x86 boot: proper use of ARRAY_SIZE instead of repeated E820MAX constant

This patch is motivated by a subsequent patch which will allow for more
memory map entries on EFI supported systems than can be passed via the x86
legacy BIOS E820 interface.  The legacy interface is limited to E820MAX ==
128 memory entries, and that "E820MAX" manifest constant was used as the
size for several arrays and loops over those arrays.

The primary change in this patch is to change code loop sizes over those
arrays from using the constant E820MAX, to using the ARRAY_SIZE() macro
evaluated for the array being looped.  That way, a subsequent patch can
change the size of some of these arrays, without breaking this code.

This patch also adds a parameter to the sanitize_e820_map() routine,
which had an implicit size for the array passed it of E820MAX entries.
This new parameter explicitly passes the size of said array.  Once again,
this will allow a subsequent patch to change that array size for some
calls to sanitize_e820_map() without breaking the code.

As part of enhancing the sanitize_e820_map() interface this way, I further
combined the unnecessarily distinct x86_32 and x86_64 declarations for
this routine into a single, commonly used, declaration.

This patch in itself should make no difference to the resulting kernel
binary.

[ mingo@elte.hu: merged to -tip ]

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 4 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 2cb686f60d0..2396b9da802 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -95,7 +95,7 @@ void __init add_memory_region(u64 start, u64 size, int type)
 {
 	int x = e820.nr_map;
 
-	if (x == E820MAX) {
+	if (x == ARRAY_SIZE(e820.map)) {
 		printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
 		return;
 	}
@@ -142,7 +142,8 @@ void __init e820_print_map(char *who)
  * replaces the original e820 map with a new one, removing overlaps.
  *
  */
-int __init sanitize_e820_map(struct e820entry *biosmap, char *pnr_map)
+int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map,
+				char *pnr_map)
 {
 	struct change_member {
 		struct e820entry *pbios; /* pointer to original bios entry */
@@ -314,7 +315,7 @@ int __init sanitize_e820_map(struct e820entry *biosmap, char *pnr_map)
 					 * no more space left for new
 					 * bios entries ?
 					 */
-					if (++new_bios_entry >= E820MAX)
+					if (++new_bios_entry >= max_nr_map)
 						break;
 			}
 			if (current_type != 0)	{
@@ -403,7 +404,7 @@ void __init update_e820(void)
 	u8 nr_map;
 
 	nr_map = e820.nr_map;
-	if (sanitize_e820_map(e820.map, &nr_map))
+	if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &nr_map))
 		return;
 	e820.nr_map = nr_map;
 	printk(KERN_INFO "modified physical RAM map:\n");