Re: checkpatch: Question regarding asmlinkage and storage class
From: Joe Perches
Date: Sun Mar 19 2017 - 04:37:16 EST
On Sat, 2017-03-18 at 13:15 +0100, Paul Menzel wrote:
> Dear checkpatch developers,
>
>
> The coreboot project started using checkpatch.pl, and now some effort
> is going into fixing issues pointed out by `checkpatch.pl`.
>
> The file `src/arch/x86/acpi_s3.c` in coreboot contains the code below.
>
> ```
> ÂÂÂ205 void (*acpi_do_wakeup)(uintptr_t vector, u32 backup_source, u32 backup_target,
> ÂÂÂ206 u32 backup_size) asmlinkage = (void *)WAKEUP_BASE;
> ```
>
> The warning is
>
> > WARNING: storage class should be at the beginning of the declaration
>
> which raised the question below [2].
>
> > And I am waiting for someone to answer why checkpatch.pl claims
> > asmlinkage as a storage-class in the first place.
[]
> In coreboot the macro is defined similarly to Linux.
>
> ```
> #define asmlinkage __attribute__((regparm(0)))
> #define alwaysinline inline __attribute__((always_inline))
> ```
Are they similar?
$ git grep -i "define.*ASMLINKAGE\b" include
include/linux/linkage.h:#define CPP_ASMLINKAGE extern "C"
include/linux/linkage.h:#define CPP_ASMLINKAGE
include/linux/linkage.h:#define asmlinkage CPP_ASMLINKAGE
I believe asmlinkage is defined just to avoid
possible asm/c++ symbol decorations.
> In Linux, commit 9c0ca6f9Â(update checkpatch.pl to version 0.10) seems
> to have introduced the check. The commit message contains âasmlinkage
> is also a storage typeâ.
>
> Furthermore, `checkpatch.pl` doesnât seem to warn about the code below.
>
> ```
> void __attribute__((weak)) mainboard_suspend_resume(void)
> ```
>
> This raises the question below.
>
> > It appears coreboot proper mostly followed this placement for
> > function attributes before. It would be nice if we were consistent,
> > specially if checkpatch starts to complaint about these.
>
> Is there another reason, besides not having that implemented?
>
> I am looking forward to your answers.
>
>
> Kind regards,
>
> Paul
>
>
> [1] https://review.coreboot.org/#/c/18865/1/src/arch/x86/acpi_s3.c@205
> [2] https://review.coreboot.org/18865/
> [3] https://review.coreboot.org/#/c/18865/1/src/arch/x86/acpi_s3.c@244