On Mon, 24 Mar 2025 11:40:03 +0100
Maxime Chevallier [off-list ref] wrote:

There are a few netlink commands that rely on the req_info->dev field
being populated by ethnl in their ->prepare_data() and ->fill_reply().

For a regular GET request, this will be set by ethnl_default_parse(),
which calls ethnl_parse_header_dev_get().

In the case of a DUMP request, the ->prepare_data() and ->fill_reply()
callbacks will be called with the req_info->dev being NULL, which can
cause discrepancies in the behaviour between GET and DUMP results.

The main impact is that ethnl_req_get_phydev() will not find any
phy_device, impacting :
 - plca
 - pse-pd
 - stats

Some other commands rely on req_info->dev, namely :
 - coalesce in ->fill_reply to look for an irq_moder

Although cable_test and tunnels also rely on req_info->dev being set,
that's not a problem for these commands as :
 - cable_test doesn't support DUMP
 - tunnels rolls its own ->dumpit (and sets dev in the req_info).
 - phy also has its own ->dumpit

All other commands use reply_data->dev (probably the correct way of
doing things) and aren't facing this issue.

Simply set the dev in the req_info context when iterating to dump each
dev.

Tested-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>

Thank you, this fixes the PSE dump!

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com