[PATCH net-next v10 14/22] io_uring/zcrx: grab a net device

[David Wei <dw@davidwei.uk>]

From: Pavel Begunkov <asml.silence@gmail.com>

Zerocopy receive needs a net device to bind to its rx queue and dma map
buffers. As a preparation to following patches, resolve a net device
from the if_idx parameter with no functional changes otherwise.

Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 io_uring/zcrx.c | 10 ++++++++++
 io_uring/zcrx.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 04883a3ae80c..e6cca6747148 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -3,6 +3,8 @@
 #include <linux/errno.h>
 #include <linux/mm.h>
 #include <linux/io_uring.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
 
 #include <uapi/linux/io_uring.h>
 
@@ -136,6 +138,8 @@ static void io_zcrx_ifq_free(struct io_zcrx_ifq *ifq)
 	if (ifq->area)
 		io_zcrx_free_area(ifq->area);
 
+	if (ifq->dev)
+		netdev_put(ifq->dev, &ifq->netdev_tracker);
 	io_free_rbuf_ring(ifq);
 	kfree(ifq);
 }
@@ -195,6 +199,12 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 	ifq->rq_entries = reg.rq_entries;
 	ifq->if_rxq = reg.if_rxq;
 
+	ret = -ENODEV;
+	ifq->dev = netdev_get_by_index(current->nsproxy->net_ns, reg.if_idx,
+					&ifq->netdev_tracker, GFP_KERNEL);
+	if (!ifq->dev)
+		goto err;
+
 	reg.offsets.rqes = sizeof(struct io_uring);
 	reg.offsets.head = offsetof(struct io_uring, head);
 	reg.offsets.tail = offsetof(struct io_uring, tail);
diff --git a/io_uring/zcrx.h b/io_uring/zcrx.h
index 53fd94b65b38..46988a1dbd54 100644
--- a/io_uring/zcrx.h
+++ b/io_uring/zcrx.h
@@ -4,6 +4,7 @@
 
 #include <linux/io_uring_types.h>
 #include <net/page_pool/types.h>
+#include <net/net_trackers.h>
 
 struct io_zcrx_area {
 	struct net_iov_area	nia;
@@ -27,6 +28,8 @@ struct io_zcrx_ifq {
 	u32				rq_entries;
 
 	u32				if_rxq;
+	struct net_device		*dev;
+	netdevice_tracker		netdev_tracker;
 };
 
 #if defined(CONFIG_IO_URING_ZCRX)
-- 
2.43.5