linux-kernel - Re: [PATCH v2 03/44] cpuidle/poll: Ensure IRQ state is invariant

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Message-ID: <20220919131927.GA58444@lothringen>
Date:   Mon, 19 Sep 2022 15:19:27 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
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Subject: Re: [PATCH v2 03/44] cpuidle/poll: Ensure IRQ state is invariant

On Mon, Sep 19, 2022 at 11:59:42AM +0200, Peter Zijlstra wrote:
> cpuidle_state::enter() methods should be IRQ invariant

Got a bit confused with the invariant thing since the first chunck I
see in this patch is a conversion to an non-traceable local_irq_enable().

Maybe just add a short mention about that and why?

Thanks.

> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/cpuidle/poll_state.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> --- a/drivers/cpuidle/poll_state.c
> +++ b/drivers/cpuidle/poll_state.c
> @@ -17,7 +17,7 @@ static int __cpuidle poll_idle(struct cp
>  
>  	dev->poll_time_limit = false;
>  
> -	local_irq_enable();
> +	raw_local_irq_enable();
>  	if (!current_set_polling_and_test()) {
>  		unsigned int loop_count = 0;
>  		u64 limit;
> @@ -36,6 +36,8 @@ static int __cpuidle poll_idle(struct cp
>  			}
>  		}
>  	}
> +	raw_local_irq_disable();
> +
>  	current_clr_polling();
>  
>  	return index;
> 
>