netdev - [net V3 12/15] net/mlx5e: Check netdev pointer before checking its net ns

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Date: Tue,  5 Dec 2023 13:45:31 -0800
From: Saeed Mahameed <saeed@...nel.org>
To: "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>
Cc: Saeed Mahameed <saeedm@...dia.com>,
	netdev@...r.kernel.org,
	Tariq Toukan <tariqt@...dia.com>,
	Gavin Li <gavinl@...dia.com>,
	Gavi Teitz <gavi@...dia.com>
Subject: [net V3 12/15] net/mlx5e: Check netdev pointer before checking its net ns

From: Gavin Li <gavinl@...dia.com>

Previously, when comparing the net namespaces, the case where the netdev
doesn't exist wasn't taken into account, and therefore can cause a crash.
In such a case, the comparing function should return false, as there is no
netdev->net to compare the devlink->net to.

Furthermore, this will result in an attempt to enter switchdev mode
without a netdev to fail, and which is the desired result as there is no
meaning in switchdev mode without a net device.

Fixes: 662404b24a4c ("net/mlx5e: Block entering switchdev mode with ns inconsistency")
Signed-off-by: Gavin Li <gavinl@...dia.com>
Reviewed-by: Gavi Teitz <gavi@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 .../mellanox/mlx5/core/eswitch_offloads.c        | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
index bf78eeca401b..bb8bcb448ae9 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
@@ -3653,14 +3653,18 @@ static int esw_inline_mode_to_devlink(u8 mlx5_mode, u8 *mode)
 
 static bool esw_offloads_devlink_ns_eq_netdev_ns(struct devlink *devlink)
 {
+	struct mlx5_core_dev *dev = devlink_priv(devlink);
 	struct net *devl_net, *netdev_net;
-	struct mlx5_eswitch *esw;
-
-	esw = mlx5_devlink_eswitch_nocheck_get(devlink);
-	netdev_net = dev_net(esw->dev->mlx5e_res.uplink_netdev);
-	devl_net = devlink_net(devlink);
+	bool ret = false;
 
-	return net_eq(devl_net, netdev_net);
+	mutex_lock(&dev->mlx5e_res.uplink_netdev_lock);
+	if (dev->mlx5e_res.uplink_netdev) {
+		netdev_net = dev_net(dev->mlx5e_res.uplink_netdev);
+		devl_net = devlink_net(devlink);
+		ret = net_eq(devl_net, netdev_net);
+	}
+	mutex_unlock(&dev->mlx5e_res.uplink_netdev_lock);
+	return ret;
 }
 
 int mlx5_eswitch_block_mode(struct mlx5_core_dev *dev)
-- 
2.43.0