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From: Marin Mitov <mitov@issp.bas.bg>
To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
       netdev@vger.kernel.org
Subject: Re: [patch for 2.6.25? 3/3] skge napi->poll() locking bug
Date: Thu, 27 Mar 2008 12:03:17 +0200
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On 27.3.2008, you wrote:
> From: Marin Mitov <mitov@issp.bas.bg>
> 
> According to: Documentation/networking/netdevices.txt:
> 
> <cite>
> napi->poll:
> ..........
> 	Context: softirq
> 	         will be called with interrupts disabled by netconsole.
> </cite>
> 
> napi->poll() could be called either with interrupts enabled
> (in softirq context) or disabled (by netconsole), so the irq flag
> should be preserved.
> 
> Inspired by Ingo's resent forcedeth patch :-)
> 
As far as skge driver has not changed since 2.6.24, the
patch could be applied to the stable 2.6.24.5 release too.

Marin Mitov

> Signed-off-by: Marin Mitov <mitov@issp.bas.bg>
> Acked-by: David S. Miller <davem@davemloft.net>
> Cc: Jeff Garzik <jeff@garzik.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  drivers/net/skge.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff -puN drivers/net/skge.c~skge-napi-poll-locking-bug drivers/net/skge.c
> --- a/drivers/net/skge.c~skge-napi-poll-locking-bug
> +++ a/drivers/net/skge.c
> @@ -3199,12 +3199,14 @@ static int skge_poll(struct napi_struct 
>  	skge_write8(hw, Q_ADDR(rxqaddr[skge->port], Q_CSR), CSR_START);
>  
>  	if (work_done < to_do) {
> -		spin_lock_irq(&hw->hw_lock);
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&hw->hw_lock, flags);
>  		__netif_rx_complete(dev, napi);
>  		hw->intr_mask |= napimask[skge->port];
>  		skge_write32(hw, B0_IMSK, hw->intr_mask);
>  		skge_read32(hw, B0_IMSK);
> -		spin_unlock_irq(&hw->hw_lock);
> +		spin_unlock_irqrestore(&hw->hw_lock, flags);
>  	}
>  
>  	return work_done;
> _
>