On Wed, Jul 29, 2009 at 01:48:05PM -0700, Jeremy Fitzhardinge wrote:
> >>>>> The stack backtrace is a bit fuzzy; do you have CONFIG_FRAMEPOINTER 
> >>>>> enabled? 
> >>>>> And if you have CONFIG_DEBUGINFO enabled, you can map the eip c058cdcb 
> >>>>> to a specific source line (its not clear to me which pointer is NULL).
> >>>>>
> >>>>> 
> >>>>> 
> >>>> [root@dom0test linux-2.6-xen]# grep -i CONFIG_FRAMEPOINTER .config
> >>>> [root@dom0test linux-2.6-xen]# grep -i CONFIG_DEBUGINFO .config
> >>>> [root@dom0test linux-2.6-xen]# 
> >>>>
> >>>> Unfortunately those were not enabled.. I'll build a new kernel with
> >>>> CONFIG_DEBUGINFO enabled.
> >>>>
> >>>> 
> >>>> 
> >>> Actually CONFIG_DEBUG_INFO was enabled, if you meant that? 
> >>> 
> >>> 
> >> Yes, that's it.
> >> 
> >>> (gdb) x/i 0xc058cdcb
> >>> 
> >>> 
> >> Try "list *0xc058cdcb".
> >>
> >> 
> >
> > (gdb) list *0xc058cdcb
> > 0xc058cdcb is in active_evtchns (drivers/xen/events.c:237).
> > 232
> > 233 static inline unsigned long active_evtchns(unsigned int cpu,
> > 234 struct shared_info *sh,
> > 235 unsigned int idx)
> > 236 {
> > 237 return (sh->evtchn_pending[idx] &
> > 238 cpu_evtchn_mask(cpu)[idx] &
> > 239 ~sh->evtchn_mask[idx]);
> > 240 }
> > 241
> > (gdb)
> >
> >
> > -- Pasi
> >
> > 
>
> Does this help?
>
I'll try it later today. 
-- Pasi
> J
>
> Subject: [PATCH] xen: use proper percpu variable for cpu_evtchn_mask
>
> cpu_evtchn_mask is a per-cpu mask of event channels, so it should
> be implemented as a proper per_cpu variable.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
>
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index abad71b..4443b0f 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -93,14 +93,11 @@ static struct irq_info irq_info[NR_IRQS];
> static int evtchn_to_irq[NR_EVENT_CHANNELS] = {
> [0 ... NR_EVENT_CHANNELS-1] = -1
> };
> -struct cpu_evtchn_s {
> - unsigned long bits[NR_EVENT_CHANNELS/BITS_PER_LONG];
> -};
> -static struct cpu_evtchn_s *cpu_evtchn_mask_p;
> -static inline unsigned long *cpu_evtchn_mask(int cpu)
> -{
> - return cpu_evtchn_mask_p[cpu].bits;
> -}
> +
> +#define NR_EVENT_CHANNEL_LONGS (NR_EVENT_CHANNELS/BITS_PER_LONG)
> +static DEFINE_PER_CPU(unsigned long,
> + cpu_evtchn_mask[NR_EVENT_CHANNEL_LONGS]) =
> + {[0 ... NR_EVENT_CHANNEL_LONGS-1] = ~0};
>
> /* Xen will never allocate port zero for any purpose. */
> #define VALID_EVTCHN(chn) ((chn) != 0)
> @@ -223,7 +220,7 @@ static inline unsigned long active_evtchns(unsigned int 
> cpu,
> unsigned int idx)
> {
> return (sh->evtchn_pending[idx] &
> - cpu_evtchn_mask(cpu)[idx] &
> + per_cpu(cpu_evtchn_mask, cpu)[idx] &
> ~sh->evtchn_mask[idx]);
> }
>
> @@ -236,8 +233,8 @@ static void bind_evtchn_to_cpu(unsigned int chn, unsigned 
> int cpu)
> cpumask_copy(irq_to_desc(irq)->affinity, cpumask_of(cpu));
> #endif
>
> - __clear_bit(chn, cpu_evtchn_mask(cpu_from_irq(irq)));
> - __set_bit(chn, cpu_evtchn_mask(cpu));
> + __clear_bit(chn, per_cpu(cpu_evtchn_mask, cpu_from_irq(irq)));
> + __set_bit(chn, per_cpu(cpu_evtchn_mask, cpu));
>
> irq_info[irq].cpu = cpu;
> }
> @@ -253,8 +250,6 @@ static void init_evtchn_cpu_bindings(void)
> cpumask_copy(desc->affinity, cpumask_of(0));
> }
> #endif
> -
> - memset(cpu_evtchn_mask(0), ~0, sizeof(cpu_evtchn_mask(0)));
> }
>
> static inline void clear_evtchn(int port)
> @@ -928,10 +923,6 @@ void __init xen_init_IRQ(void)
> {
> int i;
>
> - cpu_evtchn_mask_p = kcalloc(nr_cpu_ids, sizeof(struct cpu_evtchn_s),
> - GFP_KERNEL);
> - BUG_ON(cpu_evtchn_mask_p == NULL);
> -
> init_evtchn_cpu_bindings();
>
> /* No event channels are 'live' right now. */
>
>
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