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Message-ID: <20071003150519.1fd206a8@freepuppy.rosehill>
Date: Wed, 3 Oct 2007 15:05:19 -0700
From: Stephen Hemminger <shemminger@...ux-foundation.org>
To: David Miller <davem@...emloft.net>
Cc: a.p.zijlstra@...llo.nl, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, jdike@...toit.com
Subject: Re: [PATCH] net: fix race in process_backlog
On Wed, 03 Oct 2007 14:58:07 -0700 (PDT)
David Miller <davem@...emloft.net> wrote:
> From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Date: Wed, 03 Oct 2007 17:44:53 +0200
>
> > Index: linux-2.6/net/core/dev.c
> > ===================================================================
> > --- linux-2.6.orig/net/core/dev.c
> > +++ linux-2.6/net/core/dev.c
> > @@ -2095,11 +2095,11 @@ static int process_backlog(struct napi_s
> >
> > local_irq_disable();
> > skb = __skb_dequeue(&queue->input_pkt_queue);
> > - local_irq_enable();
> > if (!skb) {
> > - napi_complete(napi);
> > + __napi_complete(napi);
> > break;
> > }
> > + local_irq_enable();
>
> What re-enables interrupts in the !skb path?
This looks like a better fix. the irq_enable is needed in both cases.
--- a/net/core/dev.c 2007-09-27 07:19:10.000000000 -0700
+++ b/net/core/dev.c 2007-10-03 15:03:54.000000000 -0700
@@ -2077,12 +2077,14 @@ static int process_backlog(struct napi_s
local_irq_disable();
skb = __skb_dequeue(&queue->input_pkt_queue);
- local_irq_enable();
if (!skb) {
- napi_complete(napi);
+ __napi_complete(napi);
+ local_irq_enable();
break;
}
+ local_irq_enable();
+
dev = skb->dev;
netif_receive_skb(skb);
--
Stephen Hemminger <shemminger@...ux-foundation.org>
-
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