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Groups > linux.kernel > #1528713

Re: [PATCH 12/20] net/iucv: Convert to hotplug state machine

From Ursula Braun <ubraun@linux.vnet.ibm.com>
Newsgroups linux.kernel
Subject Re: [PATCH 12/20] net/iucv: Convert to hotplug state machine
Date 2016-11-23 20:40 +0100
Message-ID <sGLyF-Aw-17@gated-at.bofh.it> (permalink)
References <sEzLj-4lB-7@gated-at.bofh.it> <sEzLk-4lB-55@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Sebastian,

your patch looks good to me. I run successfully some small tests with it.
I want to suggest a small change in iucv_init() to keep the uniform technique
of undo labels below. Do you agree?

Kind regards, Ursula

On 11/17/2016 07:35 PM, Sebastian Andrzej Siewior wrote:
> Install the callbacks via the state machine and let the core invoke the
> callbacks on the already online CPUs. The smp function calls in the
> online/downprep callbacks are not required as the callback is guaranteed to
> be invoked on the upcoming/outgoing cpu.
> 
> Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-s390@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  include/linux/cpuhotplug.h |   1 +
>  net/iucv/iucv.c            | 118 +++++++++++++++++----------------------------
>  2 files changed, 45 insertions(+), 74 deletions(-)
> 
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index fd5598b8353a..69abf2c09f6c 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -63,6 +63,7 @@ enum cpuhp_state {
>  	CPUHP_X86_THERM_PREPARE,
>  	CPUHP_X86_CPUID_PREPARE,
>  	CPUHP_X86_MSR_PREPARE,
> +	CPUHP_NET_IUCV_PREPARE,
>  	CPUHP_TIMERS_DEAD,
>  	CPUHP_NOTF_ERR_INJ_PREPARE,
>  	CPUHP_MIPS_SOC_PREPARE,
> diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
> index 88a2a3ba4212..f0d6afc5d4a9 100644
> --- a/net/iucv/iucv.c
> +++ b/net/iucv/iucv.c
> @@ -639,7 +639,7 @@ static void iucv_disable(void)
>  	put_online_cpus();
>  }
>  
> -static void free_iucv_data(int cpu)
> +static int iucv_cpu_dead(unsigned int cpu)
>  {
>  	kfree(iucv_param_irq[cpu]);
>  	iucv_param_irq[cpu] = NULL;
> @@ -647,9 +647,10 @@ static void free_iucv_data(int cpu)
>  	iucv_param[cpu] = NULL;
>  	kfree(iucv_irq_data[cpu]);
>  	iucv_irq_data[cpu] = NULL;
> +	return 0;
>  }
>  
> -static int alloc_iucv_data(int cpu)
> +static int iucv_cpu_prepare(unsigned int cpu)
>  {
>  	/* Note: GFP_DMA used to get memory below 2G */
>  	iucv_irq_data[cpu] = kmalloc_node(sizeof(struct iucv_irq_data),
> @@ -671,58 +672,38 @@ static int alloc_iucv_data(int cpu)
>  	return 0;
>  
>  out_free:
> -	free_iucv_data(cpu);
> +	iucv_cpu_dead(cpu);
>  	return -ENOMEM;
>  }
>  
> -static int iucv_cpu_notify(struct notifier_block *self,
> -				     unsigned long action, void *hcpu)
> +static int iucv_cpu_online(unsigned int cpu)
>  {
> -	cpumask_t cpumask;
> -	long cpu = (long) hcpu;
> -
> -	switch (action) {
> -	case CPU_UP_PREPARE:
> -	case CPU_UP_PREPARE_FROZEN:
> -		if (alloc_iucv_data(cpu))
> -			return notifier_from_errno(-ENOMEM);
> -		break;
> -	case CPU_UP_CANCELED:
> -	case CPU_UP_CANCELED_FROZEN:
> -	case CPU_DEAD:
> -	case CPU_DEAD_FROZEN:
> -		free_iucv_data(cpu);
> -		break;
> -	case CPU_ONLINE:
> -	case CPU_ONLINE_FROZEN:
> -	case CPU_DOWN_FAILED:
> -	case CPU_DOWN_FAILED_FROZEN:
> -		if (!iucv_path_table)
> -			break;
> -		smp_call_function_single(cpu, iucv_declare_cpu, NULL, 1);
> -		break;
> -	case CPU_DOWN_PREPARE:
> -	case CPU_DOWN_PREPARE_FROZEN:
> -		if (!iucv_path_table)
> -			break;
> -		cpumask_copy(&cpumask, &iucv_buffer_cpumask);
> -		cpumask_clear_cpu(cpu, &cpumask);
> -		if (cpumask_empty(&cpumask))
> -			/* Can't offline last IUCV enabled cpu. */
> -			return notifier_from_errno(-EINVAL);
> -		smp_call_function_single(cpu, iucv_retrieve_cpu, NULL, 1);
> -		if (cpumask_empty(&iucv_irq_cpumask))
> -			smp_call_function_single(
> -				cpumask_first(&iucv_buffer_cpumask),
> -				iucv_allow_cpu, NULL, 1);
> -		break;
> -	}
> -	return NOTIFY_OK;
> +	if (!iucv_path_table)
> +		return 0;
> +	iucv_declare_cpu(NULL);
> +	return 0;
>  }
>  
> -static struct notifier_block __refdata iucv_cpu_notifier = {
> -	.notifier_call = iucv_cpu_notify,
> -};
> +static int iucv_cpu_down_prep(unsigned int cpu)
> +{
> +	cpumask_t cpumask;
> +
> +	if (!iucv_path_table)
> +		return 0;
> +
> +	cpumask_copy(&cpumask, &iucv_buffer_cpumask);
> +	cpumask_clear_cpu(cpu, &cpumask);
> +	if (cpumask_empty(&cpumask))
> +		/* Can't offline last IUCV enabled cpu. */
> +		return -EINVAL;
> +
> +	iucv_retrieve_cpu(NULL);
> +	if (!cpumask_empty(&iucv_irq_cpumask))
> +		return 0;
> +	smp_call_function_single(cpumask_first(&iucv_buffer_cpumask),
> +				 iucv_allow_cpu, NULL, 1);
> +	return 0;
> +}
>  
>  /**
>   * iucv_sever_pathid
> @@ -2027,6 +2008,7 @@ struct iucv_interface iucv_if = {
>  };
>  EXPORT_SYMBOL(iucv_if);
>  
> +static enum cpuhp_state iucv_online;
>  /**
>   * iucv_init
>   *
> @@ -2035,7 +2017,6 @@ EXPORT_SYMBOL(iucv_if);
>  static int __init iucv_init(void)
>  {
>  	int rc;
> -	int cpu;
>  
>  	if (!MACHINE_IS_VM) {
>  		rc = -EPROTONOSUPPORT;
> @@ -2054,23 +2035,19 @@ static int __init iucv_init(void)
>  		goto out_int;
>  	}
>  
> -	cpu_notifier_register_begin();
> -
> -	for_each_online_cpu(cpu) {
> -		if (alloc_iucv_data(cpu)) {
> -			rc = -ENOMEM;
> -			goto out_free;
> -		}
> -	}
> -	rc = __register_hotcpu_notifier(&iucv_cpu_notifier);
> +	rc = cpuhp_setup_state(CPUHP_NET_IUCV_PREPARE, "net/iucv:prepare",
> +			       iucv_cpu_prepare, iucv_cpu_dead);
>  	if (rc)
>  		goto out_free;
> -
> -	cpu_notifier_register_done();
> +	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "net/iucv:online",
> +			       iucv_cpu_online, iucv_cpu_down_prep);
> +	if (rc < 0)
> +		goto out_free;
> +	iucv_online = rc;
>  
>  	rc = register_reboot_notifier(&iucv_reboot_notifier);
>  	if (rc)
> -		goto out_cpu;
> +		goto out_free;
>  	ASCEBC(iucv_error_no_listener, 16);
>  	ASCEBC(iucv_error_no_memory, 16);
>  	ASCEBC(iucv_error_pathid, 16);
> @@ -2084,14 +2061,10 @@ static int __init iucv_init(void)
>  
>  out_reboot:
>  	unregister_reboot_notifier(&iucv_reboot_notifier);
> -out_cpu:
> -	cpu_notifier_register_begin();
> -	__unregister_hotcpu_notifier(&iucv_cpu_notifier);
>  out_free:
> -	for_each_possible_cpu(cpu)
> -		free_iucv_data(cpu);
> -
> -	cpu_notifier_register_done();
> +	if (iucv_online)
> +		cpuhp_remove_state(iucv_online);
> +	cpuhp_remove_state(CPUHP_NET_IUCV_PREPARE);
>  
>  	root_device_unregister(iucv_root);
>  out_int:
I prefer to keep the technique of cascaded undo labels here, like this:
@@ -2054,23 +2035,19 @@ static int __init iucv_init(void)
                goto out_int;
        }
 
-       cpu_notifier_register_begin();
-
-       for_each_online_cpu(cpu) {
-               if (alloc_iucv_data(cpu)) {
-                       rc = -ENOMEM;
-                       goto out_free;
-               }
-       }
-       rc = __register_hotcpu_notifier(&iucv_cpu_notifier);
+       rc = cpuhp_setup_state(CPUHP_NET_IUCV_PREPARE, "net/iucv:prepare",
+                              iucv_cpu_prepare, iucv_cpu_dead);
        if (rc)
-               goto out_free;
-
-       cpu_notifier_register_done();
+               goto out_dev;
+       rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "net/iucv:online",
+                              iucv_cpu_online, iucv_cpu_down_prep);
+       if (rc < 0)
+               goto out_prep;
+       iucv_online = rc;
 
        rc = register_reboot_notifier(&iucv_reboot_notifier);
        if (rc)
-               goto out_cpu;
+               goto out_remove;
        ASCEBC(iucv_error_no_listener, 16);
        ASCEBC(iucv_error_no_memory, 16);
        ASCEBC(iucv_error_pathid, 16);
@@ -2084,15 +2061,12 @@ static int __init iucv_init(void)
 
 out_reboot:
        unregister_reboot_notifier(&iucv_reboot_notifier);
-out_cpu:
-       cpu_notifier_register_begin();
-       __unregister_hotcpu_notifier(&iucv_cpu_notifier);
-out_free:
-       for_each_possible_cpu(cpu)
-               free_iucv_data(cpu);
-
-       cpu_notifier_register_done();
-
+out_remove:
+       if (iucv_online)
+               cpuhp_remove_state(iucv_online);
+out_prep:
+       cpuhp_remove_state(CPUHP_NET_IUCV_PREPARE);
+out_dev:
        root_device_unregister(iucv_root);
 out_int:
        unregister_external_irq(EXT_IRQ_IUCV, iucv_external_interrupt);

> @@ -2110,7 +2083,6 @@ static int __init iucv_init(void)
>  static void __exit iucv_exit(void)
>  {
>  	struct iucv_irq_list *p, *n;
> -	int cpu;
>  
>  	spin_lock_irq(&iucv_queue_lock);
>  	list_for_each_entry_safe(p, n, &iucv_task_queue, list)
> @@ -2119,11 +2091,9 @@ static void __exit iucv_exit(void)
>  		kfree(p);
>  	spin_unlock_irq(&iucv_queue_lock);
>  	unregister_reboot_notifier(&iucv_reboot_notifier);
> -	cpu_notifier_register_begin();
> -	__unregister_hotcpu_notifier(&iucv_cpu_notifier);
> -	for_each_possible_cpu(cpu)
> -		free_iucv_data(cpu);
> -	cpu_notifier_register_done();
> +
> +	cpuhp_remove_state_nocalls(iucv_online);
> +	cpuhp_remove_state(CPUHP_NET_IUCV_PREPARE);
>  	root_device_unregister(iucv_root);
>  	bus_unregister(&iucv_bus);
>  	unregister_external_irq(EXT_IRQ_IUCV, iucv_external_interrupt);
> 

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Thread

cpu hotplug: convert more drivers (batch #5) Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
  [PATCH 12/20] net/iucv: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] net/iucv: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] net/iucv: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-23 00:20 +0100
    Re: [PATCH 12/20] net/iucv: Convert to hotplug state machine Ursula Braun <ubraun@linux.vnet.ibm.com> - 2016-11-23 20:40 +0100
      Re: [PATCH 12/20] net/iucv: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-24 10:20 +0100
        [PATCH 12/20 v2] net/iucv: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-24 15:20 +0100
          [PATCH] net/iucv: use explicit clean up labels in iucv_init() Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-24 17:20 +0100
            [tip:smp/hotplug] net/iucv: Use explicit clean up labels in  iucv_init() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-24 21:00 +0100
  [PATCH 09/20] powercap/intel rapl: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] powercap/intel rapl: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
  [PATCH 19/20] x86/oprofile/nmi: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] x86/oprofile/nmi: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] x86/oprofile/nmi: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 14/20] arm/bL_switcher: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] arm/bL_switcher: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] arm/bL_switcher: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 13/20] sched/nohz: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] sched/nohz: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] sched/nohz: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-23 00:20 +0100
  [PATCH 16/20] powerpc/sysfs: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] powerpc/sysfs: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] powerpc/sysfs: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 10/20] powercap/intel_rapl: Cleanup duplicated init code Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] powercap/intel_rapl: Cleanup duplicated init code tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-11-21 17:00 +0100
  [PATCH 01/20] x86/mce/therm_throt: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] x86/mce/therm_throt: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 16:50 +0100
    [tip:smp/hotplug] x86/mce/therm_throt: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 07/20] pci/xgene-msi: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] PCI/xgene-msi: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 16:50 +0100
    [tip:smp/hotplug] PCI/xgene-msi: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-23 00:20 +0100
  [PATCH 06/20] hwmon/via-cputemp: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [PATCH 06/20 v2] hwmon/via-cputemp: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-18 16:20 +0100
    Re: [PATCH 06/20] hwmon/via-cputemp: Convert to hotplug state machine Guenter Roeck <linux@roeck-us.net> - 2016-11-23 16:40 +0100
  [PATCH 05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    Re: [05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Guenter Roeck <linux@roeck-us.net> - 2016-11-19 18:30 +0100
      Re: [05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-20 00:00 +0100
        Re: [05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Guenter Roeck <linux@roeck-us.net> - 2016-11-20 05:00 +0100
          Re: [05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-20 21:40 +0100
  [PATCH 08/20] powercap/intel_rapl: Add missing domain data update on hotplug Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] powercap/intel_rapl: Add missing domain data  update on hotplug tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-11-21 16:50 +0100
  [PATCH 03/20] x86/msr: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] x86/msr: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 16:50 +0100
    [tip:smp/hotplug] x86/msr: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100

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