Re: [PATCH] powerpc: Fix missing prototype problems for "arch/powerpc/kernel/setup_64.c"

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 15/03/2021 à 13:57, Cédric Le Goater a écrit :
> On 3/15/21 1:48 PM, heying (H) wrote:
>>
>> 在 2021/3/15 20:17, Christophe Leroy 写道:
>>> You subject doesn't match the content of the patch.
>> OK. I'll adapt that.
>>>
>>> Le 15/03/2021 à 13:04, He Ying a écrit :
>>>> The variables 'uaccess_fulsh' and 'entry_flush' are not referenced
>>>> outside the file. So define them as static to avoid the warnings.
>>>>
>>>> And add a prototype for the function 'panic_smp_self_stop' for the
>>>> same purpose.
>>>>
>>>> Sparse also warns that 'rfi_flush' should be static. However, it's
>>>> referenced outside the file.
>>>
>>> To clear that warning, you have to include asm/security_features.h, rfi_flush is declared there.
>> Do you mean that I should include this header in arch/powerpc/kernel/setup_64.c?
> 
> yes.
> 
>>>
>>>>
>>>> The warnings about the file reported by sparse are as follows:
>>>> arch/powerpc/kernel/setup_64.c:422:6: warning: symbol 'panic_smp_self_stop' was not declared. Should it be static?
>>>> arch/powerpc/kernel/setup_64.c:951:6: warning: symbol 'rfi_flush' was not declared. Should it be static?
>>>> arch/powerpc/kernel/setup_64.c:952:6: warning: symbol 'entry_flush' was not declared. Should it be static?
>>>> arch/powerpc/kernel/setup_64.c:953:6: warning: symbol 'uaccess_flush' was not declared. Should it be static?
>>>>
>>>> Reported-by: Hulk Robot <hulkci@huawei.com>
>>>> Signed-off-by: He Ying <heying24@huawei.com>
>>>> ---
>>>>    arch/powerpc/kernel/setup_64.c | 6 ++++--
>>>>    1 file changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
>>>> index 560ed8b975e7..603aacd8527b 100644
>>>> --- a/arch/powerpc/kernel/setup_64.c
>>>> +++ b/arch/powerpc/kernel/setup_64.c
>>>> @@ -71,6 +71,8 @@
>>>>      #include "setup.h"
>>>>    +extern void panic_smp_self_stop(void);
>>>> +
>>>
>>> For function prototypes 'extern' is unneeded and deprecated.
>>>
>>> And function prototypes should go in an header file.
>>>
>>> panic_smp_self_stop() is called from kernel/panic.c , it should be declared in one of the generic linux header files I think.
>> Yes, you're right. But I have no idea which header it should be declared in. May I have your suggestions?
> 
> arch/powerpc/include/asm/bug.h looks like a good place.

Why declaring it in a powerpc header ?

It's a weak function defined in core part of kernel (kernel/panic.c).

I think it should go in a common header, just like for instance arch_thaw_secondary_cpus_begin()

> 
> C.
> 
>>>
>>>>    int spinning_secondaries;
>>>>    u64 ppc64_pft_size;
>>>>    @@ -949,8 +951,8 @@ static bool no_rfi_flush;
>>>>    static bool no_entry_flush;
>>>>    static bool no_uaccess_flush;
>>>>    bool rfi_flush;
>>>> -bool entry_flush;
>>>> -bool uaccess_flush;
>>>> +static bool entry_flush;
>>>> +static bool uaccess_flush;
>>>>    DEFINE_STATIC_KEY_FALSE(uaccess_flush_key);
>>>>    EXPORT_SYMBOL(uaccess_flush_key);
>>>>
>>> .