net: move mp dev config validation to __net_mp_open_rxq()

devmem code performs a number of safety checks to avoid having
to reimplement all of them in the drivers. Move those to
__net_mp_open_rxq() and reuse that function for binding to make
sure that io_uring ZC also benefits from them.

While at it rename the queue ID variable to rxq_idx in
__net_mp_open_rxq(), we touch most of the relevant lines.

The XArray insertion is reordered after the netdev_rx_queue_restart()
call, otherwise we'd need to duplicate the queue index check
or risk inserting an invalid pointer. The XArray allocation
failures should be extremely rare.

Reviewed-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Fixes: 6e18ed929d3b ("net: add helpers for setting a memory provider on an rx queue")
Link: https://patch.msgid.link/20250403013405.2827250-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 10 insertions, 40 deletions

diff --git a/net/core/devmem.c b/net/core/devmem.c
index ee145a2aa41c..f2ce3c2ebc97 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -8,7 +8,6 @@
  */
 
 #include <linux/dma-buf.h>
-#include <linux/ethtool_netlink.h>
 #include <linux/genalloc.h>
 #include <linux/mm.h>
 #include <linux/netdevice.h>
@@ -143,57 +142,28 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 				    struct net_devmem_dmabuf_binding *binding,
 				    struct netlink_ext_ack *extack)
 {
+	struct pp_memory_provider_params mp_params = {
+		.mp_priv	= binding,
+		.mp_ops		= &dmabuf_devmem_ops,
+	};
 	struct netdev_rx_queue *rxq;
 	u32 xa_idx;
 	int err;
 
-	if (rxq_idx >= dev->real_num_rx_queues) {
-		NL_SET_ERR_MSG(extack, "rx queue index out of range");
-		return -ERANGE;
-	}
-
-	if (dev->cfg->hds_config != ETHTOOL_TCP_DATA_SPLIT_ENABLED) {
-		NL_SET_ERR_MSG(extack, "tcp-data-split is disabled");
-		return -EINVAL;
-	}
-
-	if (dev->cfg->hds_thresh) {
-		NL_SET_ERR_MSG(extack, "hds-thresh is not zero");
-		return -EINVAL;
-	}
+	err = __net_mp_open_rxq(dev, rxq_idx, &mp_params, extack);
+	if (err)
+		return err;
 
 	rxq = __netif_get_rx_queue(dev, rxq_idx);
-	if (rxq->mp_params.mp_ops) {
-		NL_SET_ERR_MSG(extack, "designated queue already memory provider bound");
-		return -EEXIST;
-	}
-
-#ifdef CONFIG_XDP_SOCKETS
-	if (rxq->pool) {
-		NL_SET_ERR_MSG(extack, "designated queue already in use by AF_XDP");
-		return -EBUSY;
-	}
-#endif
-
 	err = xa_alloc(&binding->bound_rxqs, &xa_idx, rxq, xa_limit_32b,
 		       GFP_KERNEL);
 	if (err)
-		return err;
-
-	rxq->mp_params.mp_priv = binding;
-	rxq->mp_params.mp_ops = &dmabuf_devmem_ops;
-
-	err = netdev_rx_queue_restart(dev, rxq_idx);
-	if (err)
-		goto err_xa_erase;
+		goto err_close_rxq;
 
 	return 0;
 
-err_xa_erase:
-	rxq->mp_params.mp_priv = NULL;
-	rxq->mp_params.mp_ops = NULL;
-	xa_erase(&binding->bound_rxqs, xa_idx);
-
+err_close_rxq:
+	__net_mp_close_rxq(dev, rxq_idx, &mp_params);
 	return err;
 }