Re: [PATCH][next] ACPICA: Use fallthrough pseudo-keyword

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

Hi,


This is a macro pseudo-keyword, which expands to /* fallthrough */
for compilers that don't support the attribute __fallthrough__. See:

include/linux/compiler_attributes.h:213:
213 #if __has_attribute(__fallthrough__)
214 # define fallthrough                    __attribute__((__fallthrough__))
215 #else
216 # define fallthrough                    do {} while (0)  /* fallthrough */
217 #endif

So, any compiler (older or new) will be fine with it.

Thanks
--
Gustavo

On 7/8/20 09:17, Moore, Robert wrote:
> It looks like this attribute is not supported by msvc 2017 (and perhaps other compilers) -- it is apparently a GCC extension -- meaning that it cannot be used in the ACPICA compiler-independent code.
> 
> Bob
> 
> 
> -----Original Message-----
> From: Rafael J. Wysocki <rafael@kernel.org> 
> Sent: Wednesday, July 08, 2020 3:59 AM
> To: Gustavo A. R. Silva <gustavoars@kernel.org>
> Cc: Moore, Robert <robert.moore@intel.com>; Kaneda, Erik <erik.kaneda@intel.com>; Wysocki, Rafael J <rafael.j.wysocki@intel.com>; Len Brown <lenb@kernel.org>; ACPI Devel Maling List <linux-acpi@vger.kernel.org>; open list:ACPI COMPONENT ARCHITECTURE (ACPICA) <devel@acpica.org>; Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
> Subject: Re: [PATCH][next] ACPICA: Use fallthrough pseudo-keyword
> 
> On Tue, Jul 7, 2020 at 10:01 PM Gustavo A. R. Silva <gustavoars@kernel.org> wrote:
>>
>> Replace the existing /* fall through */ comments and its variants with 
>> the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary 
>> fall-through markings when it is the case.
>>
>> [1] 
>> https://www.kernel.org/doc/html/latest/process/deprecated.html?highlig
>> ht=fallthrough#implicit-switch-case-fall-through
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> 
> I need to talk to Erik and Bob about this one.
> 
>> ---
>>  drivers/acpi/acpica/dscontrol.c |    2 +-
>>  drivers/acpi/acpica/dswexec.c   |    3 +--
>>  drivers/acpi/acpica/dswload.c   |    2 +-
>>  drivers/acpi/acpica/dswload2.c  |    4 +---
>>  drivers/acpi/acpica/exfldio.c   |    2 +-
>>  drivers/acpi/acpica/exresop.c   |    4 ++--
>>  drivers/acpi/acpica/exstore.c   |    4 ++--
>>  drivers/acpi/acpica/hwgpe.c     |    3 +--
>>  drivers/acpi/acpica/utdelete.c  |    3 +--
>>  drivers/acpi/acpica/utprint.c   |    2 +-
>>  10 files changed, 12 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/acpi/acpica/dscontrol.c 
>> b/drivers/acpi/acpica/dscontrol.c index 4b5b6e859f62..134d53380663 
>> 100644
>> --- a/drivers/acpi/acpica/dscontrol.c
>> +++ b/drivers/acpi/acpica/dscontrol.c
>> @@ -62,7 +62,7 @@ acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state,
>>                         }
>>                 }
>>
>> -               /*lint -fallthrough */
>> +               fallthrough;
>>
>>         case AML_IF_OP:
>>                 /*
>> diff --git a/drivers/acpi/acpica/dswexec.c 
>> b/drivers/acpi/acpica/dswexec.c index 1d4f8c81028c..41f6cb61778a 
>> 100644
>> --- a/drivers/acpi/acpica/dswexec.c
>> +++ b/drivers/acpi/acpica/dswexec.c
>> @@ -598,8 +598,7 @@ acpi_status acpi_ds_exec_end_op(struct acpi_walk_state *walk_state)
>>                                         break;
>>                                 }
>>
>> -                               /* Fall through */
>> -                               /*lint -fallthrough */
>> +                               fallthrough;
>>
>>                         case AML_INT_EVAL_SUBTREE_OP:
>>
>> diff --git a/drivers/acpi/acpica/dswload.c 
>> b/drivers/acpi/acpica/dswload.c index 27069325b6de..1d8789869dda 
>> 100644
>> --- a/drivers/acpi/acpica/dswload.c
>> +++ b/drivers/acpi/acpica/dswload.c
>> @@ -224,7 +224,7 @@ acpi_ds_load1_begin_op(struct acpi_walk_state *walk_state,
>>                                 break;
>>                         }
>>
>> -                       /*lint -fallthrough */
>> +                       fallthrough;
>>
>>                 default:
>>
>> diff --git a/drivers/acpi/acpica/dswload2.c 
>> b/drivers/acpi/acpica/dswload2.c index edadbe146506..de367e8e4cf4 
>> 100644
>> --- a/drivers/acpi/acpica/dswload2.c
>> +++ b/drivers/acpi/acpica/dswload2.c
>> @@ -213,9 +213,7 @@ acpi_ds_load2_begin_op(struct acpi_walk_state *walk_state,
>>                              parse_flags & ACPI_PARSE_MODULE_LEVEL)) {
>>                                 break;
>>                         }
>> -
>> -                       /*lint -fallthrough */
>> -
>> +                       fallthrough;
>>                 default:
>>
>>                         /* All other types are an error */ diff --git 
>> a/drivers/acpi/acpica/exfldio.c b/drivers/acpi/acpica/exfldio.c index 
>> ade35ff1c7ba..677ba3ab1482 100644
>> --- a/drivers/acpi/acpica/exfldio.c
>> +++ b/drivers/acpi/acpica/exfldio.c
>> @@ -434,7 +434,7 @@ acpi_ex_field_datum_io(union acpi_operand_object *obj_desc,
>>                  * region_field case and write the datum to the Operation Region
>>                  */
>>
>> -               /*lint -fallthrough */
>> +               fallthrough;
>>
>>         case ACPI_TYPE_LOCAL_REGION_FIELD:
>>                 /*
>> diff --git a/drivers/acpi/acpica/exresop.c 
>> b/drivers/acpi/acpica/exresop.c index 4d1b22971d58..7c8676adcf43 
>> 100644
>> --- a/drivers/acpi/acpica/exresop.c
>> +++ b/drivers/acpi/acpica/exresop.c
>> @@ -198,7 +198,7 @@ acpi_ex_resolve_operands(u16 opcode,
>>
>>                                         target_op = AML_DEBUG_OP;
>>
>> -                                       /*lint -fallthrough */
>> +                                       fallthrough;
>>
>>                                 case ACPI_REFCLASS_ARG:
>>                                 case ACPI_REFCLASS_LOCAL:
>> @@ -264,7 +264,7 @@ acpi_ex_resolve_operands(u16 opcode,
>>                          * Else not a string - fall through to the normal Reference
>>                          * case below
>>                          */
>> -                       /*lint -fallthrough */
>> +                       fallthrough;
>>
>>                 case ARGI_REFERENCE:    /* References: */
>>                 case ARGI_INTEGER_REF:
>> diff --git a/drivers/acpi/acpica/exstore.c 
>> b/drivers/acpi/acpica/exstore.c index 3adc0a29d890..fcf8dff56c5b 
>> 100644
>> --- a/drivers/acpi/acpica/exstore.c
>> +++ b/drivers/acpi/acpica/exstore.c
>> @@ -96,7 +96,7 @@ acpi_ex_store(union acpi_operand_object *source_desc,
>>                         return_ACPI_STATUS(AE_OK);
>>                 }
>>
>> -               /*lint -fallthrough */
>> +               fallthrough;
>>
>>         default:
>>
>> @@ -422,7 +422,7 @@ acpi_ex_store_object_to_node(union acpi_operand_object *source_desc,
>>                                 break;
>>                         }
>>
>> -                       /* Fallthrough */
>> +                       fallthrough;
>>
>>                 case ACPI_TYPE_DEVICE:
>>                 case ACPI_TYPE_EVENT:
>> diff --git a/drivers/acpi/acpica/hwgpe.c b/drivers/acpi/acpica/hwgpe.c 
>> index 49c46d4dd070..19d574f64c78 100644
>> --- a/drivers/acpi/acpica/hwgpe.c
>> +++ b/drivers/acpi/acpica/hwgpe.c
>> @@ -95,8 +95,7 @@ acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u32 action)
>>                 if (!(register_bit & gpe_register_info->enable_mask)) {
>>                         return (AE_BAD_PARAMETER);
>>                 }
>> -
>> -               /*lint -fallthrough */
>> +               fallthrough;
>>
>>         case ACPI_GPE_ENABLE:
>>
>> diff --git a/drivers/acpi/acpica/utdelete.c 
>> b/drivers/acpi/acpica/utdelete.c index c365faf4e6cd..6db09eb9d257 
>> 100644
>> --- a/drivers/acpi/acpica/utdelete.c
>> +++ b/drivers/acpi/acpica/utdelete.c
>> @@ -111,8 +111,7 @@ static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
>>                         (void)acpi_ev_delete_gpe_block(object->device.
>>                                                        gpe_block);
>>                 }
>> -
>> -               /*lint -fallthrough */
>> +               fallthrough;
>>
>>         case ACPI_TYPE_PROCESSOR:
>>         case ACPI_TYPE_THERMAL:
>> diff --git a/drivers/acpi/acpica/utprint.c 
>> b/drivers/acpi/acpica/utprint.c index 681c11f4af4e..f7e43baf5ff2 
>> 100644
>> --- a/drivers/acpi/acpica/utprint.c
>> +++ b/drivers/acpi/acpica/utprint.c
>> @@ -475,7 +475,7 @@ int vsnprintf(char *string, acpi_size size, const char *format, va_list args)
>>                 case 'X':
>>
>>                         type |= ACPI_FORMAT_UPPER;
>> -                       /* FALLTHROUGH */
>> +                       fallthrough;
>>
>>                 case 'x':
>>
>>