From: Maxim Mikityanskiy <maximmi@mellanox.com>
Date: Mon, 1 Feb 2021 14:01:27 +0200
Subject: net/mlx5e: Replace synchronize_rcu with synchronize_net
Patch-mainline: v5.12-rc1
Git-commit: 4d6e6b0c6d4bed8a7128500701354e2dc6098fa3
References: jsc#SLE-15172

The commit cited below switched from using napi_synchronize to
synchronize_rcu to have a guarantee that it will finish in finite time.
However, on average, synchronize_rcu takes more time than
napi_synchronize. Given that it's called multiple times per channel on
deactivation, it accumulates to a significant amount, which causes
timeouts in some applications (for example, when using bonding with
NetworkManager).

This commit replaces synchronize_rcu with synchronize_net, which is
faster when called under rtnl_lock, allowing to speed up the described
flow.

Fixes: 9c25a22dfb00 ("net/mlx5e: Use synchronize_rcu to sync with NAPI")
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.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/xdp.h           |    2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c     |    2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c |    2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c          |    8 ++++----
 4 files changed, 7 insertions(+), 7 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
@@ -98,7 +98,7 @@ static inline void mlx5e_xdp_tx_disable(
 
 	clear_bit(MLX5E_STATE_XDP_TX_ENABLED, &priv->state);
 	/* Let other device's napi(s) and XSK wakeups see our new state. */
-	synchronize_rcu();
+	synchronize_net();
 }
 
 static inline bool mlx5e_xdp_tx_is_enabled(struct mlx5e_priv *priv)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c
@@ -106,7 +106,7 @@ err_free_cparam:
 void mlx5e_close_xsk(struct mlx5e_channel *c)
 {
 	clear_bit(MLX5E_CHANNEL_STATE_XSK, c->state);
-	synchronize_rcu(); /* Sync with the XSK wakeup and with NAPI. */
+	synchronize_net(); /* Sync with the XSK wakeup and with NAPI. */
 
 	mlx5e_close_rq(&c->xskrq);
 	mlx5e_close_cq(&c->xskrq.cq);
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
@@ -663,7 +663,7 @@ void mlx5e_ktls_del_rx(struct net_device
 	priv_rx = mlx5e_get_ktls_rx_priv_ctx(tls_ctx);
 	set_bit(MLX5E_PRIV_RX_FLAG_DELETING, priv_rx->flags);
 	mlx5e_set_ktls_rx_priv_ctx(tls_ctx, NULL);
-	synchronize_rcu(); /* Sync with NAPI */
+	synchronize_net(); /* Sync with NAPI */
 	if (!cancel_work_sync(&priv_rx->rule.work))
 		/* completion is needed, as the priv_rx in the add flow
 		 * is maintained on the wqe info (wi), not on the socket.
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -913,7 +913,7 @@ void mlx5e_activate_rq(struct mlx5e_rq *
 void mlx5e_deactivate_rq(struct mlx5e_rq *rq)
 {
 	clear_bit(MLX5E_RQ_STATE_ENABLED, &rq->state);
-	synchronize_rcu(); /* Sync with NAPI to prevent mlx5e_post_rx_wqes. */
+	synchronize_net(); /* Sync with NAPI to prevent mlx5e_post_rx_wqes. */
 }
 
 void mlx5e_close_rq(struct mlx5e_rq *rq)
@@ -1361,7 +1361,7 @@ static void mlx5e_deactivate_txqsq(struc
 	struct mlx5_wq_cyc *wq = &sq->wq;
 
 	clear_bit(MLX5E_SQ_STATE_ENABLED, &sq->state);
-	synchronize_rcu(); /* Sync with NAPI to prevent netif_tx_wake_queue. */
+	synchronize_net(); /* Sync with NAPI to prevent netif_tx_wake_queue. */
 
 	mlx5e_tx_disable_queue(sq->txq);
 
@@ -1437,7 +1437,7 @@ void mlx5e_activate_icosq(struct mlx5e_i
 void mlx5e_deactivate_icosq(struct mlx5e_icosq *icosq)
 {
 	clear_bit(MLX5E_SQ_STATE_ENABLED, &icosq->state);
-	synchronize_rcu(); /* Sync with NAPI. */
+	synchronize_net(); /* Sync with NAPI. */
 }
 
 void mlx5e_close_icosq(struct mlx5e_icosq *sq)
@@ -1516,7 +1516,7 @@ void mlx5e_close_xdpsq(struct mlx5e_xdps
 	struct mlx5e_channel *c = sq->channel;
 
 	clear_bit(MLX5E_SQ_STATE_ENABLED, &sq->state);
-	synchronize_rcu(); /* Sync with NAPI. */
+	synchronize_net(); /* Sync with NAPI. */
 
 	mlx5e_destroy_sq(c->mdev, sq->sqn);
 	mlx5e_free_xdpsq_descs(sq);