RE: [PATCH] acpi: set return value to const char for some functions

[Moore, Robert]

In ACPICA, we tend to be very careful concerning the "const" keyword in order to avoid a phenomenon known as "const pollution".

That is not to say that we won't use const in some limited cases.

Bob


> -----Original Message-----
> From: LABBE Corentin [mailto:clabbe.montjoie@xxxxxxxxx]
> Sent: Wednesday, October 14, 2015 12:07 PM
> To: Moore, Robert; Zheng, Lv; Wysocki, Rafael J; lenb@xxxxxxxxxx
> Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; LABBE Corentin
> Subject: [PATCH] acpi: set return value to const char for some functions
> 
> This patch set some array of const char as const.
> In the same time, some function return pointer to thoses array without
> properly giving the information that the data is const.
> This patch set the return type of thoses functions as const char *
> 
> Signed-off-by: LABBE Corentin <clabbe.montjoie@xxxxxxxxx>
> ---
>  drivers/acpi/acpica/acutils.h  | 12 ++++++------
> drivers/acpi/acpica/utdecode.c | 24 ++++++++++++------------
>  drivers/acpi/acpica/uthex.c    |  4 ++--
>  drivers/acpi/tables.c          |  6 ++++--
>  4 files changed, 24 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/acpi/acpica/acutils.h b/drivers/acpi/acpica/acutils.h
> index fb2aa50..e5d9d4f 100644
> --- a/drivers/acpi/acpica/acutils.h
> +++ b/drivers/acpi/acpica/acutils.h
> @@ -189,21 +189,21 @@ char *acpi_ut_get_mutex_name(u32 mutex_id);  const
> char *acpi_ut_get_notify_name(u32 notify_value, acpi_object_type type);
> #endif
> 
> -char *acpi_ut_get_type_name(acpi_object_type type);
> +const char *acpi_ut_get_type_name(acpi_object_type type);
> 
>  char *acpi_ut_get_node_name(void *object);
> 
> -char *acpi_ut_get_descriptor_name(void *object);
> +const char *acpi_ut_get_descriptor_name(void *object);
> 
>  const char *acpi_ut_get_reference_name(union acpi_operand_object
> *object);
> 
> -char *acpi_ut_get_object_type_name(union acpi_operand_object *obj_desc);
> +const char *acpi_ut_get_object_type_name(union acpi_operand_object
> +*obj_desc);
> 
> -char *acpi_ut_get_region_name(u8 space_id);
> +const char *acpi_ut_get_region_name(u8 space_id);
> 
> -char *acpi_ut_get_event_name(u32 event_id);
> +const char *acpi_ut_get_event_name(u32 event_id);
> 
> -char acpi_ut_hex_to_ascii_char(u64 integer, u32 position);
> +const char acpi_ut_hex_to_ascii_char(u64 integer, u32 position);
> 
>  u8 acpi_ut_ascii_char_to_hex(int hex_char);
> 
> diff --git a/drivers/acpi/acpica/utdecode.c
> b/drivers/acpi/acpica/utdecode.c index 988e23b..e08cdb1 100644
> --- a/drivers/acpi/acpica/utdecode.c
> +++ b/drivers/acpi/acpica/utdecode.c
> @@ -114,7 +114,7 @@ const char
> *acpi_gbl_region_types[ACPI_NUM_PREDEFINED_REGIONS] = {
>  	"PCC"			/* 0x0A */
>  };
> 
> -char *acpi_ut_get_region_name(u8 space_id)
> +const char *acpi_ut_get_region_name(u8 space_id)
>  {
> 
>  	if (space_id >= ACPI_USER_REGION_BEGIN) { @@ -127,7 +127,7 @@ char
> *acpi_ut_get_region_name(u8 space_id)
>  		return ("InvalidSpaceId");
>  	}
> 
> -	return (ACPI_CAST_PTR(char, acpi_gbl_region_types[space_id]));
> +	return (ACPI_CAST_PTR(const char, acpi_gbl_region_types[space_id]));
>  }
> 
> 
> /*************************************************************************
> ******
> @@ -152,14 +152,14 @@ static const char
> *acpi_gbl_event_types[ACPI_NUM_FIXED_EVENTS] = {
>  	"RealTimeClock",
>  };
> 
> -char *acpi_ut_get_event_name(u32 event_id)
> +const char *acpi_ut_get_event_name(u32 event_id)
>  {
> 
>  	if (event_id > ACPI_EVENT_MAX) {
>  		return ("InvalidEventID");
>  	}
> 
> -	return (ACPI_CAST_PTR(char, acpi_gbl_event_types[event_id]));
> +	return (ACPI_CAST_PTR(const char, acpi_gbl_event_types[event_id]));
>  }
> 
> 
> /*************************************************************************
> ******
> @@ -220,17 +220,17 @@ static const char *acpi_gbl_ns_type_names[] = {
>  	/* 30 */ "Invalid"
>  };
> 
> -char *acpi_ut_get_type_name(acpi_object_type type)
> +const char *acpi_ut_get_type_name(acpi_object_type type)
>  {
> 
>  	if (type > ACPI_TYPE_INVALID) {
> -		return (ACPI_CAST_PTR(char, acpi_gbl_bad_type));
> +		return (ACPI_CAST_PTR(const char, acpi_gbl_bad_type));
>  	}
> 
> -	return (ACPI_CAST_PTR(char, acpi_gbl_ns_type_names[type]));
> +	return (ACPI_CAST_PTR(const char, acpi_gbl_ns_type_names[type]));
>  }
> 
> -char *acpi_ut_get_object_type_name(union acpi_operand_object *obj_desc)
> +const char *acpi_ut_get_object_type_name(union acpi_operand_object
> +*obj_desc)
>  {
> 
>  	if (!obj_desc) {
> @@ -318,7 +318,7 @@ static const char *acpi_gbl_desc_type_names[] = {
>  	/* 15 */ "Node"
>  };
> 
> -char *acpi_ut_get_descriptor_name(void *object)
> +const char *acpi_ut_get_descriptor_name(void *object)
>  {
> 
>  	if (!object) {
> @@ -329,7 +329,7 @@ char *acpi_ut_get_descriptor_name(void *object)
>  		return ("Not a Descriptor");
>  	}
> 
> -	return (ACPI_CAST_PTR(char,
> +	return (ACPI_CAST_PTR(const char,
>  			      acpi_gbl_desc_type_names[ACPI_GET_DESCRIPTOR_TYPE
>  						       (object)]));
> 
> @@ -400,7 +400,7 @@ const char *acpi_ut_get_reference_name(union
> acpi_operand_object *object)
> 
>  /* Names for internal mutex objects, used for debug output */
> 
> -static char *acpi_gbl_mutex_names[ACPI_NUM_MUTEX] = {
> +static const char *acpi_gbl_mutex_names[ACPI_NUM_MUTEX] = {
>  	"ACPI_MTX_Interpreter",
>  	"ACPI_MTX_Namespace",
>  	"ACPI_MTX_Tables",
> @@ -411,7 +411,7 @@ static char *acpi_gbl_mutex_names[ACPI_NUM_MUTEX] = {
>  	"ACPI_MTX_CommandReady"
>  };
> 
> -char *acpi_ut_get_mutex_name(u32 mutex_id)
> +const char *acpi_ut_get_mutex_name(u32 mutex_id)
>  {
> 
>  	if (mutex_id > ACPI_MAX_MUTEX) {
> diff --git a/drivers/acpi/acpica/uthex.c b/drivers/acpi/acpica/uthex.c
> index fda8b3d..9239711 100644
> --- a/drivers/acpi/acpica/uthex.c
> +++ b/drivers/acpi/acpica/uthex.c
> @@ -48,7 +48,7 @@
>  ACPI_MODULE_NAME("uthex")
> 
>  /* Hex to ASCII conversion table */
> -static char acpi_gbl_hex_to_ascii[] = {
> +static const char acpi_gbl_hex_to_ascii[] = {
>  	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C',
> 'D',
>  	    'E', 'F'
>  };
> @@ -67,7 +67,7 @@ static char acpi_gbl_hex_to_ascii[] = {
>   *
> 
> **************************************************************************
> ****/
> 
> -char acpi_ut_hex_to_ascii_char(u64 integer, u32 position)
> +const char acpi_ut_hex_to_ascii_char(u64 integer, u32 position)
>  {
> 
>  	return (acpi_gbl_hex_to_ascii[(integer >> position) & 0xF]); diff --
> git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index 17a6fa0..7c8a037
> 100644
> --- a/drivers/acpi/tables.c
> +++ b/drivers/acpi/tables.c
> @@ -35,8 +35,10 @@
> 
>  #define ACPI_MAX_TABLES		128
> 
> -static char *mps_inti_flags_polarity[] = { "dfl", "high", "res", "low" };
> -static char *mps_inti_flags_trigger[] = { "dfl", "edge", "res", "level"
> };
> +static const char * const mps_inti_flags_polarity[] = {
> +	"dfl", "high", "res", "low" };
> +static const char * const mps_inti_flags_trigger[] = {
> +	"dfl", "edge", "res", "level" };
> 
>  static struct acpi_table_desc initial_tables[ACPI_MAX_TABLES] __initdata;
> 
> --
> 2.4.9

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