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

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Message-ID: <YFsGYgdNH5HrlqDJ@piout.net>
Date:   Wed, 24 Mar 2021 10:29:06 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     He Ying <heying24@...wei.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

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).

>  
> +#include <asm/trace.h>
>  #include <asm/interrupt.h>
>  #include <asm/io.h>
>  #include <asm/nvram.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.
> diff --git a/arch/powerpc/platforms/chrp/time.c b/arch/powerpc/platforms/chrp/time.c
> index acde7bbe0716..b94dfd5090d8 100644
> --- a/arch/powerpc/platforms/chrp/time.c
> +++ b/arch/powerpc/platforms/chrp/time.c
> @@ -30,8 +30,6 @@
>  
>  #include <platforms/chrp/chrp.h>
>  
> -extern spinlock_t rtc_lock;
> -
>  #define NVRAM_AS0  0x74
>  #define NVRAM_AS1  0x75
>  #define NVRAM_DATA 0x77
> -- 
> 2.17.1
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com