Merge branch 'net-restore-the-structure-of-driver-facing-qcfg-api'

Jakub Kicinski says:

====================
net: restore the structure of driver-facing qcfg API

The goal of qcfg objects is to let us seamlessly support new use cases
without modifying all the drivers. We want to pull all the logic of
combining configuration supplied via different interfaces into the core
and present the drivers with a flat queue-by-queue configuration.
Additionally we want to separate the current effective configuration
from the user intent (default vs user setting vs memory provider setting).

Restructure the recently added code to re-introduce the pieces that
are missing compared to the old RFC:
https://lore.kernel.org/20250421222827.283737-1-kuba@kernel.org
Namely:
 - the netdev_queue_config() helper
 - queue config validation callback

I hopefully removed all the more "out there" parts of the RFC.
====================

Link: https://patch.msgid.link/20260122005113.2476634-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 38 insertions, 22 deletions

diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index b81cad90ba2f..668a90658f25 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -7,6 +7,7 @@
 #include <net/netdev_rx_queue.h>
 #include <net/page_pool/memory_provider.h>
 
+#include "dev.h"
 #include "page_pool_priv.h"
 
 /* See also page_pool_is_unreadable() */
@@ -18,11 +19,13 @@ bool netif_rxq_has_unreadable_mp(struct net_device *dev, int idx)
 }
 EXPORT_SYMBOL(netif_rxq_has_unreadable_mp);
 
-int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
+static int netdev_rx_queue_reconfig(struct net_device *dev,
+				    unsigned int rxq_idx,
+				    struct netdev_queue_config *qcfg_old,
+				    struct netdev_queue_config *qcfg_new)
 {
 	struct netdev_rx_queue *rxq = __netif_get_rx_queue(dev, rxq_idx);
 	const struct netdev_queue_mgmt_ops *qops = dev->queue_mgmt_ops;
-	struct netdev_queue_config qcfg;
 	void *new_mem, *old_mem;
 	int err;
 
@@ -30,21 +33,8 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 	    !qops->ndo_queue_mem_alloc || !qops->ndo_queue_start)
 		return -EOPNOTSUPP;
 
-	if (WARN_ON_ONCE(qops->supported_params && !qops->ndo_default_qcfg))
-		return -EINVAL;
-
 	netdev_assert_locked(dev);
 
-	memset(&qcfg, 0, sizeof(qcfg));
-	if (qops->ndo_default_qcfg)
-		qops->ndo_default_qcfg(dev, &qcfg);
-
-	if (rxq->mp_params.rx_page_size) {
-		if (!(qops->supported_params & QCFG_RX_PAGE_SIZE))
-			return -EOPNOTSUPP;
-		qcfg.rx_page_size = rxq->mp_params.rx_page_size;
-	}
-
 	new_mem = kvzalloc(qops->ndo_queue_mem_size, GFP_KERNEL);
 	if (!new_mem)
 		return -ENOMEM;
@@ -55,7 +45,7 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 		goto err_free_new_mem;
 	}
 
-	err = qops->ndo_queue_mem_alloc(dev, &qcfg, new_mem, rxq_idx);
+	err = qops->ndo_queue_mem_alloc(dev, qcfg_new, new_mem, rxq_idx);
 	if (err)
 		goto err_free_old_mem;
 
@@ -68,7 +58,7 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 		if (err)
 			goto err_free_new_queue_mem;
 
-		err = qops->ndo_queue_start(dev, &qcfg, new_mem, rxq_idx);
+		err = qops->ndo_queue_start(dev, qcfg_new, new_mem, rxq_idx);
 		if (err)
 			goto err_start_queue;
 	} else {
@@ -80,7 +70,6 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 	kvfree(old_mem);
 	kvfree(new_mem);
 
-	rxq->qcfg = qcfg;
 	return 0;
 
 err_start_queue:
@@ -91,7 +80,7 @@ err_start_queue:
 	 * WARN if we fail to recover the old rx queue, and at least free
 	 * old_mem so we don't also leak that.
 	 */
-	if (qops->ndo_queue_start(dev, &rxq->qcfg, old_mem, rxq_idx)) {
+	if (qops->ndo_queue_start(dev, qcfg_old, old_mem, rxq_idx)) {
 		WARN(1,
 		     "Failed to restart old queue in error path. RX queue %d may be unhealthy.",
 		     rxq_idx);
@@ -109,12 +98,22 @@ err_free_new_mem:
 
 	return err;
 }
+
+int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
+{
+	struct netdev_queue_config qcfg;
+
+	netdev_queue_config(dev, rxq_idx, &qcfg);
+	return netdev_rx_queue_reconfig(dev, rxq_idx, &qcfg, &qcfg);
+}
 EXPORT_SYMBOL_NS_GPL(netdev_rx_queue_restart, "NETDEV_INTERNAL");
 
 int __net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 		      const struct pp_memory_provider_params *p,
 		      struct netlink_ext_ack *extack)
 {
+	const struct netdev_queue_mgmt_ops *qops = dev->queue_mgmt_ops;
+	struct netdev_queue_config qcfg[2];
 	struct netdev_rx_queue *rxq;
 	int ret;
 
@@ -139,6 +138,10 @@ int __net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 		NL_SET_ERR_MSG(extack, "unable to custom memory provider to device with XDP program attached");
 		return -EEXIST;
 	}
+	if (p->rx_page_size && !(qops->supported_params & QCFG_RX_PAGE_SIZE)) {
+		NL_SET_ERR_MSG(extack, "device does not support: rx_page_size");
+		return -EOPNOTSUPP;
+	}
 
 	rxq = __netif_get_rx_queue(dev, rxq_idx);
 	if (rxq->mp_params.mp_ops) {
@@ -152,11 +155,20 @@ int __net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 	}
 #endif
 
+	netdev_queue_config(dev, rxq_idx, &qcfg[0]);
 	rxq->mp_params = *p;
-	ret = netdev_rx_queue_restart(dev, rxq_idx);
+	ret = netdev_queue_config_validate(dev, rxq_idx, &qcfg[1], extack);
 	if (ret)
-		memset(&rxq->mp_params, 0, sizeof(rxq->mp_params));
+		goto err_clear_mp;
 
+	ret = netdev_rx_queue_reconfig(dev, rxq_idx, &qcfg[0], &qcfg[1]);
+	if (ret)
+		goto err_clear_mp;
+
+	return 0;
+
+err_clear_mp:
+	memset(&rxq->mp_params, 0, sizeof(rxq->mp_params));
 	return ret;
 }
 
@@ -174,6 +186,7 @@ int net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 void __net_mp_close_rxq(struct net_device *dev, unsigned int ifq_idx,
 			const struct pp_memory_provider_params *old_p)
 {
+	struct netdev_queue_config qcfg[2];
 	struct netdev_rx_queue *rxq;
 	int err;
 
@@ -193,8 +206,11 @@ void __net_mp_close_rxq(struct net_device *dev, unsigned int ifq_idx,
 			 rxq->mp_params.mp_priv != old_p->mp_priv))
 		return;
 
+	netdev_queue_config(dev, ifq_idx, &qcfg[0]);
 	memset(&rxq->mp_params, 0, sizeof(rxq->mp_params));
-	err = netdev_rx_queue_restart(dev, ifq_idx);
+	netdev_queue_config(dev, ifq_idx, &qcfg[1]);
+
+	err = netdev_rx_queue_reconfig(dev, ifq_idx, &qcfg[0], &qcfg[1]);
 	WARN_ON(err && err != -ENETDOWN);
 }