Re: [PATCH net-next 11/12] net: pse-pd: Add support for event reporting using devm_regulator_irq_helper

On Fri, Oct 04, 2024 at 03:56:33PM +0200, Oleksij Rempel wrote:

On Thu, Oct 03, 2024 at 05:22:58PM +0200, Andrew Lunn wrote:

quoted

quoted

Indeed, but regulator API already provide such events, which will even be sent
when we enable or disable the PSE. Should we write a second event management.
Using regulator event API allows to report over current internal events to the
parents regulator the power supply of the PSE which could also do something to
avoid smoke.

Or maybe we should add another wrapper which will send PSE ethtool netlink
notification alongside the regulator notifications supported by this patch.

quoted

Also, how do regulator events work in combination with network
namespaces? If you move the interface into a different network
namespace, do the regulator events get delivered to the root namespace
or the namespace the interface is in?

regulator events are sent in root namespace.

I think we will need two event, the base regulator event, and a
networking event. Since it is a regulator, sending a normal regulator
event makes a lot of sense. But mapping that regulator event to a
netns:ifnam is going to be hard. Anything wanting to take an action is
probably going to want to use ethtool, and so needs to be in the
correct netns, etc. But it does get messy if there is some sort of
software driven prioritisation going on, some daemon needs to pick a
victim to reduce power to, and the interfaces are spread over multiple
network namespaces.

What i don't know is if we can use an existing event, or we should add
a new one. Often rtnetlink_event() is used:

https://elixir.bootlin.com/linux/v6.12-rc1/source/net/core/rtnetlink.c#L6679

but without some PSE information in it, it would be hard to know why
it was sent. So we probably either want a generic ethtool event, or a
PSE event.

Hm... assuming we have following scenario:

                                  .---------   PI 1
                                 / .---------  PI 2
                   .========= PSE /----------( PI 3 ) NNS red
                  //              \----------( PI 4 ) NNS blue
Main supply      //                `---------( PI 5 ) NNS blue
o================´--- System, CPU

In this case we seems to have a new challenge:

On one side, a system wide power manager should see and mange all ports.
On other side, withing a name space, we should be able to play in a
isolated sand box. There is a reason why it is isolated. So, we should
be able to sandbox power delivery and port prios too. Means, by creating
network names space, we will need a power names space. 

I can even imagine a use case: an admin limited access to a switch for
developer. A developer name space is created with PSE budget and max
prios available for this name space. This will prevent users from DoSing
system critical ports.

At this point, creating a power name space will an overkill for this
patch set, so it should be enough to allow controlling prios over
ethtool per port and isolation support if needed.

Oh, sorry, i'm too tired. Too many words are missing in my answer ...

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