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

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Message-ID: <5ee06736-7fc4-7993-a8b5-042e1890a6de@huawei.com>
Date:   Thu, 18 Mar 2021 10:28:09 +0800
From:   "heying (H)" <heying24@...wei.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        <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


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.

>
>
>>   #include <asm/trace.h>
>>     #include <asm/interrupt.h>
>> @@ -150,10 +151,6 @@ bool tb_invalid;
>>   u64 __cputime_usec_factor;
>>   EXPORT_SYMBOL(__cputime_usec_factor);
>>   -#ifdef CONFIG_PPC_SPLPAR
>> -void (*dtl_consumer)(struct dtl_entry *, u64);
>> -#endif
>> -
>>   static void calc_cputime_factors(void)
>>   {
>>       struct div_result res;
>> @@ -179,6 +176,8 @@ static inline unsigned long read_spurr(unsigned 
>> long tb)
>>     #include <asm/dtl.h>
>>   +void (*dtl_consumer)(struct dtl_entry *, u64);
>> +
>>   /*
>>    * Scan the dispatch trace log and count up the stolen time.
>>    * Should be called with interrupts disabled.
>>
> .