[PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock

[PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock

[Xie XiuQi]

I meet a deadlock during cpu hotplug. The code path is bellow:

Call Trace:
 [<ffffffff816e373c>] dump_stack+0x19/0x1b
 [<ffffffff810fd85a>] validate_chain.isra.43+0xf4a/0x1120
 [<ffffffff810236c9>] ? sched_clock+0x9/0x10
 [<ffffffff810ca8bd>] ? sched_clock_local+0x1d/0x80
 [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
 [<ffffffff810fe846>] __lock_acquire+0x3c6/0xb70
 [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
 [<ffffffff810ff7e2>] lock_acquire+0xa2/0x1f0
 [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
 [<ffffffff816e7a14>] mutex_lock_nested+0x94/0x3f0
 [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
 [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
 [<ffffffff810fe0fd>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffff813ba132>] acpi_scan_is_offline+0x2c/0xa3	--> LOCK (DEADLOCK)
 [<ffffffff813fdac8>] acpi_container_offline+0x32/0x4e
 [<ffffffff81469e59>] container_offline+0x19/0x20
 [<ffffffff81462955>] device_offline+0x95/0xc0
 [<ffffffff813b9e53>] acpi_bus_offline+0xbc/0x126	--> LOCK
 [<ffffffff813bb83d>] acpi_device_hotplug+0x236/0x46b
 [<ffffffff813b4c75>] acpi_hotplug_work_fn+0x1e/0x29
 [<ffffffff810a6c10>] process_one_work+0x220/0x710
 [<ffffffff810a6ba4>] ? process_one_work+0x1b4/0x710
 [<ffffffff810a721b>] worker_thread+0x11b/0x3a0
 [<ffffffff810a7100>] ? process_one_work+0x710/0x710
 [<ffffffff810b061d>] kthread+0xed/0x100
 [<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80
 [<ffffffff816f663c>] ret_from_fork+0x7c/0xb0
 [<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80

This deadlock was introduced by commit caa73ea
("ACPI / hotplug / driver core: Handle containers in a special way").

In this patch, we just introduced a lockless version __acpi_scan_is_offline()
for acpi_container_offline(), to avoid this deadlock.

Cc: <stable@vger.kernel.org> # v3.14+
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
---
 drivers/acpi/container.c |  2 +-
 drivers/acpi/internal.h  |  1 +
 drivers/acpi/scan.c      | 15 ++++++++++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
index c8ead9f..43bda3b2 100644
--- a/drivers/acpi/container.c
+++ b/drivers/acpi/container.c
@@ -50,7 +50,7 @@ static int acpi_container_offline(struct container_dev *cdev)
 
 	/* Check all of the dependent devices' physical companions. */
 	list_for_each_entry(child, &adev->children, node)
-		if (!acpi_scan_is_offline(child, false))
+		if (!__acpi_scan_is_offline(child, false))
 			return -EBUSY;
 
 	return 0;
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 56b321a..3b7a07b 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -80,6 +80,7 @@ void acpi_apd_init(void);
 acpi_status acpi_hotplug_schedule(struct acpi_device *adev, u32 src);
 bool acpi_queue_hotplug_work(struct work_struct *work);
 void acpi_device_hotplug(struct acpi_device *adev, u32 src);
+bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
 bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
 
 /* --------------------------------------------------------------------------
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index bbca783..ea55a9a 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -293,13 +293,12 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha
 }
 static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
 
-bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
+/* Must be called under physical_node_lock. */
+bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
 {
 	struct acpi_device_physical_node *pn;
 	bool offline = true;
 
-	mutex_lock(&adev->physical_node_lock);
-
 	list_for_each_entry(pn, &adev->physical_node_list, node)
 		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
 			if (uevent)
@@ -309,7 +308,17 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
 			break;
 		}
 
+	return offline;
+}
+
+bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
+{
+	bool offline = true;
+
+	mutex_lock(&adev->physical_node_lock);
+	offline = __acpi_scan_is_offline(adev, uevent);
 	mutex_unlock(&adev->physical_node_lock);
+
 	return offline;
 }
 
-- 
1.8.3.1

[PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock

[Xie XiuQi]

I meet a deadlock during cpu hotplug. The code path is bellow:

Call Trace:
 [<ffffffff816e373c>] dump_stack+0x19/0x1b
 [<ffffffff810fd85a>] validate_chain.isra.43+0xf4a/0x1120
 [<ffffffff810236c9>] ? sched_clock+0x9/0x10
 [<ffffffff810ca8bd>] ? sched_clock_local+0x1d/0x80
 [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
 [<ffffffff810fe846>] __lock_acquire+0x3c6/0xb70
 [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
 [<ffffffff810ff7e2>] lock_acquire+0xa2/0x1f0
 [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
 [<ffffffff816e7a14>] mutex_lock_nested+0x94/0x3f0
 [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
 [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
 [<ffffffff810fe0fd>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffff813ba132>] acpi_scan_is_offline+0x2c/0xa3	--> LOCK (DEADLOCK)
 [<ffffffff813fdac8>] acpi_container_offline+0x32/0x4e
 [<ffffffff81469e59>] container_offline+0x19/0x20
 [<ffffffff81462955>] device_offline+0x95/0xc0
 [<ffffffff813b9e53>] acpi_bus_offline+0xbc/0x126	--> LOCK
 [<ffffffff813bb83d>] acpi_device_hotplug+0x236/0x46b
 [<ffffffff813b4c75>] acpi_hotplug_work_fn+0x1e/0x29
 [<ffffffff810a6c10>] process_one_work+0x220/0x710
 [<ffffffff810a6ba4>] ? process_one_work+0x1b4/0x710
 [<ffffffff810a721b>] worker_thread+0x11b/0x3a0
 [<ffffffff810a7100>] ? process_one_work+0x710/0x710
 [<ffffffff810b061d>] kthread+0xed/0x100
 [<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80
 [<ffffffff816f663c>] ret_from_fork+0x7c/0xb0
 [<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80

This deadlock was introduced by commit caa73ea
("ACPI / hotplug / driver core: Handle containers in a special way").

In this patch, we just introduced a lockless version __acpi_scan_is_offline()
for acpi_container_offline(), to avoid this deadlock.

Cc: <stable@vger.kernel.org> # v3.14+
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
---
 drivers/acpi/container.c |  2 +-
 drivers/acpi/internal.h  |  1 +
 drivers/acpi/scan.c      | 15 ++++++++++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
index c8ead9f..43bda3b2 100644
--- a/drivers/acpi/container.c
+++ b/drivers/acpi/container.c
@@ -50,7 +50,7 @@ static int acpi_container_offline(struct container_dev *cdev)
 
 	/* Check all of the dependent devices' physical companions. */
 	list_for_each_entry(child, &adev->children, node)
-		if (!acpi_scan_is_offline(child, false))
+		if (!__acpi_scan_is_offline(child, false))
 			return -EBUSY;
 
 	return 0;
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 56b321a..3b7a07b 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -80,6 +80,7 @@ void acpi_apd_init(void);
 acpi_status acpi_hotplug_schedule(struct acpi_device *adev, u32 src);
 bool acpi_queue_hotplug_work(struct work_struct *work);
 void acpi_device_hotplug(struct acpi_device *adev, u32 src);
+bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
 bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
 
 /* --------------------------------------------------------------------------
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index bbca783..ea55a9a 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -293,13 +293,12 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha
 }
 static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
 
-bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
+/* Must be called under physical_node_lock. */
+bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
 {
 	struct acpi_device_physical_node *pn;
 	bool offline = true;
 
-	mutex_lock(&adev->physical_node_lock);
-
 	list_for_each_entry(pn, &adev->physical_node_list, node)
 		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
 			if (uevent)
@@ -309,7 +308,17 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
 			break;
 		}
 
+	return offline;
+}
+
+bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
+{
+	bool offline = true;
+
+	mutex_lock(&adev->physical_node_lock);
+	offline = __acpi_scan_is_offline(adev, uevent);
 	mutex_unlock(&adev->physical_node_lock);
+
 	return offline;
 }
 
-- 
1.8.3.1

Re: [PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock

[Rafael J. Wysocki]

On Tuesday, April 07, 2015 05:03:12 PM Xie XiuQi wrote:
> I meet a deadlock during cpu hotplug. The code path is bellow:
> 
> Call Trace:
>  [<ffffffff816e373c>] dump_stack+0x19/0x1b
>  [<ffffffff810fd85a>] validate_chain.isra.43+0xf4a/0x1120
>  [<ffffffff810236c9>] ? sched_clock+0x9/0x10
>  [<ffffffff810ca8bd>] ? sched_clock_local+0x1d/0x80
>  [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
>  [<ffffffff810fe846>] __lock_acquire+0x3c6/0xb70
>  [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
>  [<ffffffff810ff7e2>] lock_acquire+0xa2/0x1f0
>  [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
>  [<ffffffff816e7a14>] mutex_lock_nested+0x94/0x3f0
>  [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
>  [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
>  [<ffffffff810fe0fd>] ? trace_hardirqs_on+0xd/0x10
>  [<ffffffff813ba132>] acpi_scan_is_offline+0x2c/0xa3	--> LOCK (DEADLOCK)

Is it the same device, actually?  acpi_container_offline() walks the *children*
of the container while acpi_bus_offline() locks the container itself.

Is it not the case?

>  [<ffffffff813fdac8>] acpi_container_offline+0x32/0x4e
>  [<ffffffff81469e59>] container_offline+0x19/0x20
>  [<ffffffff81462955>] device_offline+0x95/0xc0
>  [<ffffffff813b9e53>] acpi_bus_offline+0xbc/0x126	--> LOCK
>  [<ffffffff813bb83d>] acpi_device_hotplug+0x236/0x46b
>  [<ffffffff813b4c75>] acpi_hotplug_work_fn+0x1e/0x29
>  [<ffffffff810a6c10>] process_one_work+0x220/0x710
>  [<ffffffff810a6ba4>] ? process_one_work+0x1b4/0x710
>  [<ffffffff810a721b>] worker_thread+0x11b/0x3a0
>  [<ffffffff810a7100>] ? process_one_work+0x710/0x710
>  [<ffffffff810b061d>] kthread+0xed/0x100
>  [<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80
>  [<ffffffff816f663c>] ret_from_fork+0x7c/0xb0
>  [<ffffffff810b0530>] ? insert_kthread_work+0x80/0x80
> 
> This deadlock was introduced by commit caa73ea
> ("ACPI / hotplug / driver core: Handle containers in a special way").
> 
> In this patch, we just introduced a lockless version __acpi_scan_is_offline()
> for acpi_container_offline(), to avoid this deadlock.

So why is this a correct approach?  Why can acpi_container_offline() suddenly
call __acpi_scan_is_offline() without the lock?

> Cc: <stable@vger.kernel.org> # v3.14+
> Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
> ---
>  drivers/acpi/container.c |  2 +-
>  drivers/acpi/internal.h  |  1 +
>  drivers/acpi/scan.c      | 15 ++++++++++++---
>  3 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c
> index c8ead9f..43bda3b2 100644
> --- a/drivers/acpi/container.c
> +++ b/drivers/acpi/container.c
> @@ -50,7 +50,7 @@ static int acpi_container_offline(struct container_dev *cdev)
>  
>  	/* Check all of the dependent devices' physical companions. */
>  	list_for_each_entry(child, &adev->children, node)
> -		if (!acpi_scan_is_offline(child, false))
> +		if (!__acpi_scan_is_offline(child, false))
>  			return -EBUSY;
>  
>  	return 0;
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 56b321a..3b7a07b 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -80,6 +80,7 @@ void acpi_apd_init(void);
>  acpi_status acpi_hotplug_schedule(struct acpi_device *adev, u32 src);
>  bool acpi_queue_hotplug_work(struct work_struct *work);
>  void acpi_device_hotplug(struct acpi_device *adev, u32 src);
> +bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
>  bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
>  
>  /* --------------------------------------------------------------------------
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index bbca783..ea55a9a 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -293,13 +293,12 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha
>  }
>  static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
>  
> -bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
> +/* Must be called under physical_node_lock. */
> +bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
>  {
>  	struct acpi_device_physical_node *pn;
>  	bool offline = true;
>  
> -	mutex_lock(&adev->physical_node_lock);
> -
>  	list_for_each_entry(pn, &adev->physical_node_list, node)
>  		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
>  			if (uevent)
> @@ -309,7 +308,17 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
>  			break;
>  		}
>  
> +	return offline;
> +}
> +
> +bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
> +{
> +	bool offline = true;
> +
> +	mutex_lock(&adev->physical_node_lock);
> +	offline = __acpi_scan_is_offline(adev, uevent);
>  	mutex_unlock(&adev->physical_node_lock);
> +
>  	return offline;
>  }
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock

[Rafael J. Wysocki]

On Tuesday, April 07, 2015 01:22:52 PM Rafael J. Wysocki wrote:
> On Tuesday, April 07, 2015 05:03:12 PM Xie XiuQi wrote:
> > I meet a deadlock during cpu hotplug. The code path is bellow:
> > 
> > Call Trace:
> >  [<ffffffff816e373c>] dump_stack+0x19/0x1b
> >  [<ffffffff810fd85a>] validate_chain.isra.43+0xf4a/0x1120
> >  [<ffffffff810236c9>] ? sched_clock+0x9/0x10
> >  [<ffffffff810ca8bd>] ? sched_clock_local+0x1d/0x80
> >  [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
> >  [<ffffffff810fe846>] __lock_acquire+0x3c6/0xb70
> >  [<ffffffff810caa88>] ? sched_clock_cpu+0xa8/0x100
> >  [<ffffffff810ff7e2>] lock_acquire+0xa2/0x1f0
> >  [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
> >  [<ffffffff816e7a14>] mutex_lock_nested+0x94/0x3f0
> >  [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
> >  [<ffffffff813ba132>] ? acpi_scan_is_offline+0x2c/0xa3
> >  [<ffffffff810fe0fd>] ? trace_hardirqs_on+0xd/0x10
> >  [<ffffffff813ba132>] acpi_scan_is_offline+0x2c/0xa3	--> LOCK (DEADLOCK)
> 
> Is it the same device, actually?  acpi_container_offline() walks the *children*
> of the container while acpi_bus_offline() locks the container itself.

So the patch below should make the splat go away too if I'm not mistaken.

---
 drivers/acpi/scan.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
 	struct acpi_device_physical_node *pn;
 	bool offline = true;
 
-	mutex_lock(&adev->physical_node_lock);
+	/*
+	 * acpi_container_offline() calls this for all of the container's
+	 * children under the container's physical_node_lock lock.
+	 */
+	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
 
 	list_for_each_entry(pn, &adev->physical_node_list, node)
 		if (device_supports_offline(pn->dev) && !pn->dev->offline) {

[PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

acpi_scan_is_offline() may be called under the physical_node_lock
of the given device object's parent, so prevent lockdep from
complaining about that by annotating that instance with
SINGLE_DEPTH_NESTING.

Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/scan.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
 	struct acpi_device_physical_node *pn;
 	bool offline = true;
 
-	mutex_lock(&adev->physical_node_lock);
+	/*
+	 * acpi_container_offline() calls this for all of the container's
+	 * children under the container's physical_node_lock lock.
+	 */
+	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
 
 	list_for_each_entry(pn, &adev->physical_node_list, node)
 		if (device_supports_offline(pn->dev) && !pn->dev->offline) {

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Xie XiuQi]

On 2015/4/11 7:31, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> acpi_scan_is_offline() may be called under the physical_node_lock
> of the given device object's parent, so prevent lockdep from
> complaining about that by annotating that instance with
> SINGLE_DEPTH_NESTING.
> 
> Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Thank you for your patch, I'll test soon.

Thanks,
Xie XiuQi

> ---
>  drivers/acpi/scan.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
>  	struct acpi_device_physical_node *pn;
>  	bool offline = true;
>  
> -	mutex_lock(&adev->physical_node_lock);
> +	/*
> +	 * acpi_container_offline() calls this for all of the container's
> +	 * children under the container's physical_node_lock lock.
> +	 */
> +	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
>  
>  	list_for_each_entry(pn, &adev->physical_node_list, node)
>  		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
> 
> 
> .
> 

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Xie XiuQi]

On 2015/4/11 7:31, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> acpi_scan_is_offline() may be called under the physical_node_lock
> of the given device object's parent, so prevent lockdep from
> complaining about that by annotating that instance with
> SINGLE_DEPTH_NESTING.
> 
> Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Thank you for your patch, I'll test soon.

Thanks,
Xie XiuQi

> ---
>  drivers/acpi/scan.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
>  	struct acpi_device_physical_node *pn;
>  	bool offline = true;
>  
> -	mutex_lock(&adev->physical_node_lock);
> +	/*
> +	 * acpi_container_offline() calls this for all of the container's
> +	 * children under the container's physical_node_lock lock.
> +	 */
> +	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
>  
>  	list_for_each_entry(pn, &adev->physical_node_list, node)
>  		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
> 
> 
> .
> 

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Hanjun Guo]

On 2015年04月11日 07:31, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> acpi_scan_is_offline() may be called under the physical_node_lock
> of the given device object's parent, so prevent lockdep from
> complaining about that by annotating that instance with
> SINGLE_DEPTH_NESTING.

I think this is trigged by setting acpi_force_hot_remove to 1,
in acpi_scan_hot_remove():

         if (device->handler && device->handler->hotplug.demand_offline
             && !acpi_force_hot_remove) {
                 if (!acpi_scan_is_offline(device, true))
                         return -EBUSY;
         } else {
                 int error = acpi_scan_try_to_offline(device);
                 if (error)
                         return error;
         }

then the container device will be removed by acpi_scan_try_to_offline(),
let's wait for Xiuqi's test result.

Thanks
Hanjun

>
> Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>   drivers/acpi/scan.c |    6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
>   	struct acpi_device_physical_node *pn;
>   	bool offline = true;
>
> -	mutex_lock(&adev->physical_node_lock);
> +	/*
> +	 * acpi_container_offline() calls this for all of the container's
> +	 * children under the container's physical_node_lock lock.
> +	 */
> +	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
>
>   	list_for_each_entry(pn, &adev->physical_node_list, node)
>   		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
>

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Rafael J. Wysocki]

On Monday, April 13, 2015 04:27:16 PM Hanjun Guo wrote:
> On 2015年04月11日 07:31, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > acpi_scan_is_offline() may be called under the physical_node_lock
> > of the given device object's parent, so prevent lockdep from
> > complaining about that by annotating that instance with
> > SINGLE_DEPTH_NESTING.
> 
> I think this is trigged by setting acpi_force_hot_remove to 1,
> in acpi_scan_hot_remove():
> 
>          if (device->handler && device->handler->hotplug.demand_offline
>              && !acpi_force_hot_remove) {
>                  if (!acpi_scan_is_offline(device, true))
>                          return -EBUSY;
>          } else {
>                  int error = acpi_scan_try_to_offline(device);
>                  if (error)
>                          return error;
>          }
> 
> then the container device will be removed by acpi_scan_try_to_offline(),
> let's wait for Xiuqi's test result.

I'm not sure what you mean.  demand_offline is 'true' for containers, so
acpi_force_hot_remove doesn't matter here.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Rafael J. Wysocki]

On Monday, April 13, 2015 04:27:16 PM Hanjun Guo wrote:
> On 2015年04月11日 07:31, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > acpi_scan_is_offline() may be called under the physical_node_lock
> > of the given device object's parent, so prevent lockdep from
> > complaining about that by annotating that instance with
> > SINGLE_DEPTH_NESTING.
> 
> I think this is trigged by setting acpi_force_hot_remove to 1,
> in acpi_scan_hot_remove():
> 
>          if (device->handler && device->handler->hotplug.demand_offline
>              && !acpi_force_hot_remove) {
>                  if (!acpi_scan_is_offline(device, true))
>                          return -EBUSY;
>          } else {
>                  int error = acpi_scan_try_to_offline(device);
>                  if (error)
>                          return error;
>          }
> 
> then the container device will be removed by acpi_scan_try_to_offline(),
> let's wait for Xiuqi's test result.

I'm not sure what you mean.  demand_offline is 'true' for containers, so
acpi_force_hot_remove doesn't matter here.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Toshi Kani]

On Sat, 2015-04-11 at 01:31 +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> acpi_scan_is_offline() may be called under the physical_node_lock
> of the given device object's parent, so prevent lockdep from
> complaining about that by annotating that instance with
> SINGLE_DEPTH_NESTING.
> 
> Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Agreed that the issue is likely with the lock-class.  Assuming Xie's
test goes well (we will need to wait for that :),

Reviewed-by: Toshi Kani <toshi.kani@hp.com>

Thanks,
-Toshi

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Xie XiuQi]

On 2015/4/11 7:31, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> acpi_scan_is_offline() may be called under the physical_node_lock
> of the given device object's parent, so prevent lockdep from
> complaining about that by annotating that instance with
> SINGLE_DEPTH_NESTING.
> 
> Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Tested-by: Xie XiuQi <xiexiuqi@huawei.com>

Thanks,
Xie XiuQi

> ---
>  drivers/acpi/scan.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
>  	struct acpi_device_physical_node *pn;
>  	bool offline = true;
>  
> -	mutex_lock(&adev->physical_node_lock);
> +	/*
> +	 * acpi_container_offline() calls this for all of the container's
> +	 * children under the container's physical_node_lock lock.
> +	 */
> +	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
>  
>  	list_for_each_entry(pn, &adev->physical_node_list, node)
>  		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
> 
> 
> .
> 

Re: [PATCH] ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline()

[Xie XiuQi]

On 2015/4/11 7:31, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> acpi_scan_is_offline() may be called under the physical_node_lock
> of the given device object's parent, so prevent lockdep from
> complaining about that by annotating that instance with
> SINGLE_DEPTH_NESTING.
> 
> Reported-by: Xie XiuQi <xiexiuqi@huawei.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Tested-by: Xie XiuQi <xiexiuqi@huawei.com>

Thanks,
Xie XiuQi

> ---
>  drivers/acpi/scan.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de
>  	struct acpi_device_physical_node *pn;
>  	bool offline = true;
>  
> -	mutex_lock(&adev->physical_node_lock);
> +	/*
> +	 * acpi_container_offline() calls this for all of the container's
> +	 * children under the container's physical_node_lock lock.
> +	 */
> +	mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);
>  
>  	list_for_each_entry(pn, &adev->physical_node_list, node)
>  		if (device_supports_offline(pn->dev) && !pn->dev->offline) {
> 
> 
> .
>