From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Modify the generic ACPI hotplug code to be able to check if devices
scheduled for hot-removal may be gracefully removed from the system
using the device offline/online mechanism introduced previously.
Namely, make acpi_scan_hot_remove() handling device hot-removal call
device_offline() for all physical companions of the ACPI device nodes
involved in the operation and check the results. If any of the
device_offline() calls fails, the function will not progress to the
removal phase (which cannot be aborted), unless its (new) force
argument is set (in case of a failing offline it will put the devices
offlined by it back online).
In support of 'forced' device hot-removal, add a new sysfs attribute
'force_remove' that will reside under /sys/firmware/acpi/hotplug/.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-firmware-acpi | 10 +++
drivers/acpi/internal.h | 2
drivers/acpi/scan.c | 84 ++++++++++++++++++++++++++
drivers/acpi/sysfs.c | 31 +++++++++
include/acpi/acpi_bus.h | 1
5 files changed, 128 insertions(+)
Index: linux-pm/include/acpi/acpi_bus.h
===================================================================
--- linux-pm.orig/include/acpi/acpi_bus.h
+++ linux-pm/include/acpi/acpi_bus.h
@@ -286,6 +286,7 @@ struct acpi_device_physical_node {
u8 node_id;
struct list_head node;
struct device *dev;
+ bool put_online:1;
};
/* set maximum of physical nodes to 32 for expansibility */
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -27,6 +27,12 @@ extern struct acpi_device *acpi_root;
#define ACPI_IS_ROOT_DEVICE(device) (!(device)->parent)
+/*
+ * If set, devices will be hot-removed even if they cannot be put offline
+ * gracefully (from the kernel's standpoint).
+ */
+bool acpi_force_hot_remove;
+
static const char *dummy_hid = "device";
static LIST_HEAD(acpi_device_list);
@@ -120,6 +126,59 @@ acpi_device_modalias_show(struct device
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
+static acpi_status acpi_bus_offline_companions(acpi_handle handle, u32 lvl,
+ void *data, void **ret_p)
+{
+ struct acpi_device *device = NULL;
+ struct acpi_device_physical_node *pn;
+ acpi_status status = AE_OK;
+
+ if (acpi_bus_get_device(handle, &device))
+ return AE_OK;
+
+ mutex_lock(&device->physical_node_lock);
+
+ list_for_each_entry(pn, &device->physical_node_list, node) {
+ int ret;
+
+ ret = device_offline(pn->dev);
+ if (acpi_force_hot_remove)
+ continue;
+
+ if (ret < 0) {
+ status = AE_ERROR;
+ break;
+ }
+ pn->put_online = !ret;
+ }
+
+ mutex_unlock(&device->physical_node_lock);
+
+ return status;
+}
+
+static acpi_status acpi_bus_online_companions(acpi_handle handle, u32 lvl,
+ void *data, void **ret_p)
+{
+ struct acpi_device *device = NULL;
+ struct acpi_device_physical_node *pn;
+
+ if (acpi_bus_get_device(handle, &device))
+ return AE_OK;
+
+ mutex_lock(&device->physical_node_lock);
+
+ list_for_each_entry(pn, &device->physical_node_list, node)
+ if (pn->put_online) {
+ device_online(pn->dev);
+ pn->put_online = false;
+ }
+
+ mutex_unlock(&device->physical_node_lock);
+
+ return AE_OK;
+}
+
static int acpi_scan_hot_remove(struct acpi_device *device)
{
acpi_handle handle = device->handle;
@@ -136,10 +195,33 @@ static int acpi_scan_hot_remove(struct a
return -EINVAL;
}
+ lock_device_hotplug();
+
+ status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
+ NULL, acpi_bus_offline_companions, NULL,
+ NULL);
+ if (ACPI_SUCCESS(status) || acpi_force_hot_remove)
+ status = acpi_bus_offline_companions(handle, 0, NULL, NULL);
+
+ if (ACPI_FAILURE(status) && !acpi_force_hot_remove) {
+ acpi_bus_online_companions(handle, 0, NULL, NULL);
+ acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
+ acpi_bus_online_companions, NULL, NULL,
+ NULL);
+
+ unlock_device_hotplug();
+
+ put_device(&device->dev);
+ return -EBUSY;
+ }
+
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Hot-removing device %s...\n", dev_name(&device->dev)));
acpi_bus_trim(device);
+
+ unlock_device_hotplug();
+
/* Device node has been unregistered. */
put_device(&device->dev);
device = NULL;
@@ -236,6 +318,7 @@ static void acpi_scan_bus_device_check(a
int error;
mutex_lock(&acpi_scan_lock);
+ lock_device_hotplug();
acpi_bus_get_device(handle, &device);
if (device) {
@@ -259,6 +342,7 @@ static void acpi_scan_bus_device_check(a
kobject_uevent(&device->dev.kobj, KOBJ_ONLINE);
out:
+ unlock_device_hotplug();
acpi_evaluate_hotplug_ost(handle, ost_source, ost_code, NULL);
mutex_unlock(&acpi_scan_lock);
}
Index: linux-pm/drivers/acpi/sysfs.c
===================================================================
--- linux-pm.orig/drivers/acpi/sysfs.c
+++ linux-pm/drivers/acpi/sysfs.c
@@ -780,6 +780,33 @@ void acpi_sysfs_add_hotplug_profile(stru
pr_err(PREFIX "Unable to add hotplug profile '%s'\n", name);
}
+static ssize_t force_remove_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", !!acpi_force_hot_remove);
+}
+
+static ssize_t force_remove_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t size)
+{
+ bool val;
+ int ret;
+
+ ret = strtobool(buf, &val);
+ if (ret < 0)
+ return ret;
+
+ lock_device_hotplug();
+ acpi_force_hot_remove = val;
+ unlock_device_hotplug();
+ return size;
+}
+
+static const struct kobj_attribute force_remove_attr =
+ __ATTR(force_remove, S_IRUGO | S_IWUSR, force_remove_show,
+ force_remove_store);
+
int __init acpi_sysfs_init(void)
{
int result;
@@ -789,6 +816,10 @@ int __init acpi_sysfs_init(void)
return result;
hotplug_kobj = kobject_create_and_add("hotplug", acpi_kobj);
+ result = sysfs_create_file(hotplug_kobj, &force_remove_attr.attr);
+ if (result)
+ return result;
+
result = sysfs_create_file(acpi_kobj, &pm_profile_attr.attr);
return result;
}
Index: linux-pm/drivers/acpi/internal.h
===================================================================
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -47,6 +47,8 @@ void acpi_memory_hotplug_init(void);
static inline void acpi_memory_hotplug_init(void) {}
#endif
+extern bool acpi_force_hot_remove;
+
void acpi_sysfs_add_hotplug_profile(struct acpi_hotplug_profile *hotplug,
const char *name);
int acpi_scan_add_handler_with_hotplug(struct acpi_scan_handler *handler,
Index: linux-pm/Documentation/ABI/testing/sysfs-firmware-acpi
===================================================================
--- linux-pm.orig/Documentation/ABI/testing/sysfs-firmware-acpi
+++ linux-pm/Documentation/ABI/testing/sysfs-firmware-acpi
@@ -44,6 +44,16 @@ Description:
or 0 (unset). Attempts to write any other values to it will
cause -EINVAL to be returned.
+What: /sys/firmware/acpi/hotplug/force_remove
+Date: May 2013
+Contact: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
+Description:
+ The number in this file (0 or 1) determines whether (1) or not
+ (0) the ACPI subsystem will allow devices to be hot-removed even
+ if they cannot be put offline gracefully (from the kernel's
+ viewpoint). That number can be changed by writing a boolean
+ value to this file.
+
What: /sys/firmware/acpi/interrupts/
Date: February 2008
Contact: Len Brown <lenb@xxxxxxxxxx>
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