linux-kernel - [RFC net-next v3 2/7] io_uring/zcrx: add support for custom DMA devices

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Message-ID: <20250815110401.2254214-4-dtatulea@nvidia.com>
Date: Fri, 15 Aug 2025 14:03:43 +0300
From: Dragos Tatulea <dtatulea@...dia.com>
To: <almasrymina@...gle.com>, <asml.silence@...il.com>, Jens Axboe
	<axboe@...nel.dk>
CC: Dragos Tatulea <dtatulea@...dia.com>, <cratiu@...dia.com>,
	<tariqt@...dia.com>, <parav@...dia.com>, Christoph Hellwig
	<hch@...radead.org>, <io-uring@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [RFC net-next v3 2/7] io_uring/zcrx: add support for custom DMA devices

Use the new API for getting a DMA device for a specific netdev queue.

This patch will allow io_uring zero-copy rx to work with devices
where the DMA device is not stored in the parent device. mlx5 SFs
are an example of such a device.

Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
---
 io_uring/zcrx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index e5ff49f3425e..319eddfd30e0 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -12,6 +12,7 @@
 #include <net/page_pool/helpers.h>
 #include <net/page_pool/memory_provider.h>
 #include <net/netlink.h>
+#include <net/netdev_queues.h>
 #include <net/netdev_rx_queue.h>
 #include <net/tcp.h>
 #include <net/rps.h>
@@ -599,7 +600,7 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 		goto err;
 	}
 
-	ifq->dev = ifq->netdev->dev.parent;
+	ifq->dev = netdev_queue_get_dma_dev(ifq->netdev, ifq->if_rxq);
 	if (!ifq->dev) {
 		ret = -EOPNOTSUPP;
 		goto err;
-- 
2.50.1