Re: [PATCH] acpi: Fix ARM32 platforms compile issue introduced by fw_table changes

[Dave Jiang]

On 11/21/23 14:49, Sam Edwards wrote:
> 
> 
> On 11/21/23 07:58, Dave Jiang wrote:
>> Linus reported that:
>> After commit a103f46633fd the kernel stopped compiling for
>> several ARM32 platforms that I am building with a bare metal
>> compiler. Bare metal compilers (arm-none-eabi-) don't
>> define __linux__.
>>
>> This is because the header <acpi/platform/acenv.h> is now
>> in the include path for <linux/irq.h>:
>>
>>    CC      arch/arm/kernel/irq.o
>>    CC      kernel/sysctl.o
>>    CC      crypto/api.o
>> In file included from ../include/acpi/acpi.h:22,
>>                   from ../include/linux/fw_table.h:29,
>>                   from ../include/linux/acpi.h:18,
>>                   from ../include/linux/irqchip.h:14,
>>                   from ../arch/arm/kernel/irq.c:25:
>> ../include/acpi/platform/acenv.h:218:2: error: #error Unknown target environment
>>    218 | #error Unknown target environment
>>        |  ^~~~~
>>
>> The issue is caused by the introducing of splitting out the ACPI code to
>> support the new generic fw_table code.
>>
>> Rafael suggested moving the fw_table.h include in linux/acpi.h to below
>> the asm/acpi.h. The move also helped with eliminating the inclusion of
>> acpi/acpi.h in fw_table.h. The unfortunate circular inclusion of
>> linux/acpi.h is needed for fw_table.h due fw_table code needing the
>> defined acpi structs in order to build.
>>
>> Fixes: a103f46633fd ("acpi: Move common tables helper functions to common lib")
>> Reported-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
>> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
>> ---
>>   include/linux/acpi.h     |   23 ++++++++++++-----------
>>   include/linux/fw_table.h |    1 -
>>   2 files changed, 12 insertions(+), 12 deletions(-)
>>
>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
>> index 54189e0e5f41..2789beb26138 100644
>> --- a/include/linux/acpi.h
>> +++ b/include/linux/acpi.h
>> @@ -15,7 +15,6 @@
>>   #include <linux/mod_devicetable.h>
>>   #include <linux/property.h>
>>   #include <linux/uuid.h>
>> -#include <linux/fw_table.h>
>>     struct irq_domain;
>>   struct irq_domain_ops;
>> @@ -25,16 +24,6 @@ struct irq_domain_ops;
>>   #endif
>>   #include <acpi/acpi.h>
>>   -#ifdef CONFIG_ACPI_TABLE_LIB
>> -#define EXPORT_SYMBOL_ACPI_LIB(x) EXPORT_SYMBOL_NS_GPL(x, ACPI)
>> -#define __init_or_acpilib
>> -#define __initdata_or_acpilib
>> -#else
>> -#define EXPORT_SYMBOL_ACPI_LIB(x)
>> -#define __init_or_acpilib __init
>> -#define __initdata_or_acpilib __initdata
>> -#endif
>> -
>>   #ifdef    CONFIG_ACPI
>>     #include <linux/list.h>
>> @@ -48,6 +37,18 @@ struct irq_domain_ops;
>>   #include <acpi/acpi_io.h>
>>   #include <asm/acpi.h>
>>   +#include <linux/fw_table.h>
>> +
>> +#ifdef CONFIG_ACPI_TABLE_LIB
>> +#define EXPORT_SYMBOL_ACPI_LIB(x) EXPORT_SYMBOL_NS_GPL(x, ACPI)
>> +#define __init_or_acpilib
>> +#define __initdata_or_acpilib
>> +#else
>> +#define EXPORT_SYMBOL_ACPI_LIB(x)
>> +#define __init_or_acpilib __init
>> +#define __initdata_or_acpilib __initdata
>> +#endif
>> +
>>   static inline acpi_handle acpi_device_handle(struct acpi_device *adev)
>>   {
>>       return adev ? adev->handle : NULL;
>> diff --git a/include/linux/fw_table.h b/include/linux/fw_table.h
>> index ff8fa58d5818..a722300c215b 100644
>> --- a/include/linux/fw_table.h
>> +++ b/include/linux/fw_table.h
>> @@ -26,7 +26,6 @@ struct acpi_subtable_proc {
>>   };
>>     #include <linux/acpi.h>
>> -#include <acpi/acpi.h>
> 
> Hi Dave,
> 
> Seems to me that the #include <linux/acpi.h> should go too, to break the circular including cycle. If it remains, I fear that there could be subtle problems in the future depending on which header is included first in a compilation unit. It sounds now like the only correct way to get fw_table.h included is transitively via linux/acpi.h (of note: lib/fw_table.c will have to be updated; it's the only file that currently breaks this rule) so that removal will just help enforce this. Plus, includes in the middle of non-preprocessor declarations are a (sometimes necessary, definitely not here) code smell, in my view.
> 
> If this include must remain for some reason, perhaps a comment should be added to call attention to the circular situation and provide justification?

If I remove linux/acpi.h as well in fw_table.h and place linux/acpi.h in fw_table.c before fw_table.h inclusion, it now seems to solve my build issue. Will that work? I'll send a v2.  
> 
> Cheers,
> Sam
> 
>>     union acpi_subtable_headers {
>>       struct acpi_subtable_header common;
>>
>>
>>
>>