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[Xen-devel] [PATCH 34 of 38] xen: remove irq bindcount

To: Ingo Molnar <mingo@xxxxxxx>
Subject: [Xen-devel] [PATCH 34 of 38] xen: remove irq bindcount
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Thu, 13 Nov 2008 11:10:32 -0800
Cc: the arch/x86 maintainers <x86@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Ian Campbell <ian.campbell@xxxxxxxxxx>
Delivery-date: Thu, 13 Nov 2008 11:56:06 -0800
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There should be no need for us to maintain our own bind count for
irqs, since the surrounding irq system should keep track of shared
irqs for us.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 drivers/xen/events.c |   26 +++++++-------------------
 1 file changed, 7 insertions(+), 19 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -53,7 +53,7 @@
 
 /* Interrupt types. */
 enum xen_irq_type {
-       IRQT_UNBOUND,
+       IRQT_UNBOUND = 0,
        IRQT_PIRQ,
        IRQT_VIRQ,
        IRQT_IPI,
@@ -94,9 +94,6 @@
 };
 static unsigned long cpu_evtchn_mask[NR_CPUS][NR_EVENT_CHANNELS/BITS_PER_LONG];
 
-/* Reference counts for bindings to IRQs. */
-static int irq_bindcount[NR_IRQS];
-
 /* Xen will never allocate port zero for any purpose. */
 #define VALID_EVTCHN(chn)      ((chn) != 0)
 
@@ -320,9 +317,8 @@
 {
        int irq;
 
-       /* Only allocate from dynirq range */
        for_each_irq_nr(irq)
-               if (irq_bindcount[irq] == 0)
+               if (irq_info[irq].type == IRQT_UNBOUND)
                        break;
 
        if (irq == nr_irqs)
@@ -351,8 +347,6 @@
                irq_info[irq] = mk_evtchn_info(evtchn);
        }
 
-       irq_bindcount[irq]++;
-
        spin_unlock(&irq_mapping_update_lock);
 
        return irq;
@@ -389,8 +383,6 @@
                bind_evtchn_to_cpu(evtchn, cpu);
        }
 
-       irq_bindcount[irq]++;
-
  out:
        spin_unlock(&irq_mapping_update_lock);
        return irq;
@@ -427,8 +419,6 @@
                bind_evtchn_to_cpu(evtchn, cpu);
        }
 
-       irq_bindcount[irq]++;
-
        spin_unlock(&irq_mapping_update_lock);
 
        return irq;
@@ -441,7 +431,7 @@
 
        spin_lock(&irq_mapping_update_lock);
 
-       if ((--irq_bindcount[irq] == 0) && VALID_EVTCHN(evtchn)) {
+       if (VALID_EVTCHN(evtchn)) {
                close.port = evtchn;
                if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
                        BUG();
@@ -667,6 +657,8 @@
 /* Rebind a new event channel to an existing irq. */
 void rebind_evtchn_irq(int evtchn, int irq)
 {
+       struct irq_info *info = info_for_irq(irq);
+
        /* Make sure the irq is masked, since the new event channel
           will also be masked. */
        disable_irq(irq);
@@ -676,8 +668,8 @@
        /* After resume the irq<->evtchn mappings are all cleared out */
        BUG_ON(evtchn_to_irq[evtchn] != -1);
        /* Expect irq to have been bound before,
-          so the bindcount should be non-0 */
-       BUG_ON(irq_bindcount[irq] == 0);
+          so there should be a proper type */
+       BUG_ON(info->type != IRQT_UNBOUND);
 
        evtchn_to_irq[evtchn] = irq;
        irq_info[irq] = mk_evtchn_info(evtchn);
@@ -930,9 +922,5 @@
        for (i = 0; i < NR_EVENT_CHANNELS; i++)
                mask_evtchn(i);
 
-       /* Dynamic IRQ space is currently unbound. Zero the refcnts. */
-       for_each_irq_nr(i)
-               irq_bindcount[i] = 0;
-
        irq_ctx_init(smp_processor_id());
 }



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