linux-kernel - Re: [patch] net, 8139too.c: fix netpoll deadlock

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Message-Id: <20070214.113025.126141881.nemoto@toshiba-tops.co.jp>
Date:	Wed, 14 Feb 2007 11:30:25 +0900 (JST)
From:	Atsushi Nemoto <anemo@....ocn.ne.jp>
To:	mingo@...e.hu
Cc:	romieu@...zoreil.com, jeff@...zik.org, torvalds@...l.org,
	akpm@...l.org, davem@...emloft.net, tglx@...utronix.de,
	linux-kernel@...r.kernel.org
Subject: Re: [patch] net, 8139too.c: fix netpoll deadlock

Let me resume two months old topic...

On Wed, 13 Dec 2006 02:12:31 +0100, Ingo Molnar <mingo@...e.hu> wrote:
> > I have lived with the "NAPI ->poll() handler runs in BH irq enabled 
> > context" rule for years. Is it definitely false/dead ?
> > 
> > If so at least 8139cp needs the same fix.
> 
> hm, this isnt really about NAPI polling, but about the 
> netconsole/netpoll/netdump poll_controller() handler.
> 
> with netconsole, printk can be called from IRQ context (and is 
> frequently from IRQ context during bootup or module initialization), so 
> a BH rule isnt enough for them.

I see NAPI poll routine might be called with interrupt disabled.

Many (all?) NAPI drivers call netif_receive_skb() from its poll
routine (as described in NAPI-HOWTO.txt), but I thought
netif_receive_skb() cannot be called from irq context or irq disabled.
So it seems the problem is not solved completely.  Or am I missing
something?

---
Atsushi Nemoto
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