Re: [PATCH net-next] net: sysfs: use ops lock for speed and duplex

[Jakub Kicinski <kuba@kernel.org>]

On Mon, 31 Aug 2026 16:06:23 +0800 Wang Zhan wrote:
> Reading /sys/class/net/<dev>/{speed,duplex} takes rtnl_lock() before
> calling __ethtool_get_link_ksettings(). For ops-locked devices whose
> callbacks do not require RTNL, this unnecessarily serializes sysfs
> readers with rtnetlink users. On CPU-throttled hosts, a periodic reader
> such as node-exporter can keep RTNL held for hundreds of milliseconds
> while an mlx5 callback runs.
> 
> Ops-locked devices can run ethtool operations under the netdev instance
> lock. The ethtool netlink and ioctl paths use
> ETHTOOL_OP_NEEDS_RTNL_LINKSETTINGS to identify callbacks that still need
> RTNL, but the sysfs path currently does not. Apply the same rule to sysfs
> reads: call netif_get_link_ksettings() under netdev_lock_ops() when the
> callback does not require RTNL, and keep sysfs_rtnl_lock() for legacy
> devices and callbacks that opt in to RTNL.
> 
> Preserve the existing speed and duplex sysfs ABI, including -EINVAL for
> devices that are down or callbacks that fail.
> 
> Assisted-by: LLM

The diff is too ugly to look at. Learn how to break up your changes to
make them reviewable.
-- 
pw-bot: cr
pv-bot: slop