acpi: remove final __acpi_map_table mapping before setting acpi_gbl_permanent_mmap

On x86, __acpi_map_table uses early_ioremap() to create the mapping,
replacing the previous mapping with a new one.  Once enough of the
kernel is up an running it switches to using normal ioremap().  At
that point, we need to clean up the final mapping to avoid a warning
from the early_ioremap subsystem.

This can be removed after all the instances in the ACPI code are fixed
that rely on early-ioremap's implicit overmapping of previously
mapped tables.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: NLen Brown <len.brown@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/acpi/boot.c

@@ -124,12 +124,14 @@ char *__init __acpi_map_table(unsigned long phys, unsigned long size)
 	static char *prev_map;
 	static unsigned long prev_size;
 
+	if (prev_map) {
+		early_iounmap(prev_map, prev_size);
+		prev_map = NULL;
+	}
+
 	if (!phys || !size)
 		return NULL;
 
-	if (prev_map)
-		early_iounmap(prev_map, prev_size);
-
 	prev_size = size;
 	prev_map = early_ioremap(phys, size);
 

drivers/acpi/bus.c

@@ -694,6 +694,12 @@ void __init acpi_early_init(void)
 	if (!acpi_strict)
 		acpi_gbl_enable_interpreter_slack = TRUE;
 
+	/*
+	 * Doing a zero-sized mapping will clear out the previous
+	 * __acpi_map_table() mapping, if any.
+	 */
+	__acpi_map_table(0, 0);
+
 	acpi_gbl_permanent_mmap = 1;
 
 	status = acpi_reallocate_root_table();