Re: [patch 4/10] s390: network driver.

[Jeff Garzik <jgarzik@xxxxxxxxx>]

Tommy Christensen wrote:
> Jeff Garzik wrote:
>
> > I haven't heard anything to convince me that the same change should be 
> > deployed across NNN drivers.  The drivers already signal the net core 
> > that the link is down; to me, that implies there should be code in 
> > _one_ place that handles this condition, not NNN places.
>
> AFAICS only a handful of (newer) drivers call netif_stop_queue() directly.
> Others may do this indirectly if the MAC stops taking packets from the
> DMA ringbuffer. At least some MAC's/drivers certainly don't.
Incorrect.  Use of netif_stop_queue() is -required- to signal that the 
hardware cannot accept any more skbs from the system.
Far more than a "handful" and required for all but a few very strange 
drivers.

> OK, another view on this: isn't is problematic to have skb's stuck in
> the network stack "indefinitely" ?
> They hold references to a dst_entry and a sock (and probably more).
> So how about this for the FAQ:
>  Q: Why can't I unload the af_packet module?
>  A: Ohh, you'll have to plug in the darn cable to eth0 first!
> *Please* tell me, I've got this all wrong.
You've got this all wrong.

        Jeff