linux-kernel - Re: [PATCH] cpu/hotplug: merge cpuhp_bp_states&cpuhp_ap_states as cpuhp_hp

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Date:   Sat, 2 Dec 2017 22:33:55 -0800
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     Lai Jiangshan <jiangshanlai@...il.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH] cpu/hotplug: merge cpuhp_bp_states&cpuhp_ap_states as
 cpuhp_hp_states

On Fri, Dec 01, 2017 at 09:50:05PM +0800, Lai Jiangshan wrote:
> cpuhp_bp_states&cpuhp_ap_states have diffent set of steps
> without any conflicting configed steps, so that they can
> be merged.
> 
> The original `[CPUHP_BRINGUP_CPU] = { },` is removed, because
> the new cpuhp_hp_states has CPUHP_ONLINE index which is larger
> than CPUHP_BRINGUP_CPU.
> 
> Signed-off-by: Lai Jiangshan <jiangshanlai@...il.com>

Hello, Lai,

What is this against?  I tried testing it, but it doesn't apply to
v4.15-rc1 or v4.14.

							Thanx, Paul

> ---
>  kernel/cpu.c | 42 +++++++++++++++---------------------------
>  1 file changed, 15 insertions(+), 27 deletions(-)
> 
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 7891aecc6aec..c27963066333 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -124,8 +124,7 @@ struct cpuhp_step {
>  };
> 
>  static DEFINE_MUTEX(cpuhp_state_mutex);
> -static struct cpuhp_step cpuhp_bp_states[];
> -static struct cpuhp_step cpuhp_ap_states[];
> +static struct cpuhp_step cpuhp_hp_states[];
> 
>  static bool cpuhp_is_ap_state(enum cpuhp_state state)
>  {
> @@ -138,10 +137,7 @@ static bool cpuhp_is_ap_state(enum cpuhp_state state)
> 
>  static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
>  {
> -	struct cpuhp_step *sp;
> -
> -	sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
> -	return sp + state;
> +	return cpuhp_hp_states + state;
>  }
> 
>  /**
> @@ -1224,7 +1220,7 @@ int __boot_cpu_id;
>  #endif /* CONFIG_SMP */
> 
>  /* Boot processor state steps */
> -static struct cpuhp_step cpuhp_bp_states[] = {
> +static struct cpuhp_step cpuhp_hp_states[] = {
>  	[CPUHP_OFFLINE] = {
>  		.name			= "offline",
>  		.startup.single		= NULL,
> @@ -1289,24 +1285,6 @@ static struct cpuhp_step cpuhp_bp_states[] = {
>  		.teardown.single	= NULL,
>  		.cant_stop		= true,
>  	},
> -	/*
> -	 * Handled on controll processor until the plugged processor manages
> -	 * this itself.
> -	 */
> -	[CPUHP_TEARDOWN_CPU] = {
> -		.name			= "cpu:teardown",
> -		.startup.single		= NULL,
> -		.teardown.single	= takedown_cpu,
> -		.cant_stop		= true,
> -	},
> -#else
> -	[CPUHP_BRINGUP_CPU] = { },
> -#endif
> -};
> -
> -/* Application processor state steps */
> -static struct cpuhp_step cpuhp_ap_states[] = {
> -#ifdef CONFIG_SMP
>  	/* Final state before CPU kills itself */
>  	[CPUHP_AP_IDLE_DEAD] = {
>  		.name			= "idle:dead",
> @@ -1340,6 +1318,16 @@ static struct cpuhp_step cpuhp_ap_states[] = {
>  	[CPUHP_AP_ONLINE] = {
>  		.name			= "ap:online",
>  	},
> +	/*
> +	 * Handled on controll processor until the plugged processor manages
> +	 * this itself.
> +	 */
> +	[CPUHP_TEARDOWN_CPU] = {
> +		.name			= "cpu:teardown",
> +		.startup.single		= NULL,
> +		.teardown.single	= takedown_cpu,
> +		.cant_stop		= true,
> +	},
>  	/* Handle smpboot threads park/unpark */
>  	[CPUHP_AP_SMPBOOT_THREADS] = {
>  		.name			= "smpboot/threads:online",
> @@ -1408,11 +1396,11 @@ static int cpuhp_reserve_state(enum cpuhp_state state)
> 
>  	switch (state) {
>  	case CPUHP_AP_ONLINE_DYN:
> -		step = cpuhp_ap_states + CPUHP_AP_ONLINE_DYN;
> +		step = cpuhp_hp_states + CPUHP_AP_ONLINE_DYN;
>  		end = CPUHP_AP_ONLINE_DYN_END;
>  		break;
>  	case CPUHP_BP_PREPARE_DYN:
> -		step = cpuhp_bp_states + CPUHP_BP_PREPARE_DYN;
> +		step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN;
>  		end = CPUHP_BP_PREPARE_DYN_END;
>  		break;
>  	default:
> -- 
> 2.13.6 (Apple Git-96)
>