Re: [PATCH,try2 1/3] ep93xx_eth: fix RX/TXstatus ring full handling

[Jeff Garzik <jeff@garzik.org>]

Lennert Buytenhek wrote:
> Ray Lehtiniemi reported that an incoming UDP packet flood can lock up
> the ep93xx ethernet driver.  Herbert Valerio Riedel noted that due to
> the way ep93xx_eth manages the RX/TXstatus rings, it cannot distinguish
> a full ring from an empty one, and correctly suggested that this was
> likely to be causing this lockup to occur.
> 
> Instead of looking at the hardware's RX/TXstatus ring write pointers
> to determine when to stop reading from those rings, we should just check
> every individual RX/TXstatus descriptor's valid bit instead, since there
> is no other way to distinguish an empty ring from a full ring, and if
> there is a descriptor waiting, we take the hit of reading the descriptor
> from memory anyway.
> 
> Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>

applied 1-3