Merge branch 'xdp-page_pool-fixes-and-in-flight-accounting'

Jesper Dangaard Brouer says:

====================
xdp: page_pool fixes and in-flight accounting

This patchset fix page_pool API and users, such that drivers can use it for
DMA-mapping. A number of places exist, where the DMA-mapping would not get
released/unmapped, all these are fixed. This occurs e.g. when an xdp_frame
gets converted to an SKB. As network stack doesn't have any callback for XDP
memory models.

The patchset also address a shutdown race-condition. Today removing a XDP
memory model, based on page_pool, is only delayed one RCU grace period. This
isn't enough as redirected xdp_frames can still be in-flight on different
queues (remote driver TX, cpumap or veth).

We stress that when drivers use page_pool for DMA-mapping, then they MUST
use one packet per page. This might change in the future, but more work lies
ahead, before we can lift this restriction.

This patchset change the page_pool API to be more strict, as in-flight page
accounting is added.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 8 insertions, 8 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index a8e8350b38aa..5e40db8f92e6 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -545,8 +545,10 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
 	}
 	err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq,
 					 MEM_TYPE_PAGE_POOL, rq->page_pool);
-	if (err)
+	if (err) {
+		page_pool_free(rq->page_pool);
 		goto err_free;
+	}
 
 	for (i = 0; i < wq_sz; i++) {
 		if (rq->wq_type == MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ) {
@@ -611,8 +613,6 @@ err_rq_wq_destroy:
 	if (rq->xdp_prog)
 		bpf_prog_put(rq->xdp_prog);
 	xdp_rxq_info_unreg(&rq->xdp_rxq);
-	if (rq->page_pool)
-		page_pool_destroy(rq->page_pool);
 	mlx5_wq_destroy(&rq->wq_ctrl);
 
 	return err;
@@ -625,10 +625,6 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq)
 	if (rq->xdp_prog)
 		bpf_prog_put(rq->xdp_prog);
 
-	xdp_rxq_info_unreg(&rq->xdp_rxq);
-	if (rq->page_pool)
-		page_pool_destroy(rq->page_pool);
-
 	switch (rq->wq_type) {
 	case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
 		kvfree(rq->mpwqe.info);
@@ -645,6 +641,8 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq)
 
 		mlx5e_page_release(rq, dma_info, false);
 	}
+
+	xdp_rxq_info_unreg(&rq->xdp_rxq);
 	mlx5_wq_destroy(&rq->wq_ctrl);
 }
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 935bf62eddc1..234a3fd39901 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -248,7 +248,7 @@ static inline int mlx5e_page_alloc_mapped(struct mlx5e_rq *rq,
 	dma_info->addr = dma_map_page(rq->pdev, dma_info->page, 0,
 				      PAGE_SIZE, rq->buff.map_dir);
 	if (unlikely(dma_mapping_error(rq->pdev, dma_info->addr))) {
-		put_page(dma_info->page);
+		page_pool_recycle_direct(rq->page_pool, dma_info->page);
 		dma_info->page = NULL;
 		return -ENOMEM;
 	}
@@ -272,6 +272,7 @@ void mlx5e_page_release(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info,
 		page_pool_recycle_direct(rq->page_pool, dma_info->page);
 	} else {
 		mlx5e_page_dma_unmap(rq, dma_info);
+		page_pool_release_page(rq->page_pool, dma_info->page);
 		put_page(dma_info->page);
 	}
 }
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 52110e54e621..c6916bf1017b 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -547,6 +547,7 @@ static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,
 		goto err;
 	}
 
+	xdp_release_frame(frame);
 	xdp_scrub_frame(frame);
 	skb->protocol = eth_type_trans(skb, rq->dev);
 err: