Hi Jiri,

On 20/05/18 14:19, Jiri Pirko wrote:

Tue, Mar 27, 2018 at 05:43:08PM CEST, linus.luessing@c0d3.blue wrote:

quoted

On Sat, Oct 29, 2016 at 12:56:28PM +0200, Jiri Pirko wrote:

quoted

quoted

quoted

I strongly believe it is a huge mistake to use sysfs for things like
this. This should be done via generic netlink api.

This doesn't change the problem that it is already that way. This patch
only adds the list of available files to the README.

Sure. Just found out you did it like that. Therefore I commented. I
suggest to rework the api to use genl entirely.

Hi Jiri,

Thanks for sharing your thoughts!

Could you explain a bit more on which disadvantages you see in
the usage of sysfs here?

There are 2 major disadvantages.
1) You don't have any events on a change. An app has to poll in order to
   know what changed in kernel. Netlink handles this by sending
   multicast messages on a specific socket while whoever is interested
   gets the messages.
2) In sysfs, everything is string. There are even mixed values like
   "1 (means something)". There are no well defined values. Every driver
   can expose same things differently. In Netlink, you have well-defined
   attributes, with typed values. You can pass multiple attributes for
   the same value if needed.

In general, usage of sysfs in netdev subsystem is frowned upon. I would
suggest to convert your iface to Generic Netlink API and let the
existing sysfs API to rot.

Do you have any pointer about where this discussion took place? I
imagine it happened in conjunction with some patches intended to other
drivers/netdev changes.

Reading that could give us a sense of how strict/important/severe this
decision was and how to prioritize future work.

I am asking because we have been working on a new feature since several
months and this feature introduces a new sysfs knob.

Now, although I understand the recommendation of switching to netlink, I
find it a bit impractical to delay a new (and fairly big) feature,
simply because it uses a potentially obsolete, but current, API.

Any opinion about this?


Thanks a lot


Regards,


-- 
Antonio Quartulli