[PATCH net-next] mlx4: handle non-napi callers to napi_poll

[Jonathan Lemon]

From: Jonathan Lemon <b...@fb.com>

netcons calls napi_poll with a budget of 0 to transmit packets.
Handle this by:
 - skipping RX processing
 - do not try to recycle TX packets to the RX cache

Signed-off-by: Jonathan Lemon <jonathan.le...@gmail.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c | 3 +++
 drivers/net/ethernet/mellanox/mlx4/en_tx.c | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c 
b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 99d7737e8ad6..502d1b97855c 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -943,6 +943,9 @@ int mlx4_en_poll_rx_cq(struct napi_struct *napi, int budget)
        bool clean_complete = true;
        int done;
 
+       if (!budget)
+               return 0;
+
        if (priv->tx_ring_num[TX_XDP]) {
                xdp_tx_cq = priv->tx_cq[TX_XDP][cq->ring];
                if (xdp_tx_cq->xdp_busy) {
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c 
b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 45869b29368f..3ddb7268e415 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -350,7 +350,7 @@ u32 mlx4_en_recycle_tx_desc(struct mlx4_en_priv *priv,
                .dma = tx_info->map0_dma,
        };
 
-       if (!mlx4_en_rx_recycle(ring->recycle_ring, &frame)) {
+       if (!napi_mode || !mlx4_en_rx_recycle(ring->recycle_ring, &frame)) {
                dma_unmap_page(priv->ddev, tx_info->map0_dma,
                               PAGE_SIZE, priv->dma_dir);
                put_page(tx_info->page);
-- 
2.24.1