linux-kernel - Re: [PATCH V3 -next] powerpc: kernel/time.c

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Message-ID: <18a8d444-f1a5-61e0-b9f2-f85c03d71686@huawei.com>
Date:   Wed, 24 Mar 2021 17:46:19 +0800
From:   "heying (H)" <heying24@...wei.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     <mpe@...erman.id.au>, <benh@...nel.crashing.org>,
        <paulus@...ba.org>, <a.zummo@...ertech.it>,
        <christophe.leroy@...roup.eu>, <npiggin@...il.com>,
        <msuchanek@...e.de>, <tglx@...utronix.de>, <peterz@...radead.org>,
        <geert@...ux-m68k.org>, <geert+renesas@...der.be>,
        <kernelfans@...il.com>, <frederic@...nel.org>,
        <linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
        <linux-rtc@...r.kernel.org>
Subject: Re: [PATCH V3 -next] powerpc: kernel/time.c - cleanup warnings

Dear Alexandre,


在 2021/3/24 17:29, Alexandre Belloni 写道:
> On 24/03/2021 05:09:39-0400, He Ying wrote:
>> 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 powerpc asm/time.h.
>> Include linux/mc146818rtc.h in powerpc kernel/time.c where 'rtc_lock'
>> is declared. And remove duplicated declaration of 'rtc_lock' in powerpc
>> platforms/chrp/time.c because it has included linux/mc146818rtc.h.
>> Move 'dtl_consumer' definition behind "include <asm/dtl.h>" because it
>> is declared there.
>>
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Signed-off-by: He Ying <heying24@...wei.com>
>> ---
>> V2:
>> - Instead of including linux/mc146818rtc.h in powerpc kernel/time.c, declare
>>    rtc_lock in powerpc asm/time.h.
>> V3:
>> - Recover to V1, that is including linux/mc146818rtc.h in powerpc
>>    kernel/time.c. And remove duplicated declaration of 'rtc_lock' in powerpc
>>    platforms/chrp/time.c because it has included linux/mc146818rtc.h.
>>
>>   arch/powerpc/include/asm/time.h    | 1 +
>>   arch/powerpc/kernel/time.c         | 9 ++++-----
>>   arch/powerpc/platforms/chrp/time.c | 2 --
>>   3 files changed, 5 insertions(+), 7 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..ac81f043bf49 100644
>> --- a/arch/powerpc/kernel/time.c
>> +++ b/arch/powerpc/kernel/time.c
>> @@ -55,8 +55,9 @@
>>   #include <linux/sched/cputime.h>
>>   #include <linux/sched/clock.h>
>>   #include <linux/processor.h>
>> -#include <asm/trace.h>
>> +#include <linux/mc146818rtc.h>
> I'm fine with that but I really think my suggestion to make the rtc_lock
> local to the platforms was better because it is only used to synchronize
> between concurrent invocations of chrp_set_rtc_time or
> maple_set_rtc_time. The rtc core will never do that and the only case
> would be concurrent calls to rtc_ops.set_time and
> update_persistent_clock64 (which should also be removed at some point).

Many thanks for your suggestion. As you suggest, rtc_lock should be 
local to platforms.

Does it mean not only powerpc but also all other platforms should adapt 
this change?

It might be a big change. I have no idea if that's OK. What are other 
maintainers' opinions?


Thanks.