linux-kernel - Re: [PATCH -next] powerpc: kernel/time.c

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Message-ID: <5f4ec5e0-af9c-ba47-4a01-589b1b724cb9@csgroup.eu>
Date:   Tue, 23 Mar 2021 07:33:41 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     "heying (H)" <heying24@...wei.com>, mpe@...erman.id.au,
        benh@...nel.crashing.org, paulus@...ba.org, npiggin@...il.com,
        msuchanek@...e.de, peterz@...radead.org, geert+renesas@...der.be,
        kernelfans@...il.com, frederic@...nel.org
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] powerpc: kernel/time.c - cleanup warnings



Le 23/03/2021 à 07:21, heying (H) a écrit :
> Dear Christophe,
> 
> 
> 在 2021/3/18 10:28, heying (H) 写道:
>>
>> 在 2021/3/17 19:16, Christophe Leroy 写道:
>>>
>>>
>>> Le 17/03/2021 à 11:34, He Ying a écrit :
>>>> We found these warnings in arch/powerpc/kernel/time.c as follows:
>>>> warning: symbol 'decrementer_max' was not declared. Should it be static?
>>>> warning: symbol 'rtc_lock' was not declared. Should it be static?
>>>> warning: symbol 'dtl_consumer' was not declared. Should it be static?
>>>>
>>>> Declare 'decrementer_max' in arch/powerpc/include/asm/time.h. And include
>>>> proper header in which 'rtc_lock' is declared. Move 'dtl_consumer'
>>>> definition behind "include <asm/dtl.h>" because 'dtl_consumer' is declared
>>>> there.
>>>>
>>>> Reported-by: Hulk Robot <hulkci@...wei.com>
>>>> Signed-off-by: He Ying <heying24@...wei.com>
>>>> ---
>>>>   arch/powerpc/include/asm/time.h | 1 +
>>>>   arch/powerpc/kernel/time.c      | 7 +++----
>>>>   2 files changed, 4 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
>>>> index 8dd3cdb25338..2cd2b50bedda 100644
>>>> --- a/arch/powerpc/include/asm/time.h
>>>> +++ b/arch/powerpc/include/asm/time.h
>>>> @@ -22,6 +22,7 @@ extern unsigned long tb_ticks_per_jiffy;
>>>>   extern unsigned long tb_ticks_per_usec;
>>>>   extern unsigned long tb_ticks_per_sec;
>>>>   extern struct clock_event_device decrementer_clockevent;
>>>> +extern u64 decrementer_max;
>>>>       extern void generic_calibrate_decr(void);
>>>> diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
>>>> index b67d93a609a2..409967713ca6 100644
>>>> --- a/arch/powerpc/kernel/time.c
>>>> +++ b/arch/powerpc/kernel/time.c
>>>> @@ -55,6 +55,7 @@
>>>>   #include <linux/sched/cputime.h>
>>>>   #include <linux/sched/clock.h>
>>>>   #include <linux/processor.h>
>>>> +#include <linux/mc146818rtc.h>
>>>
>>> I don't think that's the good place. It has no link to powerpc, it is only by chance that it has 
>>> the same name.
>>>
>>> As rtc_lock is defined in powerpc time.c, I think you should declare it in powerpc asm/time.h
>>
>> My first thought was the same as yours. I tried to add declaration in powerpc asm/time.h, but got 
>> a compiling error:
>>
>> drivers/rtc/rtc-vr41xx.c:75:24: error: static declaration of ‘rtc_lock’ follows non-static 
>> declaration
>>  static DEFINE_SPINLOCK(rtc_lock);
>>
>> In file included from ./arch/powerpc/include/asm/delay.h:7:0,
>>                  from ./arch/powerpc/include/asm/io.h:33,
>>                  from ./include/linux/io.h:13,
>>                  from drivers/rtc/rtc-vr41xx.c:11:
>> ./arch/powerpc/include/asm/time.h:25:19: note: previous declaration of ‘rtc_lock’ was here
>>  extern spinlock_t rtc_lock;
>>
>> There's a conflict. Perhaps I can rename it in drivers/rtc/rtc-vr41xx.c.
>>
>>
>> But I find an existing declaration in linux/mc146818rtc.h and there's only one definition for 
>> 'rtc_lock' in powerpc.
>>
>> There's some includes of mc146818rtc.h in powperc. I wonder they point to the same thing. But I'm 
>> not very sure
>>
>> because the header's name looks a bit strange.
> 
> How about including mc146818rtc.h in powperpc kernel/time.c? May I have your opinions please?
> 

As I said, mc146818rtc.h is not related to powerpc, and if it works that's just chance, and there is 
no certainty that it will still work in the future.

If you can't find a clean solution, it is better to leave the warning.

Christophe