Re: [PATCH v3 1/5] rfi-flush: Move the logic to avoid a redo into the debugfs code

[Murilo Opsfelder Araujo <muriloo@linux.vnet.ibm.com>]

On 03/14/2018 07:40 PM, Mauricio Faria de Oliveira wrote:
> From: Michael Ellerman <mpe@ellerman.id.au>
> 
> rfi_flush_enable() includes a check to see if we're already
> enabled (or disabled), and in that case does nothing.
> 
> But that means calling setup_rfi_flush() a 2nd time doesn't actually
> work, which is a bit confusing.
> 
> Move that check into the debugfs code, where it really belongs.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
> ---
>  arch/powerpc/kernel/setup_64.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index c388cc3..3efc01a 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -846,9 +846,6 @@ static void do_nothing(void *unused)
> 
>  void rfi_flush_enable(bool enable)
>  {
> -	if (rfi_flush == enable)
> -		return;
> -
>  	if (enable) {
>  		do_rfi_flush_fixups(enabled_flush_types);
>  		on_each_cpu(do_nothing, NULL, 1);
> @@ -902,13 +899,19 @@ void __init setup_rfi_flush(enum l1d_flush_type types, bool enable)
>  #ifdef CONFIG_DEBUG_FS
>  static int rfi_flush_set(void *data, u64 val)
>  {
> +	bool enable;
> +
>  	if (val == 1)
> -		rfi_flush_enable(true);
> +		enable = true;
>  	else if (val == 0)
> -		rfi_flush_enable(false);
> +		enable = false;
>  	else
>  		return -EINVAL;
> 
> +	/* Only do anything if we're changing state */
> +	if (enable != rfi_flush)

Hi, Mauricio.

Do we need to take into account if no_rfi_flush == true?

    if ((enable != rfi_flush) && !no_rfi_flush)

> +		rfi_flush_enable(enable);
> +
>  	return 0;
>  }
> 

Cheers
Murilo