netdev - [PATCH net-next 2/7] mlxsw: spectrum_nve: Do not take reference when looking up netdevice

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Date: Thu, 27 Jul 2023 17:59:20 +0200
From: Petr Machata <petrm@...dia.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, <netdev@...r.kernel.org>
CC: Ido Schimmel <idosch@...dia.com>, Petr Machata <petrm@...dia.com>,
	<mlxsw@...dia.com>
Subject: [PATCH net-next 2/7] mlxsw: spectrum_nve: Do not take reference when looking up netdevice

mlxsw_sp_nve_fid_disable() is always called under RTNL. It is therefore
safe to call __dev_get_by_index() to get the netdevice pointer without
bumping the reference count, because we can be sure the netdevice is not
going away. That then obviates the need to put the netdevice later in the
function.

Signed-off-by: Petr Machata <petrm@...dia.com>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_nve.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_nve.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_nve.c
index d2b57a045aa4..5479a1c19d2e 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_nve.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_nve.c
@@ -989,6 +989,9 @@ void mlxsw_sp_nve_fid_disable(struct mlxsw_sp *mlxsw_sp,
 	int nve_ifindex;
 	__be32 vni;
 
+	/* Necessary for __dev_get_by_index() below. */
+	ASSERT_RTNL();
+
 	mlxsw_sp_nve_flood_ip_flush(mlxsw_sp, fid);
 	mlxsw_sp_nve_fdb_flush_by_fid(mlxsw_sp, fid_index);
 	mlxsw_sp_nve_ipv6_addr_flush_by_fid(mlxsw_sp, fid_index);
@@ -997,15 +1000,13 @@ void mlxsw_sp_nve_fid_disable(struct mlxsw_sp *mlxsw_sp,
 		    mlxsw_sp_fid_vni(fid, &vni)))
 		goto out;
 
-	nve_dev = dev_get_by_index(mlxsw_sp_net(mlxsw_sp), nve_ifindex);
+	nve_dev = __dev_get_by_index(mlxsw_sp_net(mlxsw_sp), nve_ifindex);
 	if (!nve_dev)
 		goto out;
 
 	mlxsw_sp_nve_fdb_clear_offload(mlxsw_sp, fid, nve_dev, vni);
 	mlxsw_sp_fid_fdb_clear_offload(fid, nve_dev);
 
-	dev_put(nve_dev);
-
 out:
 	mlxsw_sp_fid_vni_clear(fid);
 	mlxsw_sp_nve_tunnel_fini(mlxsw_sp);
-- 
2.41.0