ACPI / sysfs: Set file size for each exposed ACPI table

Currently, each of the ACPI tables exported from
/sys/firmware/acpi/tables is of zero size:

$ LANG=C ls -ld /sys/firmware/acpi/tables/*
-r-------- 1 root root 0 Nov 19 09:48 /sys/firmware/acpi/tables/APIC
-r-------- 1 root root 0 Nov 19 09:48 /sys/firmware/acpi/tables/BOOT
-r-------- 1 root root 0 Nov 19 14:25 /sys/firmware/acpi/tables/DSDT
-r-------- 1 root root 0 Nov 19 14:25 /sys/firmware/acpi/tables/FACP
-r-------- 1 root root 0 Nov 19 14:25 /sys/firmware/acpi/tables/FACS
-r-------- 1 root root 0 Nov 19 14:25 /sys/firmware/acpi/tables/MCFG
-r-------- 1 root root 0 Nov 19 14:25 /sys/firmware/acpi/tables/SRAT
drwxr-xr-x 2 root root 0 Nov 19 09:48 /sys/firmware/acpi/tables/dynamic/

due to which, user-land tools fail reading each table. For example:

$ acpidump -f /sys/firmware/acpi/tables/SRAT
Could not get input file size: /sys/firmware/acpi/tables/SRAT

To deal with the issue, this patch assigns size of each ACPI table to
the corresponding sysfs file.

$ LANG=C ls -hld /sys/firmware/acpi/tables/*
-r-------- 1 root root  94 Nov 19 16:45 /sys/firmware/acpi/tables/APIC
-r-------- 1 root root  40 Nov 19 16:45 /sys/firmware/acpi/tables/BOOT
-r-------- 1 root root 58K Nov 19 16:55 /sys/firmware/acpi/tables/DSDT
-r-------- 1 root root 244 Nov 19 16:55 /sys/firmware/acpi/tables/FACP
-r-------- 1 root root  64 Nov 19 16:55 /sys/firmware/acpi/tables/FACS
-r-------- 1 root root  60 Nov 19 16:55 /sys/firmware/acpi/tables/MCFG
-r-------- 1 root root 168 Nov 19 16:45 /sys/firmware/acpi/tables/SRAT
drwxr-xr-x 2 root root   0 Nov 19 16:55 /sys/firmware/acpi/tables/dynamic/

Then, user-land tools work well like:

$ acpidump -f /sys/firmware/acpi/tables/SRAT
SRAT @ 0x0000000000000000
  0000: 53 52 41 54 A8 00 00 00 02 65 56 4D 57 41 52 45  SRAT.....eVMWARE
  0010: 4D 45 4D 50 4C 55 47 20 00 00 04 06 56 4D 57 20  MEMPLUG ....VMW
  0020: 01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
  0030: 01 28 00 00 00 00 00 00 00 00 00 00 00 00 00 00  .(..............
  0040: 00 00 0A 00 00 00 00 00 00 00 00 00 01 00 00 00  ................
  0050: 00 00 00 00 00 00 00 00 01 28 00 00 00 00 00 00  .........(......
  0060: 00 00 10 00 00 00 00 00 00 00 F0 BF 00 00 00 00  ................
  0070: 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
  0080: 01 28 00 00 00 00 00 00 00 00 00 00 01 00 00 00  .(..............
  0090: 00 00 00 40 00 00 00 00 00 00 00 00 01 00 00 00  ...@............
  00A0: 00 00 00 00 00 00 00 00                          ........

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sysfs.c

@@ -309,7 +309,7 @@ static void acpi_table_attr_init(struct acpi_table_attr *table_attr,
 		sprintf(table_attr->name + ACPI_NAME_SIZE, "%d",
 			table_attr->instance);
 
-	table_attr->attr.size = 0;
+	table_attr->attr.size = table_header->length;
 	table_attr->attr.read = acpi_table_show;
 	table_attr->attr.attr.name = table_attr->name;
 	table_attr->attr.attr.mode = 0400;