[PATCH 10/25] s390/smp: Make cpu notifier symetric

[PATCH 10/25] s390/smp: Make cpu notifier symetric

[Sebastian Andrzej Siewior]

From: Thomas Gleixner <tglx@linutronix.de>

There is no reason to remove the sysfs cpu files when the CPU is dead, they
can be removed when the cpu is prepared to go down. Doing it at
DOWN_PREPARE allows us to convert it to a symetric hotplug state in the
next step.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 arch/s390/kernel/smp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 35531fe1c5ea..1a21e66c484a 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -1056,9 +1056,10 @@ static int smp_cpu_notify(struct notifier_block *self, unsigned long action,
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_ONLINE:
+	case CPU_DOWN_FAILED:
 		err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
 		break;
-	case CPU_DEAD:
+	case CPU_DOWN_PREPARE::
 		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
 		break;
 	}
-- 
2.10.2

[PATCH 11/25] s390/smp: Convert to hotplug state machine

[Sebastian Andrzej Siewior]

cpuhp_setup_state() invokes the startup callback on all online cpus with
the proper protection, so we can remove the cpu hotplug protection from the
init function and the creation of the per cpu files for online cpus in
smp_add_present_cpu(). smp_add_present_cpu() is called also called from
__smp_rescan_cpus(), but this callpath never adds an online cpu, it merily
adds newly present cpus, so the creation of the cpu files is not required.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/s390/kernel/smp.c | 38 ++++++++++++--------------------------
 1 file changed, 12 insertions(+), 26 deletions(-)

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 1a21e66c484a..b613aa989e40 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -1047,23 +1047,18 @@ static struct attribute_group cpu_online_attr_group = {
 	.attrs = cpu_online_attrs,
 };
 
-static int smp_cpu_notify(struct notifier_block *self, unsigned long action,
-			  void *hcpu)
+static int smp_cpu_online(unsigned int cpu)
 {
-	unsigned int cpu = (unsigned int)(long)hcpu;
 	struct device *s = &per_cpu(cpu_device, cpu)->dev;
-	int err = 0;
 
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_ONLINE:
-	case CPU_DOWN_FAILED:
-		err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
-		break;
-	case CPU_DOWN_PREPARE::
-		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
-		break;
-	}
-	return notifier_from_errno(err);
+	return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
+}
+static int smp_cpu_pre_down(unsigned int cpu)
+{
+	struct device *s = &per_cpu(cpu_device, cpu)->dev;
+
+	sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
+	return 0;
 }
 
 static int smp_add_present_cpu(int cpu)
@@ -1084,20 +1079,13 @@ static int smp_add_present_cpu(int cpu)
 	rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
 	if (rc)
 		goto out_cpu;
-	if (cpu_online(cpu)) {
-		rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
-		if (rc)
-			goto out_online;
-	}
+
 	rc = topology_cpu_init(c);
 	if (rc)
 		goto out_topology;
 	return 0;
 
 out_topology:
-	if (cpu_online(cpu))
-		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
-out_online:
 	sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
 out_cpu:
 #ifdef CONFIG_HOTPLUG_CPU
@@ -1150,17 +1138,15 @@ static int __init s390_smp_init(void)
 	if (rc)
 		return rc;
 #endif
-	cpu_notifier_register_begin();
 	for_each_present_cpu(cpu) {
 		rc = smp_add_present_cpu(cpu);
 		if (rc)
 			goto out;
 	}
 
-	__hotcpu_notifier(smp_cpu_notify, 0);
-
+	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
+			       smp_cpu_online, smp_cpu_pre_down);
 out:
-	cpu_notifier_register_done();
 	return rc;
 }
 subsys_initcall(s390_smp_init);
-- 
2.10.2

Re: [PATCH 10/25] s390/smp: Make cpu notifier symetric

[Heiko Carstens]

On Thu, Nov 03, 2016 at 03:50:06PM +0100, Sebastian Andrzej Siewior wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> There is no reason to remove the sysfs cpu files when the CPU is dead, they
> can be removed when the cpu is prepared to go down. Doing it at
> DOWN_PREPARE allows us to convert it to a symetric hotplug state in the
> next step.
> 
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: linux-s390@vger.kernel.org
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  arch/s390/kernel/smp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
> index 35531fe1c5ea..1a21e66c484a 100644
> --- a/arch/s390/kernel/smp.c
> +++ b/arch/s390/kernel/smp.c
> @@ -1056,9 +1056,10 @@ static int smp_cpu_notify(struct notifier_block *self, unsigned long action,
>  
>  	switch (action & ~CPU_TASKS_FROZEN) {
>  	case CPU_ONLINE:
> +	case CPU_DOWN_FAILED:
>  		err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
>  		break;
> -	case CPU_DEAD:
> +	case CPU_DOWN_PREPARE::

This won't compile... even though it will be removed with the following
patch it would be good to fix this to keep this bisectable.

Re: [PATCH 11/25] s390/smp: Convert to hotplug state machine

[Heiko Carstens]

On Thu, Nov 03, 2016 at 03:50:07PM +0100, Sebastian Andrzej Siewior wrote:
> @@ -1084,20 +1079,13 @@ static int smp_add_present_cpu(int cpu)
>  	rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
>  	if (rc)
>  		goto out_cpu;
> -	if (cpu_online(cpu)) {
> -		rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
> -		if (rc)
> -			goto out_online;
> -	}
> +
>  	rc = topology_cpu_init(c);

Please don't add whitespace :)

If you fix the minor nits both s390 related patches are
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Thanks!

[PATCH 10/25 v2] s390/smp: Make cpu notifier symetric

[Sebastian Andrzej Siewior]

From: Thomas Gleixner <tglx@linutronix.de>

There is no reason to remove the sysfs cpu files when the CPU is dead, they
can be removed when the cpu is prepared to go down. Doing it at
DOWN_PREPARE allows us to convert it to a symetric hotplug state in the
next step.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v1…v2: s/::/

 arch/s390/kernel/smp.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -1056,9 +1056,10 @@ static int smp_cpu_notify(struct notifie
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_ONLINE:
+	case CPU_DOWN_FAILED:
 		err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
 		break;
-	case CPU_DEAD:
+	case CPU_DOWN_PREPARE:
 		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
 		break;
 	}

[PATCH 11/25 v2] s390/smp: Convert to hotplug state machine

[Sebastian Andrzej Siewior]

cpuhp_setup_state() invokes the startup callback on all online cpus with
the proper protection, so we can remove the cpu hotplug protection from the
init function and the creation of the per cpu files for online cpus in
smp_add_present_cpu(). smp_add_present_cpu() is called also called from
__smp_rescan_cpus(), but this callpath never adds an online cpu, it merily
adds newly present cpus, so the creation of the cpu files is not required.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
v1…v2:
	- removed (or not adding) one empty line
	- rebase on top of the previous patch

 arch/s390/kernel/smp.c |   37 +++++++++++--------------------------
 1 file changed, 11 insertions(+), 26 deletions(-)

--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -1047,23 +1047,18 @@ static struct attribute_group cpu_online
 	.attrs = cpu_online_attrs,
 };
 
-static int smp_cpu_notify(struct notifier_block *self, unsigned long action,
-			  void *hcpu)
+static int smp_cpu_online(unsigned int cpu)
 {
-	unsigned int cpu = (unsigned int)(long)hcpu;
 	struct device *s = &per_cpu(cpu_device, cpu)->dev;
-	int err = 0;
 
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_ONLINE:
-	case CPU_DOWN_FAILED:
-		err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
-		break;
-	case CPU_DOWN_PREPARE:
-		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
-		break;
-	}
-	return notifier_from_errno(err);
+	return sysfs_create_group(&s->kobj, &cpu_online_attr_group);
+}
+static int smp_cpu_pre_down(unsigned int cpu)
+{
+	struct device *s = &per_cpu(cpu_device, cpu)->dev;
+
+	sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
+	return 0;
 }
 
 static int smp_add_present_cpu(int cpu)
@@ -1084,20 +1079,12 @@ static int smp_add_present_cpu(int cpu)
 	rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
 	if (rc)
 		goto out_cpu;
-	if (cpu_online(cpu)) {
-		rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
-		if (rc)
-			goto out_online;
-	}
 	rc = topology_cpu_init(c);
 	if (rc)
 		goto out_topology;
 	return 0;
 
 out_topology:
-	if (cpu_online(cpu))
-		sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
-out_online:
 	sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
 out_cpu:
 #ifdef CONFIG_HOTPLUG_CPU
@@ -1150,17 +1137,15 @@ static int __init s390_smp_init(void)
 	if (rc)
 		return rc;
 #endif
-	cpu_notifier_register_begin();
 	for_each_present_cpu(cpu) {
 		rc = smp_add_present_cpu(cpu);
 		if (rc)
 			goto out;
 	}
 
-	__hotcpu_notifier(smp_cpu_notify, 0);
-
+	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "s390/smp:online",
+			       smp_cpu_online, smp_cpu_pre_down);
 out:
-	cpu_notifier_register_done();
 	return rc;
 }
 subsys_initcall(s390_smp_init);