp_id.port_id = port_id;
strlcpy(priv->mp_id.name, MLX5_MP_NAME, RTE_MP_MAX_NAME_LEN);
priv->representor = !!switch_info->representor;
@@ -505,14 +504,13 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
}
#endif
/* Get actual MTU if possible. */
- err = mlx5_get_mtu(eth_dev, &priv->mtu);
+ err = mlx5_get_mtu(eth_dev, ð_dev->data->mtu);
if (err) {
err = rte_errno;
goto error;
}
- eth_dev->data->mtu = priv->mtu;
DRV_LOG(DEBUG, "port %u MTU is %u.", eth_dev->data->port_id,
- priv->mtu);
+ eth_dev->data->mtu);
/* Initialize burst functions to prevent crashes before link-up. */
eth_dev->rx_pkt_burst = rte_eth_pkt_burst_dummy;
eth_dev->tx_pkt_burst = rte_eth_pkt_burst_dummy;
--
2.47.3
---
Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- - 2026-02-20 14:55:46.791657147 +0000
+++ 0093-net-mlx5-allow-MTU-mismatch-for-running-shared-queue.patch 2026-02-20 14:55:43.340193380 +0000
@@ -1 +1 @@
-From aab5fcbd6a79954e311c91ba65f7198e7a73ca24 Mon Sep 17 00:00:00 2001
+From d2d388d23c291daf1dbcf295a3f305012dc6d04f Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit aab5fcbd6a79954e311c91ba65f7198e7a73ca24 ]
+
@@ -22 +23,0 @@
-Cc: stable at dpdk.org
@@ -27 +27,0 @@
- doc/guides/nics/mlx5.rst | 7 +++
@@ -33 +33 @@
- 6 files changed, 79 insertions(+), 29 deletions(-)
+ 5 files changed, 72 insertions(+), 29 deletions(-)
@@ -35,18 +34,0 @@
-diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
-index a1c23fbf8b..1c891b432f 100644
---- a/doc/guides/nics/mlx5.rst
-+++ b/doc/guides/nics/mlx5.rst
-@@ -1833,6 +1833,13 @@ Limitations
-
- #. Counters of received packets and bytes of queues in the same group and queue ID are same.
-
-+#. Each Rx queue in share group must have the same queue configuration.
-+
-+#. Ports in share group must have equal MTU at port start time.
-+
-+#. Reconfiguring a shared queue
-+ while it is in use (started or referenced by flow rules) is not allowed.
-+
-
- .. _mlx5_rx_threshold:
-
@@ -54 +36 @@
-index 7624b2aba2..7b21bc4ec2 100644
+index 173b2d64f6..d0ce4c9a17 100644
@@ -57 +39 @@
-@@ -1334,7 +1334,6 @@ err_secondary:
+@@ -1335,7 +1335,6 @@ err_secondary:
@@ -65 +47 @@
-@@ -1606,14 +1605,13 @@ err_secondary:
+@@ -1607,14 +1606,13 @@ err_secondary:
@@ -83 +65 @@
-index d84445db49..cdc61f6b70 100644
+index 39a0705efa..9d97d99d68 100644
@@ -86 +68 @@
-@@ -1984,7 +1984,6 @@ struct mlx5_priv {
+@@ -1961,7 +1961,6 @@ struct mlx5_priv {
@@ -123 +105 @@
-index 9210a92c5f..c4ba746d47 100644
+index 76fddb262e..eb56618490 100644
@@ -126 +108 @@
-@@ -659,8 +659,6 @@ mlx5_rx_queue_pre_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t *desc,
+@@ -658,8 +658,6 @@ mlx5_rx_queue_pre_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t *desc,
@@ -135 +117 @@
-@@ -699,14 +697,6 @@ mlx5_rx_queue_pre_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t *desc,
+@@ -698,14 +696,6 @@ mlx5_rx_queue_pre_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t *desc,
@@ -150 +132 @@
-@@ -780,10 +770,21 @@ mlx5_shared_rxq_match(struct mlx5_rxq_ctrl *rxq_ctrl, struct rte_eth_dev *dev,
+@@ -779,10 +769,21 @@ mlx5_shared_rxq_match(struct mlx5_rxq_ctrl *rxq_ctrl, struct rte_eth_dev *dev,
@@ -176 +158 @@
-@@ -926,8 +927,57 @@ mlx5_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
+@@ -925,8 +926,57 @@ mlx5_rx_queue_setup(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -236 +218 @@
-@@ -1813,7 +1863,8 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
+@@ -1770,7 +1820,8 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
@@ -247 +229 @@
-index 4a00c28009..37a6bdfe9a 100644
+index aba876a075..52ac03014f 100644
@@ -250 +232 @@
-@@ -396,7 +396,6 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
+@@ -397,7 +397,6 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
@@ -258 +240 @@
-@@ -504,14 +503,13 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
+@@ -505,14 +504,13 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
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