[PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[Joao Martins]

When cpus != maxcpus cpuidle-haltpoll will fail to register all vcpus
past the online ones and thus fail to register the idle driver.
This is because cpuidle_add_sysfs() will return with -ENODEV as a
consequence from get_cpu_device() return no device for a non-existing
CPU.

Instead switch to cpuidle_register_driver() and manually register each
of the present cpus through cpuhp_setup_state() and future ones that
get onlined. This mimics similar logic as intel_idle.

Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver")
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 arch/x86/include/asm/cpuidle_haltpoll.h |  4 +-
 arch/x86/kernel/kvm.c                   | 18 +++----
 drivers/cpuidle/cpuidle-haltpoll.c      | 65 +++++++++++++++++++++++--
 include/linux/cpuidle_haltpoll.h        |  4 +-
 4 files changed, 70 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/cpuidle_haltpoll.h b/arch/x86/include/asm/cpuidle_haltpoll.h
index ff8607d81526..c8b39c6716ff 100644
--- a/arch/x86/include/asm/cpuidle_haltpoll.h
+++ b/arch/x86/include/asm/cpuidle_haltpoll.h
@@ -2,7 +2,7 @@
 #ifndef _ARCH_HALTPOLL_H
 #define _ARCH_HALTPOLL_H
 
-void arch_haltpoll_enable(void);
-void arch_haltpoll_disable(void);
+void arch_haltpoll_enable(unsigned int cpu);
+void arch_haltpoll_disable(unsigned int cpu);
 
 #endif
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 8d150e3732d9..a9b6c4e2446d 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -880,32 +880,26 @@ static void kvm_enable_host_haltpoll(void *i)
 	wrmsrl(MSR_KVM_POLL_CONTROL, 1);
 }
 
-void arch_haltpoll_enable(void)
+void arch_haltpoll_enable(unsigned int cpu)
 {
 	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
-		printk(KERN_ERR "kvm: host does not support poll control\n");
-		printk(KERN_ERR "kvm: host upgrade recommended\n");
+		pr_err_once("kvm: host does not support poll control\n");
+		pr_err_once("kvm: host upgrade recommended\n");
 		return;
 	}
 
-	preempt_disable();
 	/* Enable guest halt poll disables host halt poll */
-	kvm_disable_host_haltpoll(NULL);
-	smp_call_function(kvm_disable_host_haltpoll, NULL, 1);
-	preempt_enable();
+	smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
 }
 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
 
-void arch_haltpoll_disable(void)
+void arch_haltpoll_disable(unsigned int cpu)
 {
 	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
 		return;
 
-	preempt_disable();
 	/* Enable guest halt poll disables host halt poll */
-	kvm_enable_host_haltpoll(NULL);
-	smp_call_function(kvm_enable_host_haltpoll, NULL, 1);
-	preempt_enable();
+	smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
 }
 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
 #endif
diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
index 9ac093dcbb01..0d1853a7185e 100644
--- a/drivers/cpuidle/cpuidle-haltpoll.c
+++ b/drivers/cpuidle/cpuidle-haltpoll.c
@@ -11,12 +11,15 @@
  */
 
 #include <linux/init.h>
+#include <linux/cpu.h>
 #include <linux/cpuidle.h>
 #include <linux/module.h>
 #include <linux/sched/idle.h>
 #include <linux/kvm_para.h>
 #include <linux/cpuidle_haltpoll.h>
 
+static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;
+
 static int default_enter_idle(struct cpuidle_device *dev,
 			      struct cpuidle_driver *drv, int index)
 {
@@ -46,6 +49,48 @@ static struct cpuidle_driver haltpoll_driver = {
 	.state_count = 2,
 };
 
+static int haltpoll_cpu_online(unsigned int cpu)
+{
+	struct cpuidle_device *dev;
+
+	dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
+	if (!dev->registered) {
+		dev->cpu = cpu;
+		if (cpuidle_register_device(dev)) {
+			pr_notice("cpuidle_register_device %d failed!\n", cpu);
+			return -EIO;
+		}
+		arch_haltpoll_enable(cpu);
+	}
+
+	return 0;
+}
+
+static void haltpoll_uninit(void)
+{
+	unsigned int cpu;
+
+	cpus_read_lock();
+
+	for_each_online_cpu(cpu) {
+		struct cpuidle_device *dev =
+			per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
+
+		if (!dev->registered)
+			continue;
+
+		arch_haltpoll_disable(cpu);
+		cpuidle_unregister_device(dev);
+	}
+
+	cpuidle_unregister(&haltpoll_driver);
+
+	free_percpu(haltpoll_cpuidle_devices);
+	haltpoll_cpuidle_devices = NULL;
+
+	cpus_read_unlock();
+}
+
 static int __init haltpoll_init(void)
 {
 	int ret;
@@ -56,17 +101,27 @@ static int __init haltpoll_init(void)
 	if (!kvm_para_available())
 		return 0;
 
-	ret = cpuidle_register(&haltpoll_driver, NULL);
-	if (ret == 0)
-		arch_haltpoll_enable();
+	ret = cpuidle_register_driver(drv);
+	if (ret < 0)
+		return ret;
+
+	haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+	if (haltpoll_cpuidle_devices == NULL) {
+		cpuidle_unregister_driver(drv);
+		return -ENOMEM;
+	}
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "idle/haltpoll:online",
+				haltpoll_cpu_online, NULL);
+	if (ret < 0)
+		haltpoll_uninit();
 
 	return ret;
 }
 
 static void __exit haltpoll_exit(void)
 {
-	arch_haltpoll_disable();
-	cpuidle_unregister(&haltpoll_driver);
+	haltpoll_uninit();
 }
 
 module_init(haltpoll_init);
diff --git a/include/linux/cpuidle_haltpoll.h b/include/linux/cpuidle_haltpoll.h
index fe5954c2409e..d50c1e0411a2 100644
--- a/include/linux/cpuidle_haltpoll.h
+++ b/include/linux/cpuidle_haltpoll.h
@@ -5,11 +5,11 @@
 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
 #include <asm/cpuidle_haltpoll.h>
 #else
-static inline void arch_haltpoll_enable(void)
+static inline void arch_haltpoll_enable(unsigned int cpu)
 {
 }
 
-static inline void arch_haltpoll_disable(void)
+static inline void arch_haltpoll_disable(unsigned int cpu)
 {
 }
 #endif
-- 
2.17.1

Re: [PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[Rafael J. Wysocki]

On Wed, Aug 28, 2019 at 8:58 PM Joao Martins <joao.m.martins@oracle.com> wrote:
>
> When cpus != maxcpus cpuidle-haltpoll will fail to register all vcpus
> past the online ones and thus fail to register the idle driver.
> This is because cpuidle_add_sysfs() will return with -ENODEV as a
> consequence from get_cpu_device() return no device for a non-existing
> CPU.
>
> Instead switch to cpuidle_register_driver() and manually register each
> of the present cpus through cpuhp_setup_state() and future ones that
> get onlined. This mimics similar logic as intel_idle.
>
> Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver")
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Paolo, what do you think?

> ---
>  arch/x86/include/asm/cpuidle_haltpoll.h |  4 +-
>  arch/x86/kernel/kvm.c                   | 18 +++----
>  drivers/cpuidle/cpuidle-haltpoll.c      | 65 +++++++++++++++++++++++--
>  include/linux/cpuidle_haltpoll.h        |  4 +-
>  4 files changed, 70 insertions(+), 21 deletions(-)
>
> diff --git a/arch/x86/include/asm/cpuidle_haltpoll.h b/arch/x86/include/asm/cpuidle_haltpoll.h
> index ff8607d81526..c8b39c6716ff 100644
> --- a/arch/x86/include/asm/cpuidle_haltpoll.h
> +++ b/arch/x86/include/asm/cpuidle_haltpoll.h
> @@ -2,7 +2,7 @@
>  #ifndef _ARCH_HALTPOLL_H
>  #define _ARCH_HALTPOLL_H
>
> -void arch_haltpoll_enable(void);
> -void arch_haltpoll_disable(void);
> +void arch_haltpoll_enable(unsigned int cpu);
> +void arch_haltpoll_disable(unsigned int cpu);
>
>  #endif
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 8d150e3732d9..a9b6c4e2446d 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -880,32 +880,26 @@ static void kvm_enable_host_haltpoll(void *i)
>         wrmsrl(MSR_KVM_POLL_CONTROL, 1);
>  }
>
> -void arch_haltpoll_enable(void)
> +void arch_haltpoll_enable(unsigned int cpu)
>  {
>         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
> -               printk(KERN_ERR "kvm: host does not support poll control\n");
> -               printk(KERN_ERR "kvm: host upgrade recommended\n");
> +               pr_err_once("kvm: host does not support poll control\n");
> +               pr_err_once("kvm: host upgrade recommended\n");
>                 return;
>         }
>
> -       preempt_disable();
>         /* Enable guest halt poll disables host halt poll */
> -       kvm_disable_host_haltpoll(NULL);
> -       smp_call_function(kvm_disable_host_haltpoll, NULL, 1);
> -       preempt_enable();
> +       smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
>  }
>  EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
>
> -void arch_haltpoll_disable(void)
> +void arch_haltpoll_disable(unsigned int cpu)
>  {
>         if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
>                 return;
>
> -       preempt_disable();
>         /* Enable guest halt poll disables host halt poll */
> -       kvm_enable_host_haltpoll(NULL);
> -       smp_call_function(kvm_enable_host_haltpoll, NULL, 1);
> -       preempt_enable();
> +       smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
>  }
>  EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
>  #endif
> diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
> index 9ac093dcbb01..0d1853a7185e 100644
> --- a/drivers/cpuidle/cpuidle-haltpoll.c
> +++ b/drivers/cpuidle/cpuidle-haltpoll.c
> @@ -11,12 +11,15 @@
>   */
>
>  #include <linux/init.h>
> +#include <linux/cpu.h>
>  #include <linux/cpuidle.h>
>  #include <linux/module.h>
>  #include <linux/sched/idle.h>
>  #include <linux/kvm_para.h>
>  #include <linux/cpuidle_haltpoll.h>
>
> +static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;
> +
>  static int default_enter_idle(struct cpuidle_device *dev,
>                               struct cpuidle_driver *drv, int index)
>  {
> @@ -46,6 +49,48 @@ static struct cpuidle_driver haltpoll_driver = {
>         .state_count = 2,
>  };
>
> +static int haltpoll_cpu_online(unsigned int cpu)
> +{
> +       struct cpuidle_device *dev;
> +
> +       dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
> +       if (!dev->registered) {
> +               dev->cpu = cpu;
> +               if (cpuidle_register_device(dev)) {
> +                       pr_notice("cpuidle_register_device %d failed!\n", cpu);
> +                       return -EIO;
> +               }
> +               arch_haltpoll_enable(cpu);
> +       }
> +
> +       return 0;
> +}
> +
> +static void haltpoll_uninit(void)
> +{
> +       unsigned int cpu;
> +
> +       cpus_read_lock();
> +
> +       for_each_online_cpu(cpu) {
> +               struct cpuidle_device *dev =
> +                       per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
> +
> +               if (!dev->registered)
> +                       continue;
> +
> +               arch_haltpoll_disable(cpu);
> +               cpuidle_unregister_device(dev);
> +       }
> +
> +       cpuidle_unregister(&haltpoll_driver);
> +
> +       free_percpu(haltpoll_cpuidle_devices);
> +       haltpoll_cpuidle_devices = NULL;
> +
> +       cpus_read_unlock();
> +}
> +
>  static int __init haltpoll_init(void)
>  {
>         int ret;
> @@ -56,17 +101,27 @@ static int __init haltpoll_init(void)
>         if (!kvm_para_available())
>                 return 0;
>
> -       ret = cpuidle_register(&haltpoll_driver, NULL);
> -       if (ret == 0)
> -               arch_haltpoll_enable();
> +       ret = cpuidle_register_driver(drv);
> +       if (ret < 0)
> +               return ret;
> +
> +       haltpoll_cpuidle_devices = alloc_percpu(struct cpuidle_device);
> +       if (haltpoll_cpuidle_devices == NULL) {
> +               cpuidle_unregister_driver(drv);
> +               return -ENOMEM;
> +       }
> +
> +       ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "idle/haltpoll:online",
> +                               haltpoll_cpu_online, NULL);
> +       if (ret < 0)
> +               haltpoll_uninit();
>
>         return ret;
>  }
>
>  static void __exit haltpoll_exit(void)
>  {
> -       arch_haltpoll_disable();
> -       cpuidle_unregister(&haltpoll_driver);
> +       haltpoll_uninit();
>  }
>
>  module_init(haltpoll_init);
> diff --git a/include/linux/cpuidle_haltpoll.h b/include/linux/cpuidle_haltpoll.h
> index fe5954c2409e..d50c1e0411a2 100644
> --- a/include/linux/cpuidle_haltpoll.h
> +++ b/include/linux/cpuidle_haltpoll.h
> @@ -5,11 +5,11 @@
>  #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
>  #include <asm/cpuidle_haltpoll.h>
>  #else
> -static inline void arch_haltpoll_enable(void)
> +static inline void arch_haltpoll_enable(unsigned int cpu)
>  {
>  }
>
> -static inline void arch_haltpoll_disable(void)
> +static inline void arch_haltpoll_disable(unsigned int cpu)
>  {
>  }
>  #endif
> --
> 2.17.1
>

Re: [PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[Marcelo Tosatti]

Hi Joao,

On Wed, Aug 28, 2019 at 07:56:50PM +0100, Joao Martins wrote:
> When cpus != maxcpus cpuidle-haltpoll will fail to register all vcpus
> past the online ones and thus fail to register the idle driver.
> This is because cpuidle_add_sysfs() will return with -ENODEV as a
> consequence from get_cpu_device() return no device for a non-existing
> CPU.
> 
> Instead switch to cpuidle_register_driver() and manually register each
> of the present cpus through cpuhp_setup_state() and future ones that
> get onlined. This mimics similar logic as intel_idle.
> 
> Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver")
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
>  arch/x86/include/asm/cpuidle_haltpoll.h |  4 +-
>  arch/x86/kernel/kvm.c                   | 18 +++----
>  drivers/cpuidle/cpuidle-haltpoll.c      | 65 +++++++++++++++++++++++--
>  include/linux/cpuidle_haltpoll.h        |  4 +-
>  4 files changed, 70 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cpuidle_haltpoll.h b/arch/x86/include/asm/cpuidle_haltpoll.h
> index ff8607d81526..c8b39c6716ff 100644
> --- a/arch/x86/include/asm/cpuidle_haltpoll.h
> +++ b/arch/x86/include/asm/cpuidle_haltpoll.h
> @@ -2,7 +2,7 @@
>  #ifndef _ARCH_HALTPOLL_H
>  #define _ARCH_HALTPOLL_H
>  
> -void arch_haltpoll_enable(void);
> -void arch_haltpoll_disable(void);
> +void arch_haltpoll_enable(unsigned int cpu);
> +void arch_haltpoll_disable(unsigned int cpu);
>  
>  #endif
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 8d150e3732d9..a9b6c4e2446d 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -880,32 +880,26 @@ static void kvm_enable_host_haltpoll(void *i)
>  	wrmsrl(MSR_KVM_POLL_CONTROL, 1);
>  }
>  
> -void arch_haltpoll_enable(void)
> +void arch_haltpoll_enable(unsigned int cpu)
>  {
>  	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
> -		printk(KERN_ERR "kvm: host does not support poll control\n");
> -		printk(KERN_ERR "kvm: host upgrade recommended\n");
> +		pr_err_once("kvm: host does not support poll control\n");
> +		pr_err_once("kvm: host upgrade recommended\n");
>  		return;
>  	}
>  
> -	preempt_disable();
>  	/* Enable guest halt poll disables host halt poll */
> -	kvm_disable_host_haltpoll(NULL);
> -	smp_call_function(kvm_disable_host_haltpoll, NULL, 1);
> -	preempt_enable();
> +	smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
>  }
>  EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
>  
> -void arch_haltpoll_disable(void)
> +void arch_haltpoll_disable(unsigned int cpu)
>  {
>  	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
>  		return;
>  
> -	preempt_disable();
>  	/* Enable guest halt poll disables host halt poll */
> -	kvm_enable_host_haltpoll(NULL);
> -	smp_call_function(kvm_enable_host_haltpoll, NULL, 1);
> -	preempt_enable();
> +	smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
>  }
>  EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
>  #endif
> diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
> index 9ac093dcbb01..0d1853a7185e 100644
> --- a/drivers/cpuidle/cpuidle-haltpoll.c
> +++ b/drivers/cpuidle/cpuidle-haltpoll.c
> @@ -11,12 +11,15 @@
>   */
>  
>  #include <linux/init.h>
> +#include <linux/cpu.h>
>  #include <linux/cpuidle.h>
>  #include <linux/module.h>
>  #include <linux/sched/idle.h>
>  #include <linux/kvm_para.h>
>  #include <linux/cpuidle_haltpoll.h>
>  
> +static struct cpuidle_device __percpu *haltpoll_cpuidle_devices;
> +
>  static int default_enter_idle(struct cpuidle_device *dev,
>  			      struct cpuidle_driver *drv, int index)
>  {
> @@ -46,6 +49,48 @@ static struct cpuidle_driver haltpoll_driver = {
>  	.state_count = 2,
>  };
>  
> +static int haltpoll_cpu_online(unsigned int cpu)
> +{
> +	struct cpuidle_device *dev;
> +
> +	dev = per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
> +	if (!dev->registered) {
> +		dev->cpu = cpu;
> +		if (cpuidle_register_device(dev)) {
> +			pr_notice("cpuidle_register_device %d failed!\n", cpu);
> +			return -EIO;
> +		}
> +		arch_haltpoll_enable(cpu);
> +	}
> +
> +	return 0;
> +}
> +
> +static void haltpoll_uninit(void)
> +{
> +	unsigned int cpu;
> +
> +	cpus_read_lock();
> +
> +	for_each_online_cpu(cpu) {
> +		struct cpuidle_device *dev =
> +			per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
> +
> +		if (!dev->registered)
> +			continue;
> +
> +		arch_haltpoll_disable(cpu);
> +		cpuidle_unregister_device(dev);
> +	}

1)

> +
> +	cpuidle_unregister(&haltpoll_driver);

cpuidle_unregister_driver.

> +	free_percpu(haltpoll_cpuidle_devices);
> +	haltpoll_cpuidle_devices = NULL;
> +
> +	cpus_read_unlock();

Any reason you can't cpus_read_unlock() at 1) ?

Looks good otherwise.

Thanks!

Re: [PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[Joao Martins]

On 8/29/19 12:56 PM, Marcelo Tosatti wrote:
> Hi Joao,
> 
> On Wed, Aug 28, 2019 at 07:56:50PM +0100, Joao Martins wrote:
>> +static void haltpoll_uninit(void)
>> +{
>> +	unsigned int cpu;
>> +
>> +	cpus_read_lock();
>> +
>> +	for_each_online_cpu(cpu) {
>> +		struct cpuidle_device *dev =
>> +			per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
>> +
>> +		if (!dev->registered)
>> +			continue;
>> +
>> +		arch_haltpoll_disable(cpu);
>> +		cpuidle_unregister_device(dev);
>> +	}
> 
> 1)
> 
>> +
>> +	cpuidle_unregister(&haltpoll_driver);
> 
> cpuidle_unregister_driver.

Will fix -- this was an oversight.

> 
>> +	free_percpu(haltpoll_cpuidle_devices);
>> +	haltpoll_cpuidle_devices = NULL;
>> +
>> +	cpus_read_unlock();
> 
> Any reason you can't cpus_read_unlock() at 1) ?
> 
No, let me adjust that too.

> Looks good otherwise.
> 
> Thanks!
> 
Thanks for the review!

	Joao

Re: [PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[Joao Martins]

On 8/29/19 2:50 PM, Joao Martins wrote:
> On 8/29/19 12:56 PM, Marcelo Tosatti wrote:
>> Hi Joao,
>>
>> On Wed, Aug 28, 2019 at 07:56:50PM +0100, Joao Martins wrote:
>>> +static void haltpoll_uninit(void)
>>> +{
>>> +	unsigned int cpu;
>>> +
>>> +	cpus_read_lock();
>>> +
>>> +	for_each_online_cpu(cpu) {
>>> +		struct cpuidle_device *dev =
>>> +			per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
>>> +
>>> +		if (!dev->registered)
>>> +			continue;
>>> +
>>> +		arch_haltpoll_disable(cpu);
>>> +		cpuidle_unregister_device(dev);
>>> +	}
>>
>> 1)
>>
>>> +
>>> +	cpuidle_unregister(&haltpoll_driver);
>>
>> cpuidle_unregister_driver.
> 
> Will fix -- this was an oversight.
> 
>>
>>> +	free_percpu(haltpoll_cpuidle_devices);
>>> +	haltpoll_cpuidle_devices = NULL;
>>> +
>>> +	cpus_read_unlock();
>>
>> Any reason you can't cpus_read_unlock() at 1) ?
>>
> No, let me adjust that too.
> 
>> Looks good otherwise.
>>

BTW, should I take this as a Acked-by, Reviewed-by, or neither? :)

	Joao

Re: [PATCH v1] cpuidle-haltpoll: vcpu hotplug support

[Marcelo Tosatti]

On Thu, Aug 29, 2019 at 03:24:31PM +0100, Joao Martins wrote:
> On 8/29/19 2:50 PM, Joao Martins wrote:
> > On 8/29/19 12:56 PM, Marcelo Tosatti wrote:
> >> Hi Joao,
> >>
> >> On Wed, Aug 28, 2019 at 07:56:50PM +0100, Joao Martins wrote:
> >>> +static void haltpoll_uninit(void)
> >>> +{
> >>> +	unsigned int cpu;
> >>> +
> >>> +	cpus_read_lock();
> >>> +
> >>> +	for_each_online_cpu(cpu) {
> >>> +		struct cpuidle_device *dev =
> >>> +			per_cpu_ptr(haltpoll_cpuidle_devices, cpu);
> >>> +
> >>> +		if (!dev->registered)
> >>> +			continue;
> >>> +
> >>> +		arch_haltpoll_disable(cpu);
> >>> +		cpuidle_unregister_device(dev);
> >>> +	}
> >>
> >> 1)
> >>
> >>> +
> >>> +	cpuidle_unregister(&haltpoll_driver);
> >>
> >> cpuidle_unregister_driver.
> > 
> > Will fix -- this was an oversight.
> > 
> >>
> >>> +	free_percpu(haltpoll_cpuidle_devices);
> >>> +	haltpoll_cpuidle_devices = NULL;
> >>> +
> >>> +	cpus_read_unlock();
> >>
> >> Any reason you can't cpus_read_unlock() at 1) ?
> >>
> > No, let me adjust that too.
> > 
> >> Looks good otherwise.
> >>
> 
> BTW, should I take this as a Acked-by, Reviewed-by, or neither? :)
> 
> 	Joao

I'll ACK -v2 once you send it.