linux-kernel - Re: [PATCH 4/4] context_tracking: uninitialize static variables

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Message-ID: <20200803093751.GD2674@hirez.programming.kicks-ass.net>
Date:   Mon, 3 Aug 2020 11:37:51 +0200
From:   peterz@...radead.org
To:     Jules Irenge <jbi.octave@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Frederic Weisbecker <frederic@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH 4/4] context_tracking: uninitialize static variables

On Sat, Aug 01, 2020 at 07:46:03PM +0100, Jules Irenge wrote:
> Checkpatch tool reports an error at a staic variable declaration
> 
> "ERROR: do not initialise statics to false"
> 
> This is due to the fact that this variable is stored in the buffer
> In the .bss section, one can not set an initial value
> Here we can trust the compiler to automatically set them to false.
> The variable has since been uninitialized.
> 
> Signed-off-by: Jules Irenge <jbi.octave@...il.com>
> ---
>  kernel/context_tracking.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
> index 36a98c48aedc..21881c534152 100644
> --- a/kernel/context_tracking.c
> +++ b/kernel/context_tracking.c
> @@ -190,7 +190,7 @@ NOKPROBE_SYMBOL(context_tracking_user_exit);
>  
>  void __init context_tracking_cpu_set(int cpu)
>  {
> -	static __initdata bool initialized = false;
> +	static __initdata bool initialized;

So personally I prefer having the '= false' there. It used to be that
compilers were stupid and would put any initialized static variable in
.data, even if it was initialized with 0. But AFAIK compilers are no
longer that stupid.