netdev - Re: [PATCH RFC] gianfar: Make polling safe with IRQs disabled

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Date:	Thu, 5 Nov 2009 17:20:28 +0300
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Jon Loeliger <jdl@....com>
Cc:	David Miller <davem@...emloft.net>, linuxppc-dev@...abs.org,
	netdev@...r.kernel.org, Andy Fleming <afleming@...escale.com>,
	Jason Wessel <jason.wessel@...driver.com>
Subject: Re: [PATCH RFC] gianfar: Make polling safe with IRQs disabled

On Thu, Nov 05, 2009 at 08:01:10AM -0600, Jon Loeliger wrote:
> > When using KGDBoE, gianfar driver spits 'Interrupt problem' messages,
> > which appears to be a legitimate warning, i.e. we may end up calling
> > netif_receive_skb() or vlan_hwaccel_receive_skb() with IRQs disabled.
> > 
> > This patch reworks the RX path so that if netpoll is enabled (the
> > only case when the driver don't know from what context the polling
> > may be called), we check whether IRQs are disabled, and if so we
> > fall back to safe variants of skb receiving functions.
> > 
> > Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
> > ---
> > 
> > I'm not sure if this is suitable for mainline since it doesn't
> > have KGDBoE support. Jason, if the patch is OK, would you like
> > to merge it into KGDB tree?
> 
> It's a legitimate problem with or without KGDBoE.  I see it
> occasionally when conn_track is enabled as well, for example.

Hm, then I'd better remove the #ifdef CONFIG_NETPOLL.

Interestingly though, why conn_track does the polling with irqs
disabled, could be a bug in the conn_track? Because pretty much
drivers assume that polling is called with IRQs enabled.

If it's easily reproducible, could you replace the printk() with
WARN_ON(1) and post the backtrace? Or I can try to reproduce the
issue if you tell me how.

Thanks!

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
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