[PATCH v2] arm/irq: Reorder check when the IRQ is already used by someone

[Oleksandr Tyshchenko <olekstysh@gmail.com>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Call irq_get_domain for the IRQ we are interested in
only after making sure that it is the guest IRQ to avoid
ASSERT(test_bit(_IRQ_GUEST, &desc->status)) triggering.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Andrii Anisov <andrii_anisov@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien.grall@arm.com>
---
 xen/arch/arm/irq.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 06d4843..6d7e44e 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -477,26 +477,28 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
      */
     if ( desc->action != NULL )
     {
-        struct domain *ad = irq_get_domain(desc);
-
-        if ( test_bit(_IRQ_GUEST, &desc->status) && d == ad )
+        if ( test_bit(_IRQ_GUEST, &desc->status) )
         {
-            if ( irq_get_guest_info(desc)->virq != virq )
+            struct domain *ad = irq_get_domain(desc);
+
+            if ( d != ad )
+            {
+                printk(XENLOG_G_ERR "IRQ %u is already used by domain %u\n",
+                       irq, ad->domain_id);
+                retval = -EBUSY;
+            } else if ( irq_get_guest_info(desc)->virq != virq )
             {
                 printk(XENLOG_G_ERR
                        "d%u: IRQ %u is already assigned to vIRQ %u\n",
                        d->domain_id, irq, irq_get_guest_info(desc)->virq);
                 retval = -EBUSY;
             }
-            goto out;
         }
-
-        if ( test_bit(_IRQ_GUEST, &desc->status) )
-            printk(XENLOG_G_ERR "IRQ %u is already used by domain %u\n",
-                   irq, ad->domain_id);
         else
+        {
             printk(XENLOG_G_ERR "IRQ %u is already used by Xen\n", irq);
-        retval = -EBUSY;
+            retval = -EBUSY;
+        }
         goto out;
     }
 
-- 
2.7.4


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