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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-12-29 15:25:48 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-12-29 15:25:48 +0100
commitcaa73ea158de9419f08e456f2716c71d1f06012a (patch)
treeca948019c9a0c142880fbfadf028d9114fafe529 /drivers/base
parentd22ddcbc4fb7a483d0721eddfda3f0558821d372 (diff)
downloadlinux-caa73ea158de9419f08e456f2716c71d1f06012a.tar.bz2
ACPI / hotplug / driver core: Handle containers in a special way
ACPI container devices require special hotplug handling, at least on some systems, since generally user space needs to carry out system-specific cleanup before it makes sense to offline devices in the container. However, the current ACPI hotplug code for containers first attempts to offline devices in the container and only then it notifies user space of the container offline. Moreover, after commit 202317a573b2 (ACPI / scan: Add acpi_device objects for all device nodes in the namespace), ACPI device objects representing containers are present as long as the ACPI namespace nodes corresponding to them are present, which may be forever, even if the container devices are physically detached from the system (the return values of the corresponding _STA methods change in those cases, but generally the namespace nodes themselves are still there). Thus it is useful to introduce entities representing containers that will go away during container hot-unplug. The goal of this change is to address both the above issues. The idea is to create a "companion" container system device for each of the ACPI container device objects during the initial namespace scan or on a hotplug event making the container present. That system device will be unregistered on container removal. A new bus type for container devices is added for this purpose, because device offline and online operations need to be defined for them. The online operation is a trivial function that is always successful and the offline uses a callback pointed to by the container device's offline member. For ACPI containers that callback simply walks the list of ACPI device objects right below the container object (its children) and checks if all of their physical companion devices are offline. If that's not the case, it returns -EBUSY and the container system devivce cannot be put offline. Consequently, to put the container system device offline, it is necessary to put all of the physical devices depending on its ACPI companion object offline beforehand. Container system devices created for ACPI container objects are initially online. They are created by the container ACPI scan handler whose hotplug.demand_offline flag is set. That causes acpi_scan_hot_remove() to check if the companion container system device is offline before attempting to remove an ACPI container or any devices below it. If the check fails, a KOBJ_CHANGE uevent is emitted for the container system device in question and user space is expected to offline all devices below the container and the container itself in response to it. Then, user space can finalize the removal of the container with the help of its ACPI device object's eject attribute in sysfs. Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/Makefile2
-rw-r--r--drivers/base/base.h1
-rw-r--r--drivers/base/container.c44
-rw-r--r--drivers/base/init.c1
4 files changed, 47 insertions, 1 deletions
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 94e8a80e87f8..d08c9d3b1d37 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -4,7 +4,7 @@ obj-y := core.o bus.o dd.o syscore.o \
driver.o class.o platform.o \
cpu.o firmware.o init.o map.o devres.o \
attribute_container.o transport_class.o \
- topology.o
+ topology.o container.o
obj-$(CONFIG_DEVTMPFS) += devtmpfs.o
obj-$(CONFIG_DMA_CMA) += dma-contiguous.o
obj-y += power/
diff --git a/drivers/base/base.h b/drivers/base/base.h
index 2cbc6774f4cd..24f424249d9b 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -100,6 +100,7 @@ static inline int hypervisor_init(void) { return 0; }
#endif
extern int platform_bus_init(void);
extern void cpu_dev_init(void);
+extern void container_dev_init(void);
struct kobject *virtual_device_parent(struct device *dev);
diff --git a/drivers/base/container.c b/drivers/base/container.c
new file mode 100644
index 000000000000..ecbfbe2e908f
--- /dev/null
+++ b/drivers/base/container.c
@@ -0,0 +1,44 @@
+/*
+ * System bus type for containers.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/container.h>
+
+#include "base.h"
+
+#define CONTAINER_BUS_NAME "container"
+
+static int trivial_online(struct device *dev)
+{
+ return 0;
+}
+
+static int container_offline(struct device *dev)
+{
+ struct container_dev *cdev = to_container_dev(dev);
+
+ return cdev->offline ? cdev->offline(cdev) : 0;
+}
+
+struct bus_type container_subsys = {
+ .name = CONTAINER_BUS_NAME,
+ .dev_name = CONTAINER_BUS_NAME,
+ .online = trivial_online,
+ .offline = container_offline,
+};
+
+void __init container_dev_init(void)
+{
+ int ret;
+
+ ret = subsys_system_register(&container_subsys, NULL);
+ if (ret)
+ pr_err("%s() failed: %d\n", __func__, ret);
+}
diff --git a/drivers/base/init.c b/drivers/base/init.c
index c16f0b808a17..da033d3bab3c 100644
--- a/drivers/base/init.c
+++ b/drivers/base/init.c
@@ -33,4 +33,5 @@ void __init driver_init(void)
platform_bus_init();
cpu_dev_init();
memory_dev_init();
+ container_dev_init();
}