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Merge branch 'mlxsw-make-the-driver-ops-locked'

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Ido Schimmel says:

====================
mlxsw: Make the driver ops-locked

Make the driver ops-locked in order to allow ethtool operations to be
invoked without RTNL being held.

An ops-locked driver has most of its NDOs, all of its ethtool operations
and some net device notifications run with the netdev instance lock
held.

In the specific case of mlxsw, the driver is not using any functions
that acquire this lock nor functions that expect the lock to be held for
an ops-locked driver. Therefore, converting its NDOs to run with the
lock being held is trivial except for a small quirk which is handled in
patch #1.

The driver does not generate any net device notifications, so there is
no risk of nested notifications of the ops-locked types. For the
notifications that run under the instance lock, RTNL is also held, and
the driver does not acquire the instance lock itself, so no changes are
required in its notifier handling.

Ethtool operations can be invoked without RTNL except for two operations
that are annotated in patch #2.

Lastly, patch #3 converts the driver to be ops-locked.

A probe on rtnl_lock() shows it is no longer taken when dumping
statistics:

 # perf probe --add rtnl_lock

Before:

 # perf stat -e probe:rtnl_lock -- ethtool -S swp1 --all-groups
 [...]
                  1      probe:rtnl_lock

After:

 # perf stat -e probe:rtnl_lock -- ethtool -S swp1 --all-groups
 [...]
                  0      probe:rtnl_lock

No issues were reported after running a full regression with a debug
config that has lockdep enabled.
====================

Link: https://patch.msgid.link/20260708123933.1303291-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Paolo Abeni 2026-07-21 12:43:46 +02:00
commit e0722efbcf
2 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/net/ethernet/mellanox/mlxsw/spectrum.c
View File

@ -663,8 +663,11 @@ static netdev_tx_t mlxsw_sp_port_xmit(struct sk_buff *skb,
return NETDEV_TX_OK;
}
static void mlxsw_sp_set_rx_mode(struct net_device *dev)
static int mlxsw_sp_set_rx_mode_async(struct net_device *dev,
struct netdev_hw_addr_list *uc,
struct netdev_hw_addr_list *mc)
{
return 0;
}
static int mlxsw_sp_port_set_mac_address(struct net_device *dev, void *p)
@ -1191,7 +1194,7 @@ static const struct net_device_ops mlxsw_sp_port_netdev_ops = {
.ndo_stop = mlxsw_sp_port_stop,
.ndo_start_xmit = mlxsw_sp_port_xmit,
.ndo_setup_tc = mlxsw_sp_setup_tc,
.ndo_set_rx_mode = mlxsw_sp_set_rx_mode,
.ndo_set_rx_mode_async = mlxsw_sp_set_rx_mode_async,
.ndo_set_mac_address = mlxsw_sp_port_set_mac_address,
.ndo_change_mtu = mlxsw_sp_port_change_mtu,
.ndo_get_stats64 = mlxsw_sp_port_get_stats64,
@ -1549,6 +1552,7 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u16 local_port,
dev->vlan_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
dev->lltx = true;
dev->netns_immutable = true;
dev->request_ops_lock = true;
dev->min_mtu = ETH_MIN_MTU;
dev->max_mtu = MLXSW_PORT_MAX_MTU - MLXSW_PORT_ETH_FRAME_HDR;

2
drivers/net/ethernet/mellanox/mlxsw/spectrum_ethtool.c
View File

@ -1262,6 +1262,8 @@ mlxsw_sp_set_module_power_mode(struct net_device *dev,
const struct ethtool_ops mlxsw_sp_port_ethtool_ops = {
.cap_link_lanes_supported = true,
.op_needs_rtnl = ETHTOOL_OP_NEEDS_RTNL_SPAUSEPARAM |
ETHTOOL_OP_NEEDS_RTNL_GLINK,
.get_drvinfo = mlxsw_sp_port_get_drvinfo,
.get_link = ethtool_op_get_link,
.get_link_ext_state = mlxsw_sp_port_get_link_ext_state,