Re: Revert "gro: Fix legacy path napi_complete crash", (was: Re: Linux 2.6.29)

Herbert Xu
2009-03-24T13:36:34Z

On Tue, Mar 24, 2009 at 02:02:02PM +0100, Ingo Molnar wrote:
>
> Yesterday about half of my testboxes (3 out of 7) started getting
> weird networking failures: their network interface just got stuck
> completely - no rx and no tx at all. Restarting the interface did
> not help.

Darn, does this patch help?

net: Fix netpoll lockup in legacy receive 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.

While this is fishy in itself, let's make the obvious fix right
now of reverting to the previous state where we always called
__napi_complete.

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

diff --git a/net/core/dev.c b/net/core/dev.c
index e3fe5c7..523f53e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2580,24 +2580,26 @@ static int process_backlog(struct napi_struct *napi, int quota)
int work = 0;
struct softnet_data *queue = &__get_cpu_var(softnet_data);
unsigned long start_time = jiffies;
+ struct sk_buff *skb;

napi->weight = weight_p;
do {
- struct sk_buff *skb;
-
local_irq_disable();
skb = __skb_dequeue(&queue->input_pkt_queue);
- if (!skb) {
- local_irq_enable();
- napi_complete(napi);
- goto out;
- }
local_irq_enable();
+ if (!skb)
+ break;

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

napi_gro_flush(napi);
+ if (skb)
+ goto out;
+
+ local_irq_disable();
+ __napi_complete(napi);
+ local_irq_enable();

out:
return work;

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