From a60735875b83703004c3c0cefa1afe5c28bfbb7c Mon Sep 17 00:00:00 2001
From: Alaa Hleihel <ahleihel@redhat.com>
Date: Tue, 12 May 2020 10:54:46 -0400
Subject: [PATCH 174/312] [netdrv] net/mlx5e: Allow mlx5e_switch_priv_channels
 to fail and recover

Message-id: <20200512105530.4207-81-ahleihel@redhat.com>
Patchwork-id: 306952
Patchwork-instance: patchwork
O-Subject: [RHEL8.3 BZ 1789382 080/124] net/mlx5e: Allow mlx5e_switch_priv_channels to fail and recover
Bugzilla: 1789382
RH-Acked-by: Tony Camuso <tcamuso@redhat.com>
RH-Acked-by: Kamal Heib <kheib@redhat.com>
RH-Acked-by: Jarod Wilson <jarod@redhat.com>

Bugzilla: http://bugzilla.redhat.com/1789382
Upstream: v5.7-rc1

commit 35a78ed4c351319e8840d99ba9032bf2d175e168
Author: Maxim Mikityanskiy <maximmi@mellanox.com>
Date:   Wed Nov 13 18:07:29 2019 +0200

    net/mlx5e: Allow mlx5e_switch_priv_channels to fail and recover

    Currently mlx5e_switch_priv_channels expects that the preactivate hook
    doesn't fail, however, it can fail, because it may set hardware
    parameters. This commit addresses this issue and provides a way to
    recover from failures of the preactivate hook: the old channels are not
    closed until the point where nothing can fail anymore, so in case
    preactivate fails, the driver can roll back the old channels and
    activate them again.

    Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
    Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
    Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

Signed-off-by: Alaa Hleihel <ahleihel@redhat.com>
Signed-off-by: Frantisek Hrbata <fhrbata@redhat.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 34 ++++++++++++++++++-----
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index ae91592165ea..390db68727ff 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -2955,33 +2955,45 @@ void mlx5e_deactivate_priv_channels(struct mlx5e_priv *priv)
 	mlx5e_deactivate_channels(&priv->channels);
 }
 
-static void mlx5e_switch_priv_channels(struct mlx5e_priv *priv,
-				       struct mlx5e_channels *new_chs,
-				       mlx5e_fp_preactivate preactivate)
+static int mlx5e_switch_priv_channels(struct mlx5e_priv *priv,
+				      struct mlx5e_channels *new_chs,
+				      mlx5e_fp_preactivate preactivate)
 {
 	struct net_device *netdev = priv->netdev;
+	struct mlx5e_channels old_chs;
 	int carrier_ok;
+	int err = 0;
 
 	carrier_ok = netif_carrier_ok(netdev);
 	netif_carrier_off(netdev);
 
 	mlx5e_deactivate_priv_channels(priv);
-	mlx5e_close_channels(&priv->channels);
 
+	old_chs = priv->channels;
 	priv->channels = *new_chs;
 
 	/* New channels are ready to roll, call the preactivate hook if needed
 	 * to modify HW settings or update kernel parameters.
 	 */
-	if (preactivate)
-		preactivate(priv);
+	if (preactivate) {
+		err = preactivate(priv);
+		if (err) {
+			priv->channels = old_chs;
+			goto out;
+		}
+	}
 
+	mlx5e_close_channels(&old_chs);
 	priv->profile->update_rx(priv);
+
+out:
 	mlx5e_activate_priv_channels(priv);
 
 	/* return carrier back if needed */
 	if (carrier_ok)
 		netif_carrier_on(netdev);
+
+	return err;
 }
 
 int mlx5e_safe_switch_channels(struct mlx5e_priv *priv,
@@ -2994,8 +3006,16 @@ int mlx5e_safe_switch_channels(struct mlx5e_priv *priv,
 	if (err)
 		return err;
 
-	mlx5e_switch_priv_channels(priv, new_chs, preactivate);
+	err = mlx5e_switch_priv_channels(priv, new_chs, preactivate);
+	if (err)
+		goto err_close;
+
 	return 0;
+
+err_close:
+	mlx5e_close_channels(new_chs);
+
+	return err;
 }
 
 int mlx5e_safe_reopen_channels(struct mlx5e_priv *priv)
-- 
2.13.6