[Xen-devel] [PATCH 12/14] xen: events: remove use of nr_irqs as upper bound on number of pirqs

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

There isn't really much relationship between the two, other than
nr_irqs often being the larger of the two.

Allows us to remove a nr_irqs sized array, the only users of this
array are MSI setup and restore, neither of which are particularly
performance critical.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 drivers/xen/events.c |   59 +++++++++++++++++++++----------------------------
 1 files changed, 25 insertions(+), 34 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 002283e..6782251 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -107,8 +107,6 @@ struct irq_info
 #define PIRQ_NEEDS_EOI (1 << 0)
 #define PIRQ_SHAREABLE (1 << 1)
 
-static int *pirq_to_irq;
-
 static int *evtchn_to_irq;
 
 static DEFINE_PER_CPU(unsigned long [NR_EVENT_CHANNELS/BITS_PER_LONG],
@@ -196,8 +194,6 @@ static void xen_irq_info_pirq_init(unsigned irq,
        info->u.pirq.gsi = gsi;
        info->u.pirq.vector = vector;
        info->u.pirq.flags = flags;
-
-       pirq_to_irq[pirq] = irq;
 }
 
 /*
@@ -247,16 +243,6 @@ static unsigned pirq_from_irq(unsigned irq)
        return info->u.pirq.pirq;
 }
 
-static unsigned gsi_from_irq(unsigned irq)
-{
-       struct irq_info *info = info_for_irq(irq);
-
-       BUG_ON(info == NULL);
-       BUG_ON(info->type != IRQT_PIRQ);
-
-       return info->u.pirq.gsi;
-}
-
 static enum xen_irq_type type_from_irq(unsigned irq)
 {
        return info_for_irq(irq)->type;
@@ -653,12 +639,6 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
 
        spin_lock(&irq_mapping_update_lock);
 
-       if (pirq > nr_irqs) {
-               printk(KERN_WARNING "xen_map_pirq_gsi: pirq %d > nr_irqs %d!\n",
-                      pirq, nr_irqs);
-               goto out;
-       }
-
        irq = find_irq_by_gsi(gsi);
        if (irq != -1) {
                printk(KERN_INFO "xen_map_pirq_gsi: returning irq %d for gsi 
%u\n",
@@ -758,7 +738,6 @@ int xen_destroy_irq(int irq)
                        goto out;
                }
        }
-       pirq_to_irq[info->u.pirq.pirq] = -1;
 
        xen_free_irq(irq);
 
@@ -769,7 +748,24 @@ out:
 
 int xen_irq_from_pirq(unsigned pirq)
 {
-       return pirq_to_irq[pirq];
+       int irq;
+
+       struct irq_info *info;
+
+       spin_lock(&irq_mapping_update_lock);
+
+       list_for_each_entry(info, &xen_irq_list_head, list) {
+               if (info == NULL || info->type != IRQT_PIRQ)
+                       continue;
+               irq = info->irq;
+               if (info->u.pirq.pirq == pirq)
+                       goto out;
+       }
+       irq = -1;
+out:
+       spin_lock(&irq_mapping_update_lock);
+
+       return irq;
 }
 
 int bind_evtchn_to_irq(unsigned int evtchn)
@@ -1269,15 +1265,18 @@ static void restore_pirqs(void)
 {
        int pirq, rc, irq, gsi;
        struct physdev_map_pirq map_irq;
+       struct irq_info *info;
 
-       for (pirq = 0; pirq < nr_irqs; pirq++) {
-               irq = pirq_to_irq[pirq];
-               if (irq == -1)
+       list_for_each_entry(info, &xen_irq_list_head, list) {
+               if (info->type != IRQT_PIRQ)
                        continue;
 
+               pirq = info->u.pirq.pirq;
+               gsi = info->u.pirq.gsi;
+               irq = info->irq;
+
                /* save/restore of PT devices doesn't work, so at this point the
                 * only devices present are GSI based emulated devices */
-               gsi = gsi_from_irq(irq);
                if (!gsi)
                        continue;
 
@@ -1291,7 +1290,6 @@ static void restore_pirqs(void)
                        printk(KERN_WARNING "xen map irq failed gsi=%d irq=%d 
pirq=%d rc=%d\n",
                                        gsi, irq, pirq, rc);
                        xen_free_irq(irq);
-                       pirq_to_irq[pirq] = -1;
                        continue;
                }
 
@@ -1512,13 +1510,6 @@ void __init xen_init_IRQ(void)
 {
        int i;
 
-       /* We are using nr_irqs as the maximum number of pirq available but
-        * that number is actually chosen by Xen and we don't know exactly
-        * what it is. Be careful choosing high pirq numbers. */
-       pirq_to_irq = kcalloc(nr_irqs, sizeof(*pirq_to_irq), GFP_KERNEL);
-       for (i = 0; i < nr_irqs; i++)
-               pirq_to_irq[i] = -1;
-
        evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
                                    GFP_KERNEL);
        for (i = 0; i < NR_EVENT_CHANNELS; i++)
-- 
1.5.6.5


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