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ACPI: New eject flow to remove devices cautiously

PATCH Superseded Chester Lin 2 participants 6 messages May 31, 2019 – Jun 3, 2019

Subsystems (3)
ACPI Driver core ACPI component architecture (acpica)

v1 of 2 Superseded Latest is v2 →

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Chester Lin

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#0 lore raw

cover ACPI: New eject flow to remove devices cautiously

Currently there are two ways to handle ACPI device ejection. When an eject event happens on a container, the kernel just sends KOBJ_CHANGE to userland and userland should handle offline operation. For other device types, acpi_scan_try_to_offline() is called and it tries to put target device(s) offline and then removes all nodes once they are all offline.

However we found that sometimes applications could intensively access resources on ejectable devices therefore they could have risk if ejection suddenly happens and removes devices without any notification. In stead of executing the offline callbakcs directly, we want to introduce a new approach, which sends change events to notify all target nodes beforehand and hands over offline handling to userland so that userland can have a chance to schedule an offline task based on current workload. The online function to recover from failure is also changed, it follows the same approach to send change events rather than putting devices online directly , which means userland will also need to take care of online handling.

To ensure that eject function can work properly since normal users might not have their own offline/online handling, we will submit a generic udev rule to systemd upstream as default in order to deal with change events and take [offline/online] action accordingly. But the Hot-Removing part still remains so the hotplug function can run to it once target nodes are all offline.

To easily monitor eject status and start over an eject process, there's a status trace mechanism in this eject flow, which helps to count current online devices under the ejectable target, and it can reschedule an eject event when all nodes within the device tree have been put offline.

Chester Lin (3):
ACPI / hotplug: Send change events for offline/online requests when
eject is triggered
ACPI / hotplug: Eject status trace and auto-remove approach ACPI / device_sysfs: Add eject show attr to monitor eject status

 drivers/acpi/container.c    |   2 +-
 drivers/acpi/device_sysfs.c |  20 ++-
 drivers/acpi/glue.c         |  81 ++++++++++
 drivers/acpi/internal.h     |  31 +++-
 drivers/acpi/scan.c         | 298 ++++++++++++++++++++++++++----------
 drivers/base/core.c         |   2 +
 include/acpi/acpi_bus.h     |   3 +-
 7 files changed, 356 insertions(+), 81 deletions(-)
Signature · 1 line
2.20.1
author
#1 lore raw

PATCH 1/3 ACPI / hotplug: Send change events for offline/online requests when eject is triggered

Here we change offline/online handling in device hotplug by sending change events to userland as notification so that userland can have control and determine when will be a good time to put them offline/online based on current workload. In this approach the real offline/online opertions are handed over to userland so that userland can have more time to prepare before any device change actually happens.

All child devices under the ejection target are traversed and notified hierarchically based on ACPI namespace in ascending order when an eject event happens.

Signed-off-by Chester Lin <[email protected]>
---
 drivers/acpi/container.c |   2 +-
 drivers/acpi/internal.h  |   2 +-
 drivers/acpi/scan.c      | 140 +++++++++++++++++----------------------
 include/acpi/acpi_bus.h  |   2 +-
 4 files changed, 65 insertions(+), 81 deletions(-)
drivers/acpi/container.c +1 -1
index 12c240903c18..f8c7768b4c8e 100644
@@ -46,7 +46,7 @@ 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))
 			return -EBUSY;
 
 	return 0;
drivers/acpi/internal.h +1 -1
index 6eaf06db7752..47014776fecb 100644
@@ -92,7 +92,7 @@ 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);
 
 acpi_status acpi_sysfs_table_handler(u32 event, void *table, void *context);
 void acpi_scan_table_handler(u32 event, void *table, void *context);
drivers/acpi/scan.c +62 -78

210 lines not on this page · raw message

include/acpi/acpi_bus.h +1 -1
index 52d4375bde9d..2ad8262f2a47 100644
@@ -343,7 +343,7 @@ struct acpi_device_physical_node {
 	unsigned int node_id;
 	struct list_head node;
 	struct device *dev;
-	bool put_online:1;
+	bool changed_offline:1;
 };
 
 struct acpi_device_properties {
Signature · 1 line
2.20.1
author
#2 lore raw

PATCH 2/3 ACPI / hotplug: Eject status trace and auto-remove approach

In reply to Chester Lin

This is an eject-status trace mechanism which helps to count current online devices under the ejection target, and it can automatically reschedules an eject event when all related devices are offline. The number of online nodes can be updated when any node has been put offline successfully. Any online event within the whole device tree during ejection will stop the whole process and devices who have been put offline will need be online again as recovery.

Signed-off-by Chester Lin <[email protected]>
---
 drivers/acpi/glue.c     |  81 +++++++++++++++++++++++
 drivers/acpi/internal.h |  28 ++++++++
 drivers/acpi/scan.c     | 139 +++++++++++++++++++++++++++++++++++++++-
 drivers/base/core.c     |   2 +
 include/acpi/acpi_bus.h |   1 +
 5 files changed, 248 insertions(+), 3 deletions(-)
drivers/acpi/glue.c +81 -0
index edd10b3c7ec8..50745b12ae84 100644
@@ -361,6 +361,81 @@ static int acpi_device_notify_remove(struct device *dev)
 	return 0;
 }
 
+static void acpi_device_eject_tracer(struct device *dev,
+				enum kobject_action action)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+	struct acpi_device *adev_root = NULL;
+	struct eject_data *eject_node = NULL;
+	struct eject_data *eject_root = NULL;
+
+	if (!adev || !adev->eject_stat)
+		return;
+
+	acpi_scan_lock_acquire();
+
+	eject_node = (struct eject_data *)adev->eject_stat;
+
+	if (eject_node->base.root_handle)
+		adev_root =
+		    acpi_bus_get_acpi_device(eject_node->base.root_handle);
+
+	if (adev_root)
+		eject_root = (struct eject_data *)adev_root->eject_stat;
+
+	if (action == KOBJ_OFFLINE) {
+		/*
+		 * If the offline device is child, update its eject_root's
+		 * number of online nodes.
+		 */
+		if (eject_root) {
+			if (eject_root->online_nodes)
+				eject_root->online_nodes--;
+
+			if (eject_root->online_nodes <=
+			    adev_root->physical_node_count)
+				acpi_eject_retry(adev_root);
+
+			goto tracer_end;
+		}
+		/*
+		 * Adjust number of online nodes when any physical node under
+		 * eject_root is offline. Trigger acpi_eject_try() once all
+		 * nodes are offline.
+		 */
+		if (eject_node->online_nodes)
+			eject_node->online_nodes--;
+
+		if (!eject_node->online_nodes)
+			acpi_eject_retry(adev);
+
+	} else if (action == KOBJ_ONLINE) {
+		/* !eject_root means now eject_node is root */
+		if (!eject_root)
+			eject_root = eject_node;
+
+		if (eject_root->status == ACPI_EJECT_STATUS_GOING_OFFLINE) {
+			eject_root->status = ACPI_EJECT_STATUS_FAIL;
+			acpi_eject_retry(adev_root);
+		}
+	}
+tracer_end:
+	if (adev_root)
+		acpi_bus_put_acpi_device(adev_root);
+
+	acpi_scan_lock_release();
+}
+
+static inline void acpi_device_check_eject_status(struct device *dev)
+{
+	acpi_device_eject_tracer(dev, KOBJ_OFFLINE);
+}
+
+static inline void acpi_device_check_eject_recover(struct device *dev)
+{
+	acpi_device_eject_tracer(dev, KOBJ_ONLINE);
+}
+
 int acpi_platform_notify(struct device *dev, enum kobject_action action)
 {
 	switch (action) {

@@ -370,6 +445,12 @@ int acpi_platform_notify(struct device *dev, enum kobject_action action)
 	case KOBJ_REMOVE:
 		acpi_device_notify_remove(dev);
 		break;
+	case KOBJ_OFFLINE:
+		acpi_device_check_eject_status(dev);
+		break;
+	case KOBJ_ONLINE:
+		acpi_device_check_eject_recover(dev);
+		break;
 	default:
 		break;
 	}
drivers/acpi/internal.h +28 -0
index 47014776fecb..0dcec4243b23 100644
@@ -266,4 +266,32 @@ void acpi_init_lpit(void);
 static inline void acpi_init_lpit(void) { }
 #endif
 
+/* --------------------------------------------------------------------------
+ *				Eject Status
+ * --------------------------------------------------------------------------
+ */
+enum acpi_eject_status {
+	ACPI_EJECT_STATUS_NONE = 0,
+	ACPI_EJECT_STATUS_GOING_OFFLINE,
+	ACPI_EJECT_STATUS_FAIL
+};
+
+enum acpi_eject_node_type {
+	ACPI_EJECT_CHILD_NODE = 0,
+	ACPI_EJECT_ROOT_NODE
+};
+
+struct eject_data_base {
+	enum acpi_eject_node_type type;
+	acpi_handle root_handle;
+};
+
+struct eject_data {
+	struct eject_data_base base;
+	enum acpi_eject_status status;
+	u32 online_nodes;
+};
+
+void acpi_eject_retry(struct acpi_device *adev);
+
 #endif /* _ACPI_INTERNAL_H_ */
drivers/acpi/scan.c +136 -3

199 lines not on this page · raw message

drivers/base/core.c +2 -0
index fd7511e04e62..aca6976ed19b 100644
@@ -2542,6 +2542,7 @@ int device_offline(struct device *dev)
 			if (!ret) {
 				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
 				dev->offline = true;
+				device_platform_notify(dev, KOBJ_OFFLINE);
 			}
 		}
 	}

@@ -2571,6 +2572,7 @@ int device_online(struct device *dev)
 			if (!ret) {
 				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
 				dev->offline = false;
+				device_platform_notify(dev, KOBJ_ONLINE);
 			}
 		} else {
 			ret = 1;
include/acpi/acpi_bus.h +1 -0
index 2ad8262f2a47..f587bd1ca6ba 100644
@@ -391,6 +391,7 @@ struct acpi_device {
 	struct list_head physical_node_list;
 	struct mutex physical_node_lock;
 	void (*remove)(struct acpi_device *);
+	void *eject_stat;
 };
 
 /* Non-device subnode */
Signature · 1 line
2.20.1
author
#3 lore raw

PATCH 3/3 ACPI / device_sysfs: Add eject show attr to monitor eject status

In reply to Chester Lin

An acpi_eject_show attribute for users to monitor current status because sometimes it might take time to finish an ejection so we need to know whether it is still in progress or not.

Signed-off-by Chester Lin <[email protected]>
---
 drivers/acpi/device_sysfs.c | 20 +++++++++++++++++++-
 drivers/acpi/internal.h     |  1 +
 drivers/acpi/scan.c         | 27 +++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
drivers/acpi/device_sysfs.c +19 -1
index 78c2653bf020..70b22eec6bbc 100644
@@ -403,7 +403,25 @@ acpi_eject_store(struct device *d, struct device_attribute *attr,
 	return status == AE_NO_MEMORY ? -ENOMEM : -EAGAIN;
 }
 
-static DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);
+static ssize_t acpi_eject_show(struct device *d,
+				struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_device = to_acpi_device(d);
+	acpi_object_type not_used;
+	acpi_status status;
+
+	if ((!acpi_device->handler || !acpi_device->handler->hotplug.enabled)
+	    && !acpi_device->driver)
+		return -ENODEV;
+
+	status = acpi_get_type(acpi_device->handle, &not_used);
+	if (ACPI_FAILURE(status) || !acpi_device->flags.ejectable)
+		return -ENODEV;
+
+	return sprintf(buf, "%s\n", acpi_eject_status_string(acpi_device));
+}
+
+static DEVICE_ATTR(eject, 0644, acpi_eject_show, acpi_eject_store);
 
 static ssize_t
 acpi_device_hid_show(struct device *dev, struct device_attribute *attr, char *buf)
drivers/acpi/internal.h +1 -0
index 0dcec4243b23..e7037d68c3d9 100644
@@ -293,5 +293,6 @@ struct eject_data {
 };
 
 void acpi_eject_retry(struct acpi_device *adev);
+char *acpi_eject_status_string(struct acpi_device *adev);
 
 #endif /* _ACPI_INTERNAL_H_ */
drivers/acpi/scan.c +27 -0
index c60110db1cd6..27c4c1148879 100644
@@ -370,6 +370,33 @@ static int acpi_scan_offline_check(struct acpi_device *device)
 	return ret;
 }
 
+char *acpi_eject_status_string(struct acpi_device *adev)
+{
+	struct eject_data *eject_obj;
+	char *status_string = "none";
+
+	mutex_lock(&acpi_scan_lock);
+	eject_obj = (struct eject_data *) adev->eject_stat;
+
+	if (eject_obj) {
+		switch (eject_obj->status) {
+		case ACPI_EJECT_STATUS_NONE:
+			break;
+		case ACPI_EJECT_STATUS_GOING_OFFLINE:
+			status_string = "going offline";
+			break;
+		case ACPI_EJECT_STATUS_FAIL:
+			status_string = "failure";
+			break;
+		default:
+			status_string = "(unknown)";
+		}
+	}
+
+	mutex_unlock(&acpi_scan_lock);
+	return status_string;
+}
+
 static int acpi_scan_hot_remove(struct acpi_device *device)
 {
 	acpi_handle handle = device->handle;
Signature · 1 line
2.20.1
maintainer
#4 lore raw

Re: [PATCH 3/3] ACPI / device_sysfs: Add eject show attr to monitor eject status

Quoted 29 lines · Chester Lin

An acpi_eject_show attribute for users to monitor current status because sometimes it might take time to finish an ejection so we need to know whether it is still in progress or not.

Signed-off-by Chester Lin <[email protected]>
---
 drivers/acpi/device_sysfs.c | 20 +++++++++++++++++++-
 drivers/acpi/internal.h     |  1 +
 drivers/acpi/scan.c         | 27 +++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
drivers/acpi/device_sysfs.c +9 -1
index 78c2653bf020..70b22eec6bbc 100644
@@ -403,7 +403,25 @@ acpi_eject_store(struct device *d, struct device_attribute *attr,
 	return status == AE_NO_MEMORY ? -ENOMEM : -EAGAIN;
 }
 
-static DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);
+static ssize_t acpi_eject_show(struct device *d,
+				struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_device = to_acpi_device(d);
+	acpi_object_type not_used;
+	acpi_status status;
+
+	if ((!acpi_device->handler || !acpi_device->handler->hotplug.enabled)
+	    && !acpi_device->driver)

drivers/acpi/device_sysfs.c acpi_eject_store(struct device *d, struct device_attribute *attr, · line 424

Quoted 10 lines
drivers/acpi/device_sysfs.c +10 -0
+		return -ENODEV;
+
+	status = acpi_get_type(acpi_device->handle, &not_used);
+	if (ACPI_FAILURE(status) || !acpi_device->flags.ejectable)
+		return -ENODEV;
+
+	return sprintf(buf, "%s\n", acpi_eject_status_string(acpi_device));
+}
+
+static DEVICE_ATTR(eject, 0644, acpi_eject_show, acpi_eject_store);

DEVICE_ATTR_RW()?

And you need to document the new sysfs file in Documentation/ABI/

thanks,

greg k-h

author
#5 lore raw

Re: [PATCH 3/3] ACPI / device_sysfs: Add eject show attr to monitor eject status

Quoted 43 lines · Greg KH
Quoted 29 lines · Chester Lin

An acpi_eject_show attribute for users to monitor current status because sometimes it might take time to finish an ejection so we need to know whether it is still in progress or not.

Signed-off-by Chester Lin <[email protected]>
---
 drivers/acpi/device_sysfs.c | 20 +++++++++++++++++++-
 drivers/acpi/internal.h     |  1 +
 drivers/acpi/scan.c         | 27 +++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
drivers/acpi/device_sysfs.c +9 -1
index 78c2653bf020..70b22eec6bbc 100644
@@ -403,7 +403,25 @@ acpi_eject_store(struct device *d, struct device_attribute *attr,
 	return status == AE_NO_MEMORY ? -ENOMEM : -EAGAIN;
 }
 
-static DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);
+static ssize_t acpi_eject_show(struct device *d,
+				struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_device = to_acpi_device(d);
+	acpi_object_type not_used;
+	acpi_status status;
+
+	if ((!acpi_device->handler || !acpi_device->handler->hotplug.enabled)
+	    && !acpi_device->driver)

drivers/acpi/device_sysfs.c acpi_eject_store(struct device *d, struct device_attribute *attr, · line 424

Quoted 10 lines
drivers/acpi/device_sysfs.c +10 -0
+		return -ENODEV;
+
+	status = acpi_get_type(acpi_device->handle, &not_used);
+	if (ACPI_FAILURE(status) || !acpi_device->flags.ejectable)
+		return -ENODEV;
+
+	return sprintf(buf, "%s\n", acpi_eject_status_string(acpi_device));
+}
+
+static DEVICE_ATTR(eject, 0644, acpi_eject_show, acpi_eject_store);

DEVICE_ATTR_RW()?

Quoted 6 lines

And you need to document the new sysfs file in Documentation/ABI/

thanks,

greg k-h

Hi Greg,

Thank you for the reminder and I will fix these two in v2.

Regards,
Chester