netdev - Re: net_rx_action/NAPI oops [PATCH]

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Date:	Tue, 27 Nov 2007 14:09:04 -0800
From:	Stephen Hemminger <shemminger@...ux-foundation.org>
To:	Robert Olsson <Robert.Olsson@...a.slu.se>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	Robert.Olsson@...a.slu.se, Auke Kok <sofar@...-projects.org>
Subject: Re: net_rx_action/NAPI oops [PATCH]

On Tue, 27 Nov 2007 19:52:24 +0100
Robert Olsson <Robert.Olsson@...a.slu.se> wrote:

> 
> Hello!
> 
> I've discovered a bug while testing the new multiQ NAPI code. In hi-load 
> situations when we take down an interface we get a kernel panic. The
> oops is below.
> 
> From what I see this happens when driver does napi_disable() and clears
> NAPI_STATE_SCHED. In net_rx_action there is a check for work == weight 
> a sort indirect test but that's now not enough to cover the load situation. 
> where we have NAPI_STATE_SCHED cleared by e1000_down in my case and still 
> full quota. Latest git but I'll guess the is the same in all later kernels.
> There might be different solutions... one variant is below:

It is considered a driver bug in 2.6.24 to call netif_rx_complete (clear NAPI_STATE_SCHED)
and do a full quota. That bug already had to be fixed in other drivers,
look like e1000 has same problem.


-- 
Stephen Hemminger <shemminger@...ux-foundation.org>
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