linux-kernel - Re: [PATCH] acpi: respect const qualifier

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Date:	Fri, 25 Apr 2014 18:02:22 +0300
From:	Sam Protsenko <semen.protsenko@...aro.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] acpi: respect const qualifier

> This is not a mainline kernel problem, surely?

Correct, this warning is just example of possible issue that can be
occurred because of missing "const" qualifier. Actually I saw this
warning in Linaro ACPI kernel (intended for ARMv8 AArch64
architecture).

But I believe that this issue should be fixed in mainline kernel,
because it can cause the same warning in the future.

On 21 April 2014 23:44, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> On Thursday, April 17, 2014 06:53:26 PM Semen Protsenko wrote:
>> This patch fixes next warning:
>>
>> <------------------------------- cut here --------------------------------->
>> drivers/acpi/property.c: In function ‘acpi_free_properties’:
>> drivers/acpi/property.c:35:2: warning: passing argument 1 of ‘acpi_os_free’
>>                               discards ‘const’ qualifier from pointer
>>                               target type [enabled by default]
>>
>>   ACPI_FREE(adev->properties);
>> <------------------------------- cut here --------------------------------->
>
> This is not a mainline kernel problem, surely?
>
>>
>> The problem is next:
>>
>>  - acpi_free_properties() calls ACPI_FREE(), passing "const *"
>>    parameter to it
>>  - ACPI_FREE() is macro for acpi_os_free()
>>  - acpi_os_free() takes "void *" parameter
>>  - acpi_os_free() calls kfree()
>>  - but kfree() requires "const void *" parameter
>>
>> So acpi_os_free() should require "const void *" parameter as well.
>>
>> Signed-off-by: Semen Protsenko <semen.protsenko@...aro.org>
>> ---
>>  include/acpi/platform/aclinux.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
>> index 93c55ed..c6fa763 100644
>> --- a/include/acpi/platform/aclinux.h
>> +++ b/include/acpi/platform/aclinux.h
>> @@ -174,7 +174,7 @@ static inline void *acpi_os_allocate_zeroed(acpi_size size)
>>  #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_allocate_zeroed
>>  #define USE_NATIVE_ALLOCATE_ZEROED
>>
>> -static inline void acpi_os_free(void *memory)
>> +static inline void acpi_os_free(const void *memory)
>>  {
>>       kfree(memory);
>>  }
>>
>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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