linux-kernel - Re: [PATCH] BUG: using smp_processor_id() in preemptible [00000000] code: caller is __qdisc

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Message-Id: <20080811.140014.94581847.davem@davemloft.net>
Date:	Mon, 11 Aug 2008 14:00:14 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	jkacur@...il.com
Cc:	linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	mingo@...e.hu, tglx@...utronix.de, rostedt@...dmis.org,
	a.p.zijlstra@...llo.nl
Subject: Re: [PATCH] BUG: using smp_processor_id() in preemptible
 [00000000] code: caller is __qdisc_run

From: "John Kacur" <jkacur@...il.com>
Date: Mon, 11 Aug 2008 15:11:46 +0200

> __qdisc_run() calls qdisc_restart() which calls
> handle_dev_cpu_collision(skb, dev, q); and then the problem shows up
> here:
> __get_cpu_var(netdev_rx_stat).cpu_collision++;
> 
> The solution is to disable interrupts around the above increment. Here
> is an attached patch to do so. (Thank's to Peter Zijlstra for help in
> the analysis and dropping the answer in my lap, so if I got it right
> it is due to his help, but if I messed it up, then I did that part all
> by myself.)

__qdisc_run() always runs in software interrupt context,
so I guess this is some problem with the -rt stuff running
software interrupts in threads?
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