Re: Revert "gro: Fix legacy path napi_complete crash",

David Miller
2009-03-25T02:09:39Z

From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Wed, 25 Mar 2009 08:32:35 +0800

> On Tue, Mar 24, 2009 at 05:02:41PM +0100, Ingo Molnar wrote:
> >
> > * Herbert Xu <herbert@gondor.apana.org.au> wrote:
> >
> > > What's the NIC and config on this one? If it's still using the
> > > legacy/netif_rx path, where GRO is off by default, this patch
> > > should make it exactly the same as with my original patch
> > > reverted.
> >
> > Same forcedeth box i reported before. Config below. (note: if you
> > want to use it you need to run it through 'make oldconfig', with all
> > defaults accepted)
> >
> > CONFIG_FORCEDETH=y
> > CONFIG_FORCEDETH_NAPI=y
>
> This means that we shouldn't even invoke netif_rx/process_backlog,
> so something else is going on.

There is always loopback which does netif_rx().

Combine that with the straight NAPI receive that forcedeth
is doing here and I'm sure there are all kinds of race
scenerios possible :-)

You're right about GRO not being relevant here. To be honest
I wouldn't be disappointed if GRO was simply on by default
even for the legacy paths.