Re: [PATCH] BUG: using smp_processor_id() in preemptible[00000000] code: caller is __qdisc_run

From: David Miller
Date: Mon Aug 11 2008 - 17:00:29 EST


From: "John Kacur" <jkacur@xxxxxxxxx>
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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