ACPI: use memory_read_from_buffer()

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/system.c b/drivers/acpi/system.c
index 769f248..5bd2dec 100644 (file)
--- a/drivers/acpi/system.c
+++ b/drivers/acpi/system.c
@@ -77,7 +77,6 @@ static ssize_t acpi_table_show(struct kobject *kobj,
            container_of(bin_attr, struct acpi_table_attr, attr);
        struct acpi_table_header *table_header = NULL;
        acpi_status status;
-       ssize_t ret_count = count;
 
        status =
            acpi_get_table(table_attr->name, table_attr->instance,
@@ -85,18 +84,8 @@ static ssize_t acpi_table_show(struct kobject *kobj,
        if (ACPI_FAILURE(status))
                return -ENODEV;
 
-       if (offset >= table_header->length) {
-               ret_count = 0;
-               goto end;
-       }
-
-       if (offset + ret_count > table_header->length)
-               ret_count = table_header->length - offset;
-
-       memcpy(buf, ((char *)table_header) + offset, ret_count);
-
-      end:
-       return ret_count;
+       return memory_read_from_buffer(buf, count, &offset,
+                                       table_header, table_header->length);
 }
 
 static void acpi_table_attr_init(struct acpi_table_attr *table_attr,