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

From: Herbert Xu
Date: Wed Mar 25 2009 - 23:41:52 EST


On Wed, Mar 25, 2009 at 08:20:50PM -0700, David Miller wrote:
>
> There is still a difference compared to your fix Herbert. Jarek's
> patch flushes GRO first before the unlink.
>
> I still believe that's critical, although like you I can't pinpoint
> why.
>
> I know that GRO ought to be disabled here, but what if for some reason
> it isn't? :-)

Sure, I can accept that somehow someone has enabled GRO :) But
I'd still like to know why flushing the GRO afterwards would
lead to a hang.

> Adam Richter has successfully tested Jarek's variant, and if Ingo's
> tests show that it makes his problem go away too then I'm definitely
> going with Jarek's patch.

I don't have a problem with that.

I've asked Adam to test my patch as well. So far the only failure
case against it has been on Ingo's machine, where the process_backlog
path isn't involved. Yes it's used for loopback, but he's seeing
the hang on eth0, which with that config uses netif_receive_skb
so it should continue to work even if process_backlog completely
seizes up.

Cheers,
--
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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