Re: [PATCH 2/2] ACPI / hotplug / driver core: Handle containers in a special way
On Fri, Dec 27, 2013 at 11:28:34PM +0100, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > 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 > device 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. > > Signed-off-by: Rafael J. Wysocki > Tested-by: Yasuaki Ishimatsu Acked-by: Greg Kroah-Hartman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 2/2] ACPI / hotplug / driver core: Handle containers in a special way
From: Rafael J. Wysocki
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
device 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.
Signed-off-by: Rafael J. Wysocki
Tested-by: Yasuaki Ishimatsu
---
drivers/acpi/container.c | 48 ++
drivers/acpi/internal.h |1
drivers/acpi/scan.c |8 ---
drivers/base/Makefile |2 -
drivers/base/base.h |1
drivers/base/container.c | 44 ++
drivers/base/init.c |1
include/linux/container.h | 25 +++
8 files changed, 122 insertions(+), 8 deletions(-)
Index: linux-pm/include/linux/container.h
===
--- /dev/null
+++ linux-pm/include/linux/container.h
@@ -0,0 +1,25 @@
+/*
+ * Definitions for container bus type.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Rafael J. Wysocki
+ *
+ * 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
+
+/* drivers/base/power/container.c */
+extern struct bus_type container_subsys;
+
+struct container_dev {
+ struct device dev;
+ int (*offline)(struct container_dev *cdev);
+};
+
+static inline struct container_dev *to_container_dev(struct device *dev)
+{
+ return container_of(dev, struct container_dev, dev);
+}
Index: linux-pm/drivers/base/container.c
===
--- /dev/null
+++ linux-pm/drivers/base/container.c
@@ -0,0 +1,44 @@
+/*
+ * System bus type for containers.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Rafael J. Wysocki
+ *
+ * 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
+
+#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 = CO
[Update][PATCH 2/2] ACPI / hotplug / driver core: Handle containers in a special way
From: Rafael J. Wysocki
Subject: 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.
Signed-off-by: Rafael J. Wysocki
---
Hi,
I've realized that I don't need to abuse driver_data here if I define a
struct container_dev based on struct device and containing a pointer to the
offline routine, so here goes an update with that modification.
I checked that my venerable Toshiba test box boots the kernel with [1/2] and
this patch applied and that the container bus type is present then as expected,
so it is not totally untested any more. I still need to test the creation of
container devices, though.
Thanks,
Rafael
---
drivers/acpi/container.c | 42 ++
drivers/acpi/internal.h |1 +
drivers/acpi/scan.c |8 +---
drivers/base/Makefile |2 +-
drivers/base/base.h |1 +
drivers/base/container.c | 44
drivers/base/init.c |1 +
include/linux/container.h | 25 +
8 files changed, 116 insertions(+), 8 deletions(-)
Index: linux-pm/include/linux/container.h
===
--- /dev/null
+++ linux-pm/include/linux/container.h
@@ -0,0 +1,25 @@
+/*
+ * Definitions for container bus type.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Rafael J. Wysocki
+ *
+ * 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
+
+/* drivers/base/power/container.c */
+extern struct bus_type container_subsys;
+
+struct container_dev {
+ struct device dev;
+ int (*offline)(struct container_dev *cdev);
+};
+
+static inline struct container_dev *to_container_dev(struct device *dev)
+{
+ return container_of(dev, struct container_dev, dev);
+}
Index: linux-pm/drivers/base/container.c
===
--- /dev/null
+++ linux-pm/drivers/base/container.c
@@ -0,0 +1,44 @@
+/*
+ * System bus type for containers.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Rafael J. Wysocki
+ *
+ * This program is free softw
