[PATCH v1 14/15] io_uring/zcrx: set pp memory provider for an rx queue

[David Wei <dw@davidwei.uk>]

From: David Wei <davidhwei@meta.com>

Set the page pool memory provider for the rx queue configured for zero copy to
io_uring. Then the rx queue is reset using netdev_rx_queue_restart() and netdev
core + page pool will take care of filling the rx queue from the io_uring zero
copy memory provider.

For now, there is only one ifq so its destruction happens implicitly during
io_uring cleanup.

Signed-off-by: David Wei <dw@davidwei.uk>
---
 io_uring/zcrx.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index d21e7017deb3..7939f830cf5b 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -6,6 +6,8 @@
 #include <linux/netdevice.h>
 #include <linux/io_uring.h>
 #include <linux/skbuff_ref.h>
+#include <linux/io_uring/net.h>
+#include <net/netdev_rx_queue.h>
 #include <net/busy_poll.h>
 #include <net/page_pool/helpers.h>
 #include <trace/events/page_pool.h>
@@ -49,6 +51,63 @@ static inline struct page *io_zcrx_iov_page(const struct net_iov *niov)
 	return area->pages[net_iov_idx(niov)];
 }
 
+static int io_open_zc_rxq(struct io_zcrx_ifq *ifq, unsigned ifq_idx)
+{
+	struct netdev_rx_queue *rxq;
+	struct net_device *dev = ifq->dev;
+	int ret;
+
+	ASSERT_RTNL();
+
+	if (ifq_idx >= dev->num_rx_queues)
+		return -EINVAL;
+	ifq_idx = array_index_nospec(ifq_idx, dev->num_rx_queues);
+
+	rxq = __netif_get_rx_queue(ifq->dev, ifq_idx);
+	if (rxq->mp_params.mp_priv)
+		return -EEXIST;
+
+	ifq->if_rxq = ifq_idx;
+	rxq->mp_params.mp_ops = &io_uring_pp_zc_ops;
+	rxq->mp_params.mp_priv = ifq;
+	ret = netdev_rx_queue_restart(ifq->dev, ifq->if_rxq);
+	if (ret) {
+		rxq->mp_params.mp_ops = NULL;
+		rxq->mp_params.mp_priv = NULL;
+		ifq->if_rxq = -1;
+	}
+	return ret;
+}
+
+static void io_close_zc_rxq(struct io_zcrx_ifq *ifq)
+{
+	struct netdev_rx_queue *rxq;
+	int err;
+
+	if (ifq->if_rxq == -1)
+		return;
+
+	rtnl_lock();
+	if (WARN_ON_ONCE(ifq->if_rxq >= ifq->dev->num_rx_queues)) {
+		rtnl_unlock();
+		return;
+	}
+
+	rxq = __netif_get_rx_queue(ifq->dev, ifq->if_rxq);
+
+	WARN_ON_ONCE(rxq->mp_params.mp_priv != ifq);
+
+	rxq->mp_params.mp_ops = NULL;
+	rxq->mp_params.mp_priv = NULL;
+
+	err = netdev_rx_queue_restart(ifq->dev, ifq->if_rxq);
+	if (err)
+		pr_devel("io_uring: can't restart a queue on zcrx close\n");
+
+	rtnl_unlock();
+	ifq->if_rxq = -1;
+}
+
 static int io_allocate_rbuf_ring(struct io_zcrx_ifq *ifq,
 				 struct io_uring_zcrx_ifq_reg *reg)
 {
@@ -169,9 +228,12 @@ static struct io_zcrx_ifq *io_zcrx_ifq_alloc(struct io_ring_ctx *ctx)
 
 static void io_zcrx_ifq_free(struct io_zcrx_ifq *ifq)
 {
+	io_close_zc_rxq(ifq);
+
 	if (ifq->area)
 		io_zcrx_free_area(ifq->area);
-
+	if (ifq->dev)
+		dev_put(ifq->dev);
 	io_free_rbuf_ring(ifq);
 	kfree(ifq);
 }
@@ -227,7 +289,17 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 		goto err;
 
 	ifq->rq_entries = reg.rq_entries;
-	ifq->if_rxq = reg.if_rxq;
+
+	ret = -ENODEV;
+	rtnl_lock();
+	ifq->dev = dev_get_by_index(current->nsproxy->net_ns, reg.if_idx);
+	if (!ifq->dev)
+		goto err_rtnl_unlock;
+
+	ret = io_open_zc_rxq(ifq, reg.if_rxq);
+	if (ret)
+		goto err_rtnl_unlock;
+	rtnl_unlock();
 
 	ring_sz = sizeof(struct io_uring);
 	rqes_sz = sizeof(struct io_uring_zcrx_rqe) * ifq->rq_entries;
@@ -237,15 +309,20 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 	reg.offsets.tail = offsetof(struct io_uring, tail);
 
 	if (copy_to_user(arg, &reg, sizeof(reg))) {
+		io_close_zc_rxq(ifq);
 		ret = -EFAULT;
 		goto err;
 	}
 	if (copy_to_user(u64_to_user_ptr(reg.area_ptr), &area, sizeof(area))) {
+		io_close_zc_rxq(ifq);
 		ret = -EFAULT;
 		goto err;
 	}
 	ctx->ifq = ifq;
 	return 0;
+
+err_rtnl_unlock:
+	rtnl_unlock();
 err:
 	io_zcrx_ifq_free(ifq);
 	return ret;
@@ -267,6 +344,9 @@ void io_unregister_zcrx_ifqs(struct io_ring_ctx *ctx)
 void io_shutdown_zcrx_ifqs(struct io_ring_ctx *ctx)
 {
 	lockdep_assert_held(&ctx->uring_lock);
+
+	if (ctx->ifq)
+		io_close_zc_rxq(ctx->ifq);
 }
 
 static void io_zcrx_get_buf_uref(struct net_iov *niov)
-- 
2.43.5