Re: [PATCH net-next v2 4/4] net: dsa: soce: Add basic support for SoC-e switch IP cores

[Andrew Lunn]

> > After an unbind or rmmod, does the core keep inserting SDSA source-port
> > tags into every frame delivered to the CPU port, with the tagger that
> > would strip them gone?  As described in the commit message, the same bits
> > also keep the user ports in CPU-directed operation:
> > 
> >     "Enabling this tagging feature of the switch, places all user ports
> >     into CPU-directed operation"
> > 
> > so the switch would also stay locked out of normal port-to-port
> > forwarding after the driver is removed.
> 
> Yes, I had not considered this use case. The tagging state currently
> remains enabled after unbind or shutdown. In v3, I will add a .teardown
> callback that clears both SOCE_TAG_ALL_FRAMES_ENABLE and
> SOCE_CUSTOM_RULES_TAGGING_ENABLE, returning the switch to an unmanaged
> state.

I would say the AI is wrong here. If you put the switch into unmanaged
mode, and don't have anything performing spanning tree, your network
could experience a broadcast storm and stop working. The .teardown
should disable all the ports, leaving the network in a safe
configuration.

	Andrew