Re: WARNING: at net/core/dev.c:2161 net_rx_action()

[Jeff Garzik <jgarzik@pobox.com>]

Ingo Molnar wrote:
> * David Miller <davem@davemloft.net> wrote:
>
> > From: Ingo Molnar <mingo@elte.hu>
> > Date: Mon, 15 Oct 2007 13:24:30 +0200
> >
> > > got this warning with Linus' latest -git tree:
> > >
> > >   WARNING: at net/core/dev.c:2161 net_rx_action()
> > >    [<80564db4>] net_rx_action+0xce/0x186
> > >    [<8011ba98>] __do_softirq+0x6c/0xcf
> > >    [<8011bb2d>] do_softirq+0x32/0x36
> > >    [<8011bcae>] irq_exit+0x35/0x40
> > >    [<80104fdb>] do_IRQ+0x5c/0x71
> > >    [<801048cd>] do_nmi+0x8f/0x238
> > >    [<801033a3>] common_interrupt+0x23/0x30
> > >    =======================
> > This is a driver bug, the work "budget" passed into a driver's 
> > ->poll() handler should never be exceeded.  That's what this warning 
> > assertion is checking.
> >
> > What ethernet card is in your system and what driver is being used to 
> > drive it?
>
> it's forcedeth.
>
> i've checked nv_napi_poll(), and i dont see how it could return larger 
> than 'limit' number of packets.
>
> it could return packets == limit though:
>
>                 pkts = nv_rx_process_optimized(dev, budget);
> ...
>
>         if (pkts < budget) {
>                 /* re-enable receive interrupts */
>                 spin_lock_irqsave(&np->lock, flags);
>
>                 __netif_rx_complete(dev, napi);
>
> ...
>         return pkts;

FWIW, forcedeth has this funky disable_irq()-based locking mechanism 
that is currently the subject of some kernel.org bugzillas.  I would 
also check and make sure that isn't perturbing your results (even though 
it seems unrelated, based on what I read here).  That might include 
disabling MSI if it's enabled, and/or turning on spinlock debugging.

	Jeff




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