linux-kernel - Re: [PATCH] arm64: perf: no need to initialise statics to 0

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Message-ID: <YnjUqm3lu75+LjqH@FVFF77S0Q05N>
Date:   Mon, 9 May 2022 09:45:30 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Jason Wang <wangborong@...rlc.com>
Cc:     will@...nel.org, catalin.marinas@....com, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: perf: no need to initialise statics to 0

On Sun, May 08, 2022 at 10:23:12AM +0800, Jason Wang wrote:
> Static variables do not need to be initialised to 0, because compiler
> will initialise all uninitialised statics to 0. Thus, remove the
> unneeded initializations.
> 
> Signed-off-by: Jason Wang <wangborong@...rlc.com>

I would strongly prefer that we leave this as-is.

There is no problem with explicitly initializing a static variable to 0, and it
clearly aligns with the cmpxchg arguments below. Removing the initialization
makes that *less* clear.

Thanks,
Mark.

> ---
>  arch/arm64/kernel/perf_event.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
> index cb69ff1e6138..919fdcf8fce6 100644
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -1226,7 +1226,7 @@ static struct ctl_table armv8_pmu_sysctl_table[] = {
>  
>  static void armv8_pmu_register_sysctl_table(void)
>  {
> -	static u32 tbl_registered = 0;
> +	static u32 tbl_registered;
>  
>  	if (!cmpxchg_relaxed(&tbl_registered, 0, 1))
>  		register_sysctl("kernel", armv8_pmu_sysctl_table);
> -- 
> 2.35.1
> 
>