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SubjectRe: [PATCH 0/4] atl1: Revised Attansic L1 ethernet driver
Alan wrote:
> Would be nice if it used atl_ not at_ so its less likely to cause
> namespace clashes.

Some of this code looked like Attansic may have meant to share it
between drivers for atl1/atl2/atf1/atf2, but seeing as I can't find any
code for those, I'll convert it all to atl1_ and let Attansic generalize
the code if they ever decide they want to submit drivers.

> You have various macros for swaps that are pretty ugly - we have
> cpu_to and le/be_to_cpu functions for most swapping cases and these are
> generally optimised assembler (eg bswap on x86)
>
> AT_DESC_USED/UNUSED would be better as inline functions but thats not a
> serious concern.
>
> Be careful with :1 bitfields when working with hardware - the compiler
> has more than one choice about how to pack them.

Lacking a spec, I'm not entirely sure what the original intent was, so
we're stuck with testing. Is there a specific disambiguation technique
you recommend?

> The irq enable/disable use for locking on vlan appears unsafe. PCI
> interrupt delivery is asynchronous which means you can get this happen
>
>
> card sends PCI interrupt
> We call irq_disable
> We take lock
> We poke bits
> We drop lock
>
> PCI interrupt arrives
>
>
> This really does happen, typically its nasty to debug as well because you
> usually only get it on PIII boards on the one in n-zillion times a
> message collides and is retransmitted on the APIC bus.

Nice catch. I admit the VLAN code is not so well audited or tested.
Fortunately, the chip only seems to be on Asus M2V motherboards, at
least for now, but I want to audit all of the locking code at some point.

> skb->len is unsigned so <= 0 can be == 0. More importantly the subtraction
> before the test will wrap and is completely unsafe (see at_xmit_frame)

Thanks!

-- Chris
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