xen: Fold exit paths in find_text_region()

Despite rcu_read_unlock() being fully inlineable, the optimiser doesn't appear
willing to fold the exit paths.  Rework the logic to do so explicitly.

This compiles to marginally better code in all cases.  No functional change.

Signed-off-by: Andrew Cooper <[email protected]>
Acked-by: Jan Beulich <[email protected]>

xen/common/virtual_region.c

@@ -40,20 +40,20 @@ static DEFINE_RCU_READ_LOCK(rcu_virtual_region_lock);
 
 const struct virtual_region *find_text_region(unsigned long addr)
 {
-    const struct virtual_region *region;
+    const struct virtual_region *iter, *region = NULL;
 
     rcu_read_lock(&rcu_virtual_region_lock);
-    list_for_each_entry_rcu( region, &virtual_region_list, list )
+    list_for_each_entry_rcu ( iter, &virtual_region_list, list )
     {
-        if ( (void *)addr >= region->start && (void *)addr < region->end )
+        if ( (void *)addr >= iter->start && (void *)addr < iter->end )
         {
-            rcu_read_unlock(&rcu_virtual_region_lock);
-            return region;
+            region = iter;
+            break;
         }
     }
     rcu_read_unlock(&rcu_virtual_region_lock);
 
-    return NULL;
+    return region;
 }
 
 void register_virtual_region(struct virtual_region *r)