net: sysfs: use ops lock for speed and duplex

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Reading /sys/class/net/<dev>/{speed,duplex} takes rtnl_lock() even for
ops-locked devices whose get_link_ksettings callback does not require it.
This unnecessarily serializes monitoring reads with unrelated rtnetlink
operations.

On CPU-throttled hosts, a periodic reader such as node-exporter can hold
RTNL for hundreds of milliseconds while an mlx5 callback runs, delaying
unrelated rtnetlink operations.

Use the netdev instance lock for these devices. Retain sysfs_rtnl_lock()
for legacy devices and callbacks that request
ETHTOOL_OP_NEEDS_RTNL_LINKSETTINGS.

Preserve the existing speed and duplex sysfs ABI, including -EINVAL for
devices that are down or callbacks that fail.

Assisted-by: LLM
Signed-off-by: Wang Zhan <wang.zhan@smartx.com>
Link: https://patch.msgid.link/20260903133314.3703381-3-wang.zhan@smartx.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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Wang Zhan 2026-09-03 21:33:14 +08:00 • committed by Paolo Abeni

parent fc73b71c1b

commit 5d074ded67

1 changed files with 21 additions and 6 deletions

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net/core/net-sysfs.c

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