[PATCH 0/2] ACPI: container hot remove support.

[PATCH 0/2] ACPI: container hot remove support.

[Tang Chen]

Hi,

The container hotplug handler container_notify_cb() didn't implement
the hot-remove functionality. So, these 2 patches implement it like
the following way:

patch 1. Do not use kacpid_wq/kacpid_notify_wq to handle container hotplug event,
         use kacpi_hotplug_wq instead to avoid deadlock.
         Doing this is to reuse acpi_bus_hot_remove_device() in container
         hot-remove handling.

patch 2. Introduce a new function container_device_remove() to handle
         ACPI_NOTIFY_EJECT_REQUEST event for container.


In __acpi_os_execute(), we have the following comments:

        We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
        because the hotplug code may call driver .remove() functions,
        which invoke flush_scheduled_work/acpi_os_wait_events_complete
        to flush these workqueues.

Actually, I run into the deadlock caused by running hotplug code in
kacpid_wq/kacpid_notify_wq. And I'm not quite sure if I did the right
thing in patch1. So, please give some comments if you have a better idea.


This is based on Lu Yinghai's job.
git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-pci-split-pci-root-hp-2

Tang Chen (2):
  Use kacpi_hotplug_wq to handle container hotplug event.
  Container hot remove support.

 drivers/acpi/container.c |  102 +++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 92 insertions(+), 10 deletions(-)

[PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

[Tang Chen]

As the comments in __acpi_os_execute() said:

	We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
	because the hotplug code may call driver .remove() functions,
	which invoke flush_scheduled_work/acpi_os_wait_events_complete
	to flush these workqueues.

we should keep the hotplug code in kacpi_hotplug_wq.

But we have the following call series in kernel now:
	acpi_ev_queue_notify_request()
	|--> acpi_os_execute()
	     |--> __acpi_os_execute(type, function, context, 0)

The last parameter 0 makes the container_notify_cb() executed in
kacpi_notify_wq or kacpid_wq. So, we need to put the real hotplug code
into kacpi_hotplug_wq.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
 drivers/acpi/container.c |   44 +++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 43 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
index 1f9f7d7..643657a 100644
--- a/drivers/acpi/container.c
+++ b/drivers/acpi/container.c
@@ -72,8 +72,36 @@ static struct acpi_driver acpi_container_driver = {
 		},
 };
 
+struct acpi_container_hp_work {
+	struct work_struct work;
+	acpi_handle handle;
+	u32 type;
+	void *context;
+};
+
 /*******************************************************************/
 
+static void alloc_acpi_container_hp_work(acpi_handle handle, u32 type,
+					void *context,
+					void (*func)(struct work_struct *work))
+{
+	struct acpi_container_hp_work *hp_work;
+	int ret;
+
+	hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
+	if (!hp_work)
+		return;
+
+	hp_work->handle = handle;
+	hp_work->type = type;
+	hp_work->context = context;
+
+	INIT_WORK(&hp_work->work, func);
+	ret = queue_work(kacpi_hotplug_wq, &hp_work->work);
+	if (!ret)
+		kfree(hp_work);
+}
+
 static int is_device_present(acpi_handle handle)
 {
 	acpi_handle temp;
@@ -152,14 +180,21 @@ static int container_device_add(struct acpi_device **device, acpi_handle handle)
 	return result;
 }
 
-static void container_notify_cb(acpi_handle handle, u32 type, void *context)
+static void __container_notify_cb(struct work_struct *work)
 {
 	struct acpi_device *device = NULL;
 	int result;
 	int present;
 	acpi_status status;
+	struct acpi_container_hp_work *hp_work;
+	acpi_handle handle;
+	u32 type;
 	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
 
+	hp_work = container_of(work, struct acpi_container_hp_work, work);
+	handle = hp_work->handle;
+	type = hp_work->type;
+
 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		/* Fall through */
@@ -211,6 +246,13 @@ static void container_notify_cb(acpi_handle handle, u32 type, void *context)
 	return;
 }
 
+static void container_notify_cb(acpi_handle handle, u32 type,
+				void *context)
+{
+	alloc_acpi_container_hp_work(handle, type, context,
+				__container_notify_cb);
+}
+
 static acpi_status
 container_walk_namespace_cb(acpi_handle handle,
 			    u32 lvl, void *context, void **rv)
-- 
1.7.1

[PATCH 2/2] Improve container_notify_cb() to support container hot-remove.

[Tang Chen]

This patch introduces a new function container_device_remove() to do
the container hot-remove job. It works like the following:

1. call acpi_bus_trim(device, 0) to stop the container device.
2. generate the KOBJ_OFFLINE uevent. (Did I do this correct ?)
3. call acpi_bus_hot_remove_device(), which will call acpi_bus_trim(device, 1)
   to remove the container.

This patch is based on Lu Yinghai's work.
git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-pci-split-pci-root-hp-2

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
 drivers/acpi/container.c |   58 ++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
index 643657a..1de4672 100644
--- a/drivers/acpi/container.c
+++ b/drivers/acpi/container.c
@@ -180,6 +180,35 @@ static int container_device_add(struct acpi_device **device, acpi_handle handle)
 	return result;
 }
 
+static int container_device_remove(struct acpi_device *device)
+{
+	int ret;
+	struct acpi_eject_event *ej_event;
+
+	ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
+	if (!ej_event)
+		return -ENOMEM;
+
+	ej_event->device = device;
+	ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
+
+	/* stop container device at first */
+	ret = acpi_bus_trim(device, 0);
+	printk(KERN_WARNING "acpi_bus_trim stop return %x\n", ret);
+	if (ret)
+		return ret;
+
+	/* event originated from ACPI eject notification */
+	device->flags.eject_pending = 1;
+
+	/* send the uevent before remove the device */
+	kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
+
+	acpi_bus_hot_remove_device(ej_event);
+
+	return 0;
+}
+
 static void __container_notify_cb(struct work_struct *work)
 {
 	struct acpi_device *device = NULL;
@@ -195,6 +224,9 @@ static void __container_notify_cb(struct work_struct *work)
 	handle = hp_work->handle;
 	type = hp_work->type;
 
+	present = is_device_present(handle);
+	status = acpi_bus_get_device(handle, &device);
+
 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		/* Fall through */
@@ -203,13 +235,14 @@ static void __container_notify_cb(struct work_struct *work)
 		       (type == ACPI_NOTIFY_BUS_CHECK) ?
 		       "ACPI_NOTIFY_BUS_CHECK" : "ACPI_NOTIFY_DEVICE_CHECK");
 
-		present = is_device_present(handle);
-		status = acpi_bus_get_device(handle, &device);
 		if (!present) {
 			if (ACPI_SUCCESS(status)) {
 				/* device exist and this is a remove request */
-				device->flags.eject_pending = 1;
-				kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
+				result = container_device_remove(device);
+				if (result) {
+					printk(KERN_WARNING "Failed to remove container\n");
+					break;
+				}
 				return;
 			}
 			break;
@@ -229,12 +262,19 @@ static void __container_notify_cb(struct work_struct *work)
 		break;
 
 	case ACPI_NOTIFY_EJECT_REQUEST:
-		if (!acpi_bus_get_device(handle, &device) && device) {
-			device->flags.eject_pending = 1;
-			kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
-			return;
+		printk(KERN_WARNING "Container driver received %s event\n",
+			"ACPI_NOTIFY_EJECT_REQUEST");
+
+		if (!present || ACPI_FAILURE(status) || !device)
+			break;
+
+		result = container_device_remove(device);
+		if (result) {
+			printk(KERN_WARNING "Failed to remove container\n");
+			break;
 		}
-		break;
+
+		return;
 
 	default:
 		/* non-hotplug event; possibly handled by other handler */
-- 
1.7.1

Re: [PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

[Yinghai Lu]

On Tue, Oct 23, 2012 at 6:10 AM, Tang Chen <tangchen@cn.fujitsu.com> wrote:
> As the comments in __acpi_os_execute() said:
>
>         We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
>         because the hotplug code may call driver .remove() functions,
>         which invoke flush_scheduled_work/acpi_os_wait_events_complete
>         to flush these workqueues.
>
> we should keep the hotplug code in kacpi_hotplug_wq.
>
> But we have the following call series in kernel now:
>         acpi_ev_queue_notify_request()
>         |--> acpi_os_execute()
>              |--> __acpi_os_execute(type, function, context, 0)
>
> The last parameter 0 makes the container_notify_cb() executed in
> kacpi_notify_wq or kacpid_wq. So, we need to put the real hotplug code
> into kacpi_hotplug_wq.

I had other patches that merge acpi_hp_work in acpiphp and pci_root_hp.

I just put them in to for-pci-split-pci-root-hp-2.

can you check them to see if you can use it?

Thanks

Yinghai

Re: [PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

[Toshi Kani]

On Tue, 2012-10-23 at 21:10 +0800, Tang Chen wrote:
> As the comments in __acpi_os_execute() said:
> 
> 	We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
> 	because the hotplug code may call driver .remove() functions,
> 	which invoke flush_scheduled_work/acpi_os_wait_events_complete
> 	to flush these workqueues.
> 
> we should keep the hotplug code in kacpi_hotplug_wq.
> 
> But we have the following call series in kernel now:
> 	acpi_ev_queue_notify_request()
> 	|--> acpi_os_execute()
> 	     |--> __acpi_os_execute(type, function, context, 0)
> 
> The last parameter 0 makes the container_notify_cb() executed in
> kacpi_notify_wq or kacpid_wq. So, we need to put the real hotplug code
> into kacpi_hotplug_wq.

Hi Tang,

I am curious; is there a particular reason why you use
alloc_acpi_container_hp_work() instead of acpi_os_hotplug_execute(),
which is already there in the tree?

Thanks,
-Toshi


> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
> ---
>  drivers/acpi/container.c |   44 +++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 43 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
> index 1f9f7d7..643657a 100644
> --- a/drivers/acpi/container.c
> +++ b/drivers/acpi/container.c
> @@ -72,8 +72,36 @@ static struct acpi_driver acpi_container_driver = {
>  		},
>  };
>  
> +struct acpi_container_hp_work {
> +	struct work_struct work;
> +	acpi_handle handle;
> +	u32 type;
> +	void *context;
> +};
> +
>  /*******************************************************************/
>  
> +static void alloc_acpi_container_hp_work(acpi_handle handle, u32 type,
> +					void *context,
> +					void (*func)(struct work_struct *work))
> +{
> +	struct acpi_container_hp_work *hp_work;
> +	int ret;
> +
> +	hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
> +	if (!hp_work)
> +		return;
> +
> +	hp_work->handle = handle;
> +	hp_work->type = type;
> +	hp_work->context = context;
> +
> +	INIT_WORK(&hp_work->work, func);
> +	ret = queue_work(kacpi_hotplug_wq, &hp_work->work);
> +	if (!ret)
> +		kfree(hp_work);
> +}
> +
>  static int is_device_present(acpi_handle handle)
>  {
>  	acpi_handle temp;
> @@ -152,14 +180,21 @@ static int container_device_add(struct acpi_device **device, acpi_handle handle)
>  	return result;
>  }
>  
> -static void container_notify_cb(acpi_handle handle, u32 type, void *context)
> +static void __container_notify_cb(struct work_struct *work)
>  {
>  	struct acpi_device *device = NULL;
>  	int result;
>  	int present;
>  	acpi_status status;
> +	struct acpi_container_hp_work *hp_work;
> +	acpi_handle handle;
> +	u32 type;
>  	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
>  
> +	hp_work = container_of(work, struct acpi_container_hp_work, work);
> +	handle = hp_work->handle;
> +	type = hp_work->type;
> +
>  	switch (type) {
>  	case ACPI_NOTIFY_BUS_CHECK:
>  		/* Fall through */
> @@ -211,6 +246,13 @@ static void container_notify_cb(acpi_handle handle, u32 type, void *context)
>  	return;
>  }
>  
> +static void container_notify_cb(acpi_handle handle, u32 type,
> +				void *context)
> +{
> +	alloc_acpi_container_hp_work(handle, type, context,
> +				__container_notify_cb);
> +}
> +
>  static acpi_status
>  container_walk_namespace_cb(acpi_handle handle,
>  			    u32 lvl, void *context, void **rv)

Re: [PATCH 1/2] Use kacpi_hotplug_wq to handle container hotplug event.

[Tang Chen]

On 10/25/2012 01:33 AM, Toshi Kani wrote:
> On Tue, 2012-10-23 at 21:10 +0800, Tang Chen wrote:
>> As the comments in __acpi_os_execute() said:
>>
>> 	We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq
>> 	because the hotplug code may call driver .remove() functions,
>> 	which invoke flush_scheduled_work/acpi_os_wait_events_complete
>> 	to flush these workqueues.
>>
>> we should keep the hotplug code in kacpi_hotplug_wq.
>>
>> But we have the following call series in kernel now:
>> 	acpi_ev_queue_notify_request()
>> 	|-->  acpi_os_execute()
>> 	     |-->  __acpi_os_execute(type, function, context, 0)
>>
>> The last parameter 0 makes the container_notify_cb() executed in
>> kacpi_notify_wq or kacpid_wq. So, we need to put the real hotplug code
>> into kacpi_hotplug_wq.
>
> Hi Tang,
>
> I am curious; is there a particular reason why you use
> alloc_acpi_container_hp_work() instead of acpi_os_hotplug_execute(),
> which is already there in the tree?

Hi Toshi,

Thanks for telling me this. I didn't realize this function. :)
And yes, it is better.

Thanks. :)

>
> Thanks,
> -Toshi
>
>
>> Signed-off-by: Tang Chen<tangchen@cn.fujitsu.com>
>> ---
>>   drivers/acpi/container.c |   44 +++++++++++++++++++++++++++++++++++++++++++-
>>   1 files changed, 43 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
>> index 1f9f7d7..643657a 100644
>> --- a/drivers/acpi/container.c
>> +++ b/drivers/acpi/container.c
>> @@ -72,8 +72,36 @@ static struct acpi_driver acpi_container_driver = {
>>   		},
>>   };
>>
>> +struct acpi_container_hp_work {
>> +	struct work_struct work;
>> +	acpi_handle handle;
>> +	u32 type;
>> +	void *context;
>> +};
>> +
>>   /*******************************************************************/
>>
>> +static void alloc_acpi_container_hp_work(acpi_handle handle, u32 type,
>> +					void *context,
>> +					void (*func)(struct work_struct *work))
>> +{
>> +	struct acpi_container_hp_work *hp_work;
>> +	int ret;
>> +
>> +	hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
>> +	if (!hp_work)
>> +		return;
>> +
>> +	hp_work->handle = handle;
>> +	hp_work->type = type;
>> +	hp_work->context = context;
>> +
>> +	INIT_WORK(&hp_work->work, func);
>> +	ret = queue_work(kacpi_hotplug_wq,&hp_work->work);
>> +	if (!ret)
>> +		kfree(hp_work);
>> +}
>> +
>>   static int is_device_present(acpi_handle handle)
>>   {
>>   	acpi_handle temp;
>> @@ -152,14 +180,21 @@ static int container_device_add(struct acpi_device **device, acpi_handle handle)
>>   	return result;
>>   }
>>
>> -static void container_notify_cb(acpi_handle handle, u32 type, void *context)
>> +static void __container_notify_cb(struct work_struct *work)
>>   {
>>   	struct acpi_device *device = NULL;
>>   	int result;
>>   	int present;
>>   	acpi_status status;
>> +	struct acpi_container_hp_work *hp_work;
>> +	acpi_handle handle;
>> +	u32 type;
>>   	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
>>
>> +	hp_work = container_of(work, struct acpi_container_hp_work, work);
>> +	handle = hp_work->handle;
>> +	type = hp_work->type;
>> +
>>   	switch (type) {
>>   	case ACPI_NOTIFY_BUS_CHECK:
>>   		/* Fall through */
>> @@ -211,6 +246,13 @@ static void container_notify_cb(acpi_handle handle, u32 type, void *context)
>>   	return;
>>   }
>>
>> +static void container_notify_cb(acpi_handle handle, u32 type,
>> +				void *context)
>> +{
>> +	alloc_acpi_container_hp_work(handle, type, context,
>> +				__container_notify_cb);
>> +}
>> +
>>   static acpi_status
>>   container_walk_namespace_cb(acpi_handle handle,
>>   			    u32 lvl, void *context, void **rv)
>
>
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