[PATCH] x86/boot: Move detecting acpi=off in cmdline to get_rsdp_addr()

[Chao Fan]

If "acpi=off" specified in cmdline, the whole functions of acpi.c
should not work, there is no need to ealy parse RSDP, so detect
"acpi=off" in the very first place.

Also replace magic number with macro.

Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/boot/compressed/acpi.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 0ef4ad55b29b..5510a2105b7b 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -213,8 +213,13 @@ static acpi_physical_address bios_get_rsdp_addr(void)
 /* Return RSDP address on success, otherwise 0. */
 acpi_physical_address get_rsdp_addr(void)
 {
+	char arg[MAX_ACPI_ARG_LENGTH];
 	acpi_physical_address pa;
 
+	if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
+	    !strncmp(arg, "off", 3))
+		return 0;
+
 	pa = get_acpi_rsdp();
 
 	if (!pa)
@@ -235,9 +240,9 @@ static unsigned long get_acpi_srat_table(void)
 {
 	unsigned long root_table, acpi_table;
 	struct acpi_table_header *header;
+	char arg[MAX_ACPI_ARG_LENGTH];
 	struct acpi_table_rsdp *rsdp;
 	u32 num_entries, size, len;
-	char arg[10];
 	u8 *entry;
 
 	rsdp = (struct acpi_table_rsdp *)(long)boot_params->acpi_rsdp_addr;
@@ -299,13 +304,8 @@ int count_immovable_mem_regions(void)
 	unsigned long table_addr, table_end, table;
 	struct acpi_subtable_header *sub_table;
 	struct acpi_table_header *table_header;
-	char arg[MAX_ACPI_ARG_LENGTH];
 	int num = 0;
 
-	if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
-	    !strncmp(arg, "off", 3))
-		return 0;
-
 	table_addr = get_acpi_srat_table();
 	if (!table_addr)
 		return 0;
-- 
2.20.1