Re: [PATCH] trivial: remove ACPI_ARRAY_LENGTH macro.

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Sunday 01 November 2009 03:36:12 pm Thiago Farina wrote:
> Since the kernel already has a macro (ARRAY_SIZE) that does the same thing,
> just use it instead of defining another macro for the same propose.

This changes the ACPICA, which is used in several OSes besides Linux.
The CA is designed to have a small, controlled interface to the host OS.
This patch would expand that interface, which would work fine on Linux,
but would cause problems on other OSes that don't provide ARRAY_SIZE().

It'd be nice to have a little text in Documentation/acpi/ that covered
issues like this.  It could also talk about the special licensing
requirements for ACPICA changes.  And MAINTAINERS could mention it for
the path prefix "drivers/acpi/acpica/".

Bjorn

>  drivers/acpi/acpica/hwvalid.c |    2 +-
>  drivers/acpi/acpica/uteval.c  |    4 ++--
>  include/acpi/actypes.h        |    4 ----
>  3 files changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/acpi/acpica/hwvalid.c b/drivers/acpi/acpica/hwvalid.c
> index ec33f27..ca2eb02 100644
> --- a/drivers/acpi/acpica/hwvalid.c
> +++ b/drivers/acpi/acpica/hwvalid.c
> @@ -103,7 +103,7 @@ static const struct acpi_port_info acpi_protected_ports[] = {
>  	{"PCI", 0x0CF8, 0x0CFF, ACPI_OSI_WIN_XP}
>  };
>  
> -#define ACPI_PORT_INFO_ENTRIES  ACPI_ARRAY_LENGTH (acpi_protected_ports)
> +#define ACPI_PORT_INFO_ENTRIES  ARRAY_SIZE(acpi_protected_ports)
>  
>  /******************************************************************************
>   *
> diff --git a/drivers/acpi/acpica/uteval.c b/drivers/acpi/acpica/uteval.c
> index 5d54e36..54efbaa 100644
> --- a/drivers/acpi/acpica/uteval.c
> +++ b/drivers/acpi/acpica/uteval.c
> @@ -126,7 +126,7 @@ acpi_status acpi_ut_osi_implementation(struct acpi_walk_state *walk_state)
>  
>  	/* Compare input string to static table of supported interfaces */
>  
> -	for (i = 0; i < ACPI_ARRAY_LENGTH(acpi_interfaces_supported); i++) {
> +	for (i = 0; i < ARRAY_SIZE(acpi_interfaces_supported); i++) {
>  		if (!ACPI_STRCMP(string_desc->string.pointer,
>  				 acpi_interfaces_supported[i].name)) {
>  			/*
> @@ -186,7 +186,7 @@ acpi_status acpi_osi_invalidate(char *interface)
>  {
>  	int i;
>  
> -	for (i = 0; i < ACPI_ARRAY_LENGTH(acpi_interfaces_supported); i++) {
> +	for (i = 0; i < ARRAY_SIZE(acpi_interfaces_supported); i++) {
>  		if (!ACPI_STRCMP(interface, acpi_interfaces_supported[i].name)) {
>  			*acpi_interfaces_supported[i].name = '\0';
>  			return AE_OK;
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> index 153f12d..641d746 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -441,10 +441,6 @@ typedef unsigned long long acpi_integer;
>  #define ACPI_MIN(a,b)                   (((a)<(b))?(a):(b))
>  #define ACPI_MAX(a,b)                   (((a)>(b))?(a):(b))
>  
> -/* Size calculation */
> -
> -#define ACPI_ARRAY_LENGTH(x)            (sizeof(x) / sizeof((x)[0]))
> -
>  /* Pointer manipulation */
>  
>  #define ACPI_CAST_PTR(t, p)             ((t *) (acpi_uintptr_t) (p))