From: Maxim Mikityanskiy <maximmi@nvidia.com>
Date: Wed, 26 Jan 2022 15:49:23 +0200
Subject: net/mlx5e: Add headroom only to the first fragment in legacy RQ
Patch-mainline: v5.18-rc1
Git-commit: c3cce0fff3a3be0372caa4821be58fc7cefaeb3c
References: jsc#PED-1549

Currently, rq->buff.headroom is applied to all fragments in legacy RQ.
In the linear mode, there is a non-zero headroom, but there is only one
fragment per packet. In the non-linear mode, the headroom is zero.

This commit changes the logic to apply the headroom only to the first
fragment. The current behavior remains the same for both linear and
non-linear modes. However, it allows the next commit to enable headroom
for the non-linear mode, which will be applied only to the first
fragment.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -373,12 +373,15 @@ static int mlx5e_alloc_rx_wqe(struct mlx
 	int i;
 
 	for (i = 0; i < rq->wqe.info.num_frags; i++, frag++) {
+		u16 headroom;
+
 		err = mlx5e_get_rx_frag(rq, frag);
 		if (unlikely(err))
 			goto free_frags;
 
+		headroom = i == 0 ? rq->buff.headroom : 0;
 		wqe->data[i].addr = cpu_to_be64(frag->di->addr +
-						frag->offset + rq->buff.headroom);
+						frag->offset + headroom);
 	}
 
 	return 0;