Re: [Bugme-new] [Bug 10326] New: inconsistent lock state in net_rx_action

[Jarek Poplawski <jarkao2@gmail.com>]

On Wed, Mar 26, 2008 at 05:14:03PM -0700, Andrew Morton wrote:
...
> > >> http://bugzilla.kernel.org/show_bug.cgi?id=10326
...
> No, it's not an irq_disable() thing, directly.
> 
> What lockdep is saying is that sky2_poll() is taking napi->poll_lock for
> writing with softirqs enabled, but net_rx_action() takes the same lock from
> within softirq context.
> 
> If sky2_poll() always takes napi->poll_lock under local_irq_disable() then
> that would be a lockdep bug.

sky2_poll() doesn't take napi->poll_lock; this lock is taken by
netpoll_poll() before calling sky2_poll(). And before this hardirqs
are disabled in write_msg(). So, theoretically lockdep could be right
if sky2_poll() would enable irqs after this. (If it were done in
netpoll - lockdep should warn before or after sky2_poll() call.)
But I really can't see any such possibility in sky2_poll().

Regards,
Jarek P.