[PATCH] x86/irq: simplify loop in unmap_domain_pirq

[Roger Pau Monne <roger.pau@citrix.com>]

The for loop in unmap_domain_pirq is unnecessary complicated, with
several places where the index is incremented, and also different
exit conditions spread between the loop body.

Simplify it by looping over each possible PIRQ using the for loop
syntax, and remove all possible in-loop exit points.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/irq.c | 60 +++++++++++++---------------------------------
 1 file changed, 16 insertions(+), 44 deletions(-)

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 032fe82167..856714b5bf 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -2305,7 +2305,6 @@ done:
 /* The pirq should have been unbound before this call. */
 int unmap_domain_pirq(struct domain *d, int pirq)
 {
-    unsigned long flags;
     struct irq_desc *desc;
     int irq, ret = 0, rc;
     unsigned int i, nr = 1;
@@ -2356,11 +2355,23 @@ int unmap_domain_pirq(struct domain *d, int pirq)
     if ( msi_desc != NULL )
         pci_disable_msi(msi_desc);
 
-    spin_lock_irqsave(&desc->lock, flags);
-
-    for ( i = 0; ; )
+    for ( i = 0; i < nr; i++, info = pirq_info(d, pirq + i) )
     {
+        unsigned long flags;
+
+        if ( !info || info->arch.irq <= 0 )
+        {
+            printk(XENLOG_G_ERR "dom%d: MSI pirq %d not mapped\n",
+                   d->domain_id, pirq + i);
+            continue;
+        }
+        irq = info->arch.irq;
+        desc = irq_to_desc(irq);
+
+        spin_lock_irqsave(&desc->lock, flags);
+
         BUG_ON(irq != domain_pirq_to_irq(d, pirq + i));
+        BUG_ON(desc->msi_desc != msi_desc + i);
 
         if ( !forced_unbind )
             clear_domain_irq_pirq(d, irq, info);
@@ -2378,45 +2389,6 @@ int unmap_domain_pirq(struct domain *d, int pirq)
             desc->msi_desc = NULL;
         }
 
-        if ( ++i == nr )
-            break;
-
-        spin_unlock_irqrestore(&desc->lock, flags);
-
-        if ( !forced_unbind )
-           cleanup_domain_irq_pirq(d, irq, info);
-
-        rc = irq_deny_access(d, irq);
-        if ( rc )
-        {
-            printk(XENLOG_G_ERR
-                   "dom%d: could not deny access to IRQ%d (pirq %d)\n",
-                   d->domain_id, irq, pirq + i);
-            ret = rc;
-        }
-
-        do {
-            info = pirq_info(d, pirq + i);
-            if ( info && (irq = info->arch.irq) > 0 )
-                break;
-            printk(XENLOG_G_ERR "dom%d: MSI pirq %d not mapped\n",
-                   d->domain_id, pirq + i);
-        } while ( ++i < nr );
-
-        if ( i == nr )
-        {
-            desc = NULL;
-            break;
-        }
-
-        desc = irq_to_desc(irq);
-        BUG_ON(desc->msi_desc != msi_desc + i);
-
-        spin_lock_irqsave(&desc->lock, flags);
-    }
-
-    if ( desc )
-    {
         spin_unlock_irqrestore(&desc->lock, flags);
 
         if ( !forced_unbind )
@@ -2427,7 +2399,7 @@ int unmap_domain_pirq(struct domain *d, int pirq)
         {
             printk(XENLOG_G_ERR
                    "dom%d: could not deny access to IRQ%d (pirq %d)\n",
-                   d->domain_id, irq, pirq + nr - 1);
+                   d->domain_id, irq, pirq + i);
             ret = rc;
         }
     }
-- 
2.29.2