netdev - [PATCH net-next] net/mlx4_en: avoid indirect call in TX completion

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Date:   Wed, 15 Apr 2020 09:46:52 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net-next] net/mlx4_en: avoid indirect call in TX completion

Commit 9ecc2d86171a ("net/mlx4_en: add xdp forwarding and data write support")
brought another indirect call in fast path.

Use INDIRECT_CALL_2() helper to avoid the cost of the indirect call
when/if CONFIG_RETPOLINE=y

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Tariq Toukan <tariqt@...lanox.com>
Cc: Willem de Bruijn <willemb@...gle.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_tx.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 4d5ca302c067126b8627cb4809485b45c10e2460..a30edb436f4af11526e04c09623840288ebe4a29 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -43,6 +43,7 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/moduleparam.h>
+#include <linux/indirect_call_wrapper.h>
 
 #include "mlx4_en.h"
 
@@ -261,6 +262,10 @@ static void mlx4_en_stamp_wqe(struct mlx4_en_priv *priv,
 	}
 }
 
+INDIRECT_CALLABLE_DECLARE(u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
+						   struct mlx4_en_tx_ring *ring,
+						   int index, u64 timestamp,
+						   int napi_mode));
 
 u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
 			 struct mlx4_en_tx_ring *ring,
@@ -329,6 +334,11 @@ u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
 	return tx_info->nr_txbb;
 }
 
+INDIRECT_CALLABLE_DECLARE(u32 mlx4_en_recycle_tx_desc(struct mlx4_en_priv *priv,
+						      struct mlx4_en_tx_ring *ring,
+						      int index, u64 timestamp,
+						      int napi_mode));
+
 u32 mlx4_en_recycle_tx_desc(struct mlx4_en_priv *priv,
 			    struct mlx4_en_tx_ring *ring,
 			    int index, u64 timestamp,
@@ -449,7 +459,9 @@ bool mlx4_en_process_tx_cq(struct net_device *dev,
 				timestamp = mlx4_en_get_cqe_ts(cqe);
 
 			/* free next descriptor */
-			last_nr_txbb = ring->free_tx_desc(
+			last_nr_txbb = INDIRECT_CALL_2(ring->free_tx_desc,
+						       mlx4_en_free_tx_desc,
+						       mlx4_en_recycle_tx_desc,
 					priv, ring, ring_index,
 					timestamp, napi_budget);
 
-- 
2.26.0.110.g2183baf09c-goog