netdev - Re: unsafe locks seen with netperf on net-2.6.29 tree

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Message-ID: <20081229103154.GA9691@gondor.apana.org.au>
Date:	Mon, 29 Dec 2008 21:31:54 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	"Tantilov, Emil S" <emil.s.tantilov@...el.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	netdev <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	"Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr@...el.com>,
	"Duyck, Alexander H" <alexander.h.duyck@...el.com>,
	Ingo Molnar <mingo@...e.hu>, Eric Dumazet <dada1@...mosbay.com>
Subject: Re: unsafe locks seen with netperf on net-2.6.29 tree

On Mon, Dec 29, 2008 at 11:02:07AM +0100, Peter Zijlstra wrote:
>
> Subject: net: fix tcp deadlock
> 
> Lockdep spotted that the percpu counter op takes a lock so that softirq
> recursion deadlocks can occur. Delay the op until we've disabled
> softirqs to avoid this.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>

You also need to patch the other places where we use that percpu
counter from process context, e.g., for /proc/net/tcp.

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