linux-kernel - Re: [PATCH V2] arm64: Neaten show_regs, remove KERN

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Date:   Tue, 25 Oct 2016 18:07:45 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-kernel@...r.kernel.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V2] arm64: Neaten show_regs, remove KERN_CONT

On Tue, Oct 25, 2016 at 09:40:26AM -0700, Joe Perches wrote:
> commit db4b0710fae9 ("arm64: fix show_regs fallout from KERN_CONT changes")
> corrected the KERN_CONT fallout from commit 4bcc595ccd80
> ("printk: reinstate KERN_CONT for printing continuation lines"), but
> the code still has unnecessary KERN_CONT uses.
> 
> Remove the KERN_CONT uses to avoid possible message interleaving.
> 
> Miscellanea:
> 
> o Remove unnecessary trailing blank from the output too.
> o Convert i and top_reg to unsigned int
> o Move the extra blank line after __show_reg to the caller for symmetry
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
>  arch/arm64/kernel/process.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 01753cd7d3f0..5ba12f019bf7 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -168,7 +168,7 @@ void machine_restart(char *cmd)
>  
>  void __show_regs(struct pt_regs *regs)
>  {
> -	int i, top_reg;
> +	unsigned int i, top_reg;

This change is not necessary. These will work perfectly fine as ints;
please leave them as-is.

>  	u64 lr, sp;
>  
>  	if (compat_user_mode(regs)) {
> @@ -190,24 +190,23 @@ void __show_regs(struct pt_regs *regs)
>  
>  	i = top_reg;
>  
> -	while (i >= 0) {
> -		printk("x%-2d: %016llx ", i, regs->regs[i]);
> +	if (i % 2) {

This should be:

	if (i % 2 == 0) {

Otherwise we'll lose x0 in the native case (and x29 will be given a line
of its own).

> +		printk("x%-2d: %016llx\n", i, regs->regs[i]);
>  		i--;
> -
> -		if (i % 2 == 0) {
> -			pr_cont("x%-2d: %016llx ", i, regs->regs[i]);
> -			i--;
> -		}
> -
> -		pr_cont("\n");
>  	}
> -	printk("\n");
> +	while (i > 0) {
> +		printk("x%-2d: %016llx x%-2d: %016llx\n",
> +		       i, regs->regs[i],
> +		       i - 1, regs->regs[i - 1]);
> +		i -= 2;
> +	}
>  }
>  
>  void show_regs(struct pt_regs * regs)
>  {
>  	printk("\n");
>  	__show_regs(regs);
> +	printk("\n");
>  }

Other functions call __show_regs() directly and the trailing newline
there is expected. Please leave it in __show_regs().

Otherwise, this looks fine to me.

Thanks,
Mark.