Re: [PATCH 04/14] SIWv2: Module initialization: siw_main.c

[Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>]

On 06/30/2011 11:23 AM, Bernard Metzler wrote:
> Good point. I moved the three attributes to debugfs which
> looks much more appropriate.
>
> I also re-structured module initialization/device registration:
> The siw module now registers with the netdevice subsystem
> (register_netdevice_notifier()) to catch NETDEV_xx events,
> which now also handles device state changes and later
> device addition.
>
> Before posting it as a proposed patch I wanted to discuss the
> following. Currently, only NETDEV_REGISTER, NETDEV_UNREGISTER,
> NETDEV_UP, NETDEV_DOWN are handled as following:
> NETDEV_REGISTER:	Instantiate a siw device (ib_alloc_device()).
> NETDEV_UP:		Register to ib_core (ib_register_device()),
> 			if the device has an interface address.
> NETDEV_DOWN:	Unregister from ib_core (ib_unregister_device()).
> NETDEV_UNREGISTER:Deallocate device (ib_dealloc_device())
>
> Toggling the device UP and DOWN would end up un-/registering
> with the ib_core. Maybe thats not appropriate and the device
> should remain visible to ib_core? The CM appears to exclude
> DOWN devices from connection management. With that, a siw device
> would remain visible to ib_core until it gets UNREGISTERed.
>

I would keep it registered if the netdev device is registered.  Wouldn't a SIW connection survive an ifdown/ifup on the 
interface handling that connection? I would think so.  So I think NETDEV_REGISTER triggers rdma core alloc and 
registration, UP/DOWN trigger IB_EVENT_PORT_ACTIVE/IB_EVENT_PORT_ERR port events, and UNREGISTER triggers core 
unreg/dealloc.

My 2 centimes.


> Should the code handle other events such as NETDEV_CHANGEADDR?
>
>

This fires when a MAC address changes, yes?  Perhaps this should trigger a IB_EVENT_LID_CHANGE or something?  That would 
force the ib gid cache code to re-query your device for the updated MAC address  (see ib_cache_event() and friends). The 
chelsio drivers don't have this, but they probably need it.


Steve.
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