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

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Date:   Sun, 3 Dec 2017 21:22:42 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:     LKML <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 Sun, Dec 3, 2017 at 2:33 PM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
> 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.


Hello, Paul,

It assumes my previous patch applied.
"smp/hotplug: move step CPUHP_AP_SMPCFD_DYING to the correct place"

https://www.spinics.net/lists/linux-tip-commits/msg41542.html

Thanks,
Lai

>
>                                                         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)
>>
>