From f811f890ff549fe433091076da308a44b906f271 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com>
Date: Fri, 9 Apr 2021 09:20:57 +0200
Subject: [PATCH] x86/irq: simplify loop in unmap_domain_pirq
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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>
Reviewed-by: Jan Beulich <jbeulich@suse.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..a1693f92dd 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 "%pd: MSI pirq %d not mapped\n",
+                   d, 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;
         }
     }
-- 
2.30.2