[PATCH v2 06/13] xen/arm: Avoid code duplication in find_unallocated_memory

[Luca Fancellu <luca.fancellu@xxxxxxx>]

The function find_unallocated_memory is using the same code to
loop through 3 structure of the same type, in order to avoid
code duplication, rework the code to have only one loop that
goes through all the structures.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
v2:
 - Add comment in the loop inside find_unallocated_memory to
   improve readability
v1:
 - new patch
---
---
 xen/arch/arm/domain_build.c | 70 +++++++++++++------------------------
 1 file changed, 25 insertions(+), 45 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 57cf92668ae6..269aaff4d067 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -869,12 +869,14 @@ static int __init add_ext_regions(unsigned long s_gfn, 
unsigned long e_gfn,
 static int __init find_unallocated_memory(const struct kernel_info *kinfo,
                                           struct membanks *ext_regions)
 {
-    const struct membanks *kinfo_mem = kernel_info_get_mem_const(kinfo);
-    const struct membanks *mem = bootinfo_get_mem();
-    const struct membanks *reserved_mem = bootinfo_get_reserved_mem();
+    const struct membanks *mem_banks[] = {
+        bootinfo_get_mem(),
+        kernel_info_get_mem_const(kinfo),
+        bootinfo_get_reserved_mem(),
+    };
     struct rangeset *unalloc_mem;
     paddr_t start, end;
-    unsigned int i;
+    unsigned int i, j;
     int res;
 
     dt_dprintk("Find unallocated memory for extended regions\n");
@@ -883,50 +885,28 @@ static int __init find_unallocated_memory(const struct 
kernel_info *kinfo,
     if ( !unalloc_mem )
         return -ENOMEM;
 
-    /* Start with all available RAM */
-    for ( i = 0; i < mem->nr_banks; i++ )
-    {
-        start = mem->bank[i].start;
-        end = mem->bank[i].start + mem->bank[i].size;
-        res = rangeset_add_range(unalloc_mem, PFN_DOWN(start),
-                                 PFN_DOWN(end - 1));
-        if ( res )
+    /*
+     * Exclude the following regions, in order:
+     * 1) Start with all available RAM
+     * 2) Remove RAM assigned to Dom0
+     * 3) Remove reserved memory
+     * The order comes from the initialization of the variable "mem_banks"
+     * above
+     */
+    for ( i = 0; i < ARRAY_SIZE(mem_banks); i++ )
+        for ( j = 0; j < mem_banks[i]->nr_banks; j++ )
         {
-            printk(XENLOG_ERR "Failed to add: %#"PRIpaddr"->%#"PRIpaddr"\n",
-                   start, end);
-            goto out;
-        }
-    }
-
-    /* Remove RAM assigned to Dom0 */
-    for ( i = 0; i < kinfo_mem->nr_banks; i++ )
-    {
-        start = kinfo_mem->bank[i].start;
-        end = kinfo_mem->bank[i].start + kinfo_mem->bank[i].size;
-        res = rangeset_remove_range(unalloc_mem, PFN_DOWN(start),
+            start = mem_banks[i]->bank[j].start;
+            end = mem_banks[i]->bank[j].start + mem_banks[i]->bank[j].size;
+            res = rangeset_add_range(unalloc_mem, PFN_DOWN(start),
                                     PFN_DOWN(end - 1));
-        if ( res )
-        {
-            printk(XENLOG_ERR "Failed to remove: %#"PRIpaddr"->%#"PRIpaddr"\n",
-                   start, end);
-            goto out;
-        }
-    }
-
-    /* Remove reserved-memory regions */
-    for ( i = 0; i < reserved_mem->nr_banks; i++ )
-    {
-        start = reserved_mem->bank[i].start;
-        end = reserved_mem->bank[i].start + reserved_mem->bank[i].size;
-        res = rangeset_remove_range(unalloc_mem, PFN_DOWN(start),
-                                    PFN_DOWN(end - 1));
-        if ( res )
-        {
-            printk(XENLOG_ERR "Failed to remove: %#"PRIpaddr"->%#"PRIpaddr"\n",
-                   start, end);
-            goto out;
+            if ( res )
+            {
+                printk(XENLOG_ERR "Failed to add: 
%#"PRIpaddr"->%#"PRIpaddr"\n",
+                    start, end);
+                goto out;
+            }
         }
-    }
 
     /* Remove grant table region */
     if ( kinfo->gnttab_size )
-- 
2.34.1