Subject: [net-next 10/15] net/mlx5e: RX, Fix XDP_TX page release for legacy rq nonlinear case

From: Saeed Mahameed <[email-masked]>
Date: Thu, 20 Apr 2023 18:38:45 -0700

From: Dragos Tatulea <[email-masked]>

When the XDP handler marks the data for transmission (XDP_TX),
it is incorrect to release the page fragment. Instead, the
fragments should be marked as MLX5E_WQE_FRAG_SKIP_RELEASE
because XDP will release the page directly to the page_pool
(page_pool_put_defragged_page) after TX completion.

The linear case already does this. This patch fixes the
nonlinear part as well.

Also, the looping over the fragments was incorrect: When handling
pages after XDP_TX in the legacy rq nonlinear case, the loop was
skipping the first wqe fragment.

Fixes: 3f93f82988bc ("net/mlx5e: RX, Defer page release in legacy rq for better recycling")
Signed-off-by: Dragos Tatulea <[email-masked]>
Reviewed-by: Tariq Toukan <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 5dc907541094..69634829558e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -1746,10 +1746,10 @@ mlx5e_skb_from_cqe_nonlinear(struct mlx5e_rq *rq, struct mlx5e_wqe_frag_info *wi
 	prog = rcu_dereference(rq->xdp_prog);
 	if (prog && mlx5e_xdp_handle(rq, prog, &mxbuf)) {
 		if (test_bit(MLX5E_RQ_FLAG_XDP_XMIT, rq->flags)) {
-			int i;
+			struct mlx5e_wqe_frag_info *pwi;
 
-			for (i = wi - head_wi; i < rq->wqe.info.num_frags; i++)
-				mlx5e_put_rx_frag(rq, &head_wi[i]);
+			for (pwi = head_wi; pwi < wi; pwi++)
+				pwi->flags |= BIT(MLX5E_WQE_FRAG_SKIP_RELEASE);
 		}
 		return NULL; /* page/packet was consumed by XDP */
 	}
-- 
2.39.2