net: introduce a trivial netdev_queue_config()

We may choose to extend or reimplement the logic which renders
the per-queue config. The drivers should not poke directly into
the queue state. Add a helper for drivers to use when they want
to query the config for a specific queue.

Link: https://patch.msgid.link/20260122005113.2476634-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 39 insertions, 3 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 0b95100a7c36..d57e833ce690 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -4326,12 +4326,12 @@ static void bnxt_init_ring_struct(struct bnxt *bp)
 
 	for (i = 0; i < bp->cp_nr_rings; i++) {
 		struct bnxt_napi *bnapi = bp->bnapi[i];
+		struct netdev_queue_config qcfg;
 		struct bnxt_ring_mem_info *rmem;
 		struct bnxt_cp_ring_info *cpr;
 		struct bnxt_rx_ring_info *rxr;
 		struct bnxt_tx_ring_info *txr;
 		struct bnxt_ring_struct *ring;
-		struct netdev_rx_queue *rxq;
 
 		if (!bnapi)
 			continue;
@@ -4349,8 +4349,8 @@ static void bnxt_init_ring_struct(struct bnxt *bp)
 		if (!rxr)
 			goto skip_rx;
 
-		rxq = __netif_get_rx_queue(bp->dev, i);
-		rxr->rx_page_size = rxq->qcfg.rx_page_size;
+		netdev_queue_config(bp->dev, i, &qcfg);
+		rxr->rx_page_size = qcfg.rx_page_size;
 
 		ring = &rxr->rx_ring_struct;
 		rmem = &ring->ring_mem;
diff --git a/include/net/netdev_queues.h b/include/net/netdev_queues.h
index 2ab3eae8e8c3..725bf69ef86c 100644
--- a/include/net/netdev_queues.h
+++ b/include/net/netdev_queues.h
@@ -170,6 +170,9 @@ struct netdev_queue_mgmt_ops {
 	unsigned int supported_params;
 };
 
+void netdev_queue_config(struct net_device *dev, int rxq,
+			 struct netdev_queue_config *qcfg);
+
 bool netif_rxq_has_unreadable_mp(struct net_device *dev, int idx);
 
 /**
diff --git a/net/core/Makefile b/net/core/Makefile
index 9ef2099c5426..d643a5a7fd18 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_NETDEV_ADDR_LIST_TEST) += dev_addr_lists_test.o
 
 obj-y += net-sysfs.o
 obj-y += hotdata.o
+obj-y += netdev_config.o
 obj-y += netdev_rx_queue.o
 obj-y += netdev_queues.o
 obj-$(CONFIG_PAGE_POOL) += page_pool.o page_pool_user.o
diff --git a/net/core/netdev_config.c b/net/core/netdev_config.c
new file mode 100644
index 000000000000..562087bd30c8
--- /dev/null
+++ b/net/core/netdev_config.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/netdevice.h>
+#include <net/netdev_queues.h>
+#include <net/netdev_rx_queue.h>
+
+/**
+ * netdev_queue_config() - get configuration for a given queue
+ * @dev:      net_device instance
+ * @rxq_idx:  index of the queue of interest
+ * @qcfg: queue configuration struct (output)
+ *
+ * Render the configuration for a given queue. This helper should be used
+ * by drivers which support queue configuration to retrieve config for
+ * a particular queue.
+ *
+ * @qcfg is an output parameter and is always fully initialized by this
+ * function. Some values may not be set by the user, drivers may either
+ * deal with the "unset" values in @qcfg, or provide the callback
+ * to populate defaults in queue_management_ops.
+ */
+void netdev_queue_config(struct net_device *dev, int rxq_idx,
+			 struct netdev_queue_config *qcfg)
+{
+	struct netdev_queue_config *stored;
+
+	memset(qcfg, 0, sizeof(*qcfg));
+
+	stored = &__netif_get_rx_queue(dev, rxq_idx)->qcfg;
+	qcfg->rx_page_size = stored->rx_page_size;
+}
+EXPORT_SYMBOL(netdev_queue_config);