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

Herbert Xu
2009-03-25T12:10:16Z

On Wed, Mar 25, 2009 at 08:33:49AM +0100, Ingo Molnar wrote:
>
> So if there's no definitive resolution for the real cause of the
> bug, the plain revert looks like an acceptable interim choice for
> .29.1 - at least as far as my systems go.

OK, let's just do the revert and disable GRO for the legacy path.
This should be the safest option for 2.6.29.

GRO: Disable GRO on legacy netif_rx path

When I fixed the GRO crash in the legacy receive path I used
napi_complete to replace __napi_complete. Unfortunately they're
not the same when NETPOLL is enabled, which may result in us
not calling __napi_complete at all.

What's more, we really do need to keep the __napi_complete call
within the IRQ-off section since in theory an IRQ can occur in
between and fill up the backlog to the maximum, causing us to
lock up.

Since we can't seem to find a fix that works properly right now,
this patch reverts all the GRO support from the netif_rx path.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/net/core/dev.c b/net/core/dev.c
index e3fe5c7..e438f54 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2588,18 +2588,15 @@ static int process_backlog(struct napi_struct *napi, int quota)
local_irq_disable();
skb = __skb_dequeue(&queue->input_pkt_queue);
if (!skb) {
+ __napi_complete(napi);
local_irq_enable();
- napi_complete(napi);
- goto out;
+ break;
}
local_irq_enable();

- napi_gro_receive(napi, skb);
+ netif_receive_skb(skb);
} while (++work < quota && jiffies == start_time);

- napi_gro_flush(napi);
-
-out:
return work;
}

Thanks,
--
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Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
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