When we pass a qcfg to a driver, make sure it supports the set
parameters by checking it against ->supported_ring_params.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 net/core/dev.h             |  3 +++
 net/core/netdev_config.c   | 26 ++++++++++++++++++++++++++
 net/core/netdev_rx_queue.c |  8 +++-----
 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.h b/net/core/dev.h
index c1cc54e38fe4..c53b8045d685 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -103,6 +103,9 @@ int netdev_queue_config_revalidate(struct net_device *dev,
 				   struct netlink_ext_ack *extack);
 void netdev_queue_config_update_cnt(struct net_device *dev, unsigned int txq,
 				    unsigned int rxq);
+int netdev_queue_config_validate(struct net_device *dev, int rxq_idx,
+				  struct netdev_queue_config *qcfg,
+				  struct netlink_ext_ack *extack);
 
 /* netdev management, shared between various uAPI entry points */
 struct netdev_name_node {
diff --git a/net/core/netdev_config.c b/net/core/netdev_config.c
index 2c9b06f94e01..ffe997893cd1 100644
--- a/net/core/netdev_config.c
+++ b/net/core/netdev_config.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
 #include <linux/netdevice.h>
+#include <linux/ethtool.h>
 #include <net/netdev_queues.h>
 #include <net/netdev_rx_queue.h>
 
@@ -136,6 +137,31 @@ void netdev_queue_config(struct net_device *dev, int rxq,
 }
 EXPORT_SYMBOL(netdev_queue_config);
 
+int netdev_queue_config_validate(struct net_device *dev, int rxq_idx,
+				  struct netdev_queue_config *qcfg,
+				  struct netlink_ext_ack *extack)
+{
+	const struct netdev_queue_mgmt_ops *qops = dev->queue_mgmt_ops;
+	int err;
+
+	if (WARN_ON_ONCE(!qops))
+		return -EINVAL;
+
+	if (!(qops->supported_ring_params & ETHTOOL_RING_USE_RX_BUF_LEN) &&
+	    qcfg->rx_buf_len &&
+	    qcfg->rx_buf_len != dev->cfg_pending->rx_buf_len) {
+		NL_SET_ERR_MSG_MOD(extack, "changing rx-buf-len not supported");
+		return -EINVAL;
+	}
+
+	if (qops->ndo_queue_cfg_validate) {
+		err = qops->ndo_queue_cfg_validate(dev, rxq_idx, qcfg, extack);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
 int netdev_queue_config_revalidate(struct net_device *dev,
 				   struct netlink_ext_ack *extack)
 {
diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index 39834b196e95..d583a9ead9c4 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -37,11 +37,9 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx,
 
 	netdev_queue_config(dev, rxq_idx, &qcfg);
 
-	if (qops->ndo_queue_cfg_validate) {
-		err = qops->ndo_queue_cfg_validate(dev, rxq_idx, &qcfg, extack);
-		if (err)
-			goto err_free_old_mem;
-	}
+	err = netdev_queue_config_validate(dev, rxq_idx, &qcfg, extack);
+	if (err)
+		goto err_free_old_mem;
 
 	err = qops->ndo_queue_mem_alloc(dev, &qcfg, new_mem, rxq_idx);
 	if (err)
-- 
2.49.0