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Re: Fw: [Bugme-new] [Bug 4628] New: Test server hang while running rhr (

To: akpm@xxxxxxxx (Andrew Morton)
Subject: Re: Fw: [Bugme-new] [Bug 4628] New: Test server hang while running rhr (network) test on RHEL4 with kernel 2.6.12-rc1-mm4
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 16 May 2005 21:00:50 +1000
Cc: netdev@xxxxxxxxxxx, hejianj@xxxxxxxxxx, linuxppc64-dev@xxxxxxxxxxxxxxxxxxxxxxxxxx, anton@xxxxxxxxx, jgarzik@xxxxxxxxx
In-reply-to: <20050516025901.4b26ccf3.akpm@xxxxxxxx>
Organization: Core
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: tin/1.7.4-20040225 ("Benbecula") (UNIX) (Linux/2.4.27-hx-1-686-smp (i686))
Andrew Morton <akpm@xxxxxxxx> wrote:
> 
> Might be a bug in the e100 driver, might not be.
> 
> I assume this is the
> 
>        BUG_ON(skb->list != NULL);

It certainly is a bug in e100.

e100_tx_timeout -> e100_down -> e100_rx_clean_list

is racing against

e100_poll -> e100_rx_clean -> e100_rx_indicate

e100_rx_clean/e100_rx_indicate takes an skb off the RX ring and
while it's being processed e100_rx_clean_list comes along and
frees it.

From a quick check similar problems may exist in other drivers that
have lockless ->poll() functions with RX rings.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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