Rework acpi_bus_trim() and acpi_bus_device_attach(), which is
renamed as acpi_bus_attach(), to walk the list of each device
object's children directly and call themselves recursively for
each child instead of using acpi_walk_namespace().  This
simplifies the code quite a bit and avoids the overhead of
callbacks and the ACPICA's internal processing which are not
really necessary for these two routines.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Introduce a static inline function for setting the status field
of struct acpi_device on the basis of a supplied u32 number,
acpi_set_device_status(), and use it instead of the horrible
horrible STRUCT_TO_INT() macro wherever applicable.  Having done
that, drop STRUCT_TO_INT() (and pretend that it has never existed).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

The generic ACPI hotplug code used for several types of device
doesn't handle surprise removals, mostly because those devices
currently cannot be removed by surprise in the majority of systems.
However, surprise removals should be handled by that code as well
as surprise additions of devices, so make it do that.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

Move container-specific uevents from the core hotplug code to the
container scan handler's .attach() and .detach() callbacks.

This way the core will not have to special-case containers and
the uevents will be guaranteed to happen every time a container
is either scanned or trimmed as appropriate.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

Rework the common ACPI device hotplug code so that it is suitable
for PCI host bridge hotplug and switch the PCI host bridge scan
handler to using the common hotplug code.

This allows quite a few lines of code that are not necessary any more
to be dropped from the PCI host bridge scan handler and removes
arbitrary differences in behavior between PCI host bridge hotplug
and ACPI-based hotplug of other components, like CPUs and memory.

Also acpi_device_hotplug() can be static now.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

Modify the common ACPI device hotplug code to always queue up the
same function, acpi_device_hotplug(), using acpi_hotplug_execute()
and make the PCI host bridge hotplug code use that function too for
device hot removal.

This allows some code duplication to be reduced and a race condition
where the relevant ACPI handle may become invalid between the
notification handler and the function queued up by it via
acpi_hotplug_execute() to be avoided.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

If the scan handler for the given device has hotplug.enabled
unset, it doesn't really make sense to fail bus check and device
check notifications.

First, bus check may not have anything to do with the device it is
signaled for, but it may concern another device on the bus below
this one.  For this reason, bus check notifications should not be
failed if hotplug is disabled for the target device.

Second, device check notifications are signaled only after a device
has already appeared (or disappeared), so failing it can only prevent
scan handlers and drivers from attaching to that (already existing)
device, which is not very useful.

Consequently, if device hotplug is disabled through the device's
scan handler, fail eject request notifications only.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

Modify the ACPI namespace scanning code to register a struct
acpi_device object for every namespace node representing a device,
processor and so on, even if the device represented by that namespace
node is reported to be not present and not functional by _STA.

There are multiple reasons to do that.  First of all, it avoids
quite a lot of overhead when struct acpi_device objects are
deleted every time acpi_bus_trim() is run and then added again
by a subsequent acpi_bus_scan() for the same scope, although the
namespace objects they correspond to stay in memory all the time
(which always is the case on a vast majority of systems).

Second, it will allow user space to see that there are namespace
nodes representing devices that are not present at the moment and may
be added to the system.  It will also allow user space to evaluate
_SUN for those nodes to check what physical slots the "missing"
devices may be put into and it will make sense to add a sysfs
attribute for _STA evaluation after this change (that will be
useful for thermal management on some systems).

Next, it will help to consolidate the ACPI hotplug handling among
subsystems by making it possible to store hotplug-related information
in struct acpi_device objects in a standard common way.

Finally, it will help to avoid a race condition related to the
deletion of ACPI namespace nodes.  Namely, namespace nodes may be
deleted as a result of a table unload triggered by _EJ0 or _DCK.
If a hotplug notification for one of those nodes is triggered
right before the deletion and it executes a hotplug callback
via acpi_hotplug_execute(), the ACPI handle passed to that
callback may be stale when the callback actually runs.  One way
to work around that is to always pass struct acpi_device pointers
to hotplug callbacks after doing a get_device() on the objects in
question which eliminates the use-after-free possibility (the ACPI
handles in those objects are invalidated by acpi_scan_drop_device(),
so they will trigger ACPICA errors on attempts to use them).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

If an ACPI namespace node is removed (usually, as a result of a
table unload), and there is a data object attached to that node,
acpi_ns_delete_node() executes the removal handler submitted to
acpi_attach_data() for that object.  That handler is currently empty
for struct acpi_device objects, so it is necessary to detach those
objects from the corresponding ACPI namespace nodes in advance every
time a table unload may happen.  That is cumbersome and inefficient
and leads to some design constraints that turn out to be quite
inconvenient (in particular, struct acpi_device objects cannot be
registered for namespace nodes representing devices that are not
reported as present or functional by _STA).

For this reason, introduce a non-empty removal handler for ACPI
device objects that will unregister them when their ACPI namespace
nodes go away.

This code modification alone should not change functionality except
for the ordering of the ACPI hotplug workqueue which should not
matter (without subsequent code changes).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

The PCI host bridge scan handler installs its own notify handler,
handle_hotplug_event_root(), by itself.  Nevertheless, the ACPI
hotplug framework also installs the common notify handler,
acpi_hotplug_notify_cb(), for PCI root bridges.  This causes
acpi_hotplug_notify_cb() to call _OST method with unsupported
error as hotplug.enabled is not set.

To address this issue, introduce hotplug.ignore flag, which
indicates that the scan handler installs its own notify handler by
itself.  The ACPI hotplug framework does not install the common
notify handler when this flag is set.
Signed-off-by: NToshi Kani <toshi.kani@hp.com>
[rjw: Changed the name of the new flag]
Cc: 3.9+ <stable@vger.kernel.org> # 3.9+
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Before commit 6931007c (ACPI / scan: Start matching drivers
after trying scan handlers) the match_driver flag for all devices
was set in acpi_add_single_object(), but now it is set by
acpi_bus_device_attach() which is not called for the "fixed"
devices added by acpi_bus_scan_fixed().  This means that
flags.match_driver is never set for those devices now, so make
acpi_bus_scan_fixed() set it before calling device_attach().

Fixes: 6931007c (ACPI / scan: Start matching drivers after trying scan handlers)
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Since the PCI host bridge scan handler does not set hotplug.enabled,
the check of it in acpi_bus_device_eject() effectively prevents the
root bridge hot removal from working after commit a3b1b1ef
(ACPI / hotplug: Merge device hot-removal routines).  However, that
check is not necessary, because the other acpi_bus_device_eject()
users, acpi_hotplug_notify_cb and acpi_eject_store(), do the same
check by themselves before executing that function.

For this reason, remove the scan handler check from
acpi_bus_device_eject() to make PCI hot bridge hot removal work
again.

Fixes: a3b1b1ef (ACPI / hotplug: Merge device hot-removal routines)
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Since acpi_bus_get_device() returns a plain int and not acpi_status,
ACPI_FAILURE() should not be used for checking its return value.  Fix
that.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

There are two different interfaces for queuing up work items on the
ACPI hotplug workqueue, alloc_acpi_hp_work() used by PCI and PCI host
bridge hotplug code and acpi_os_hotplug_execute() used by the common
ACPI hotplug code and docking stations.  They both are somewhat
cumbersome to use and work slightly differently.

The users of alloc_acpi_hp_work() have to submit a work function that
will extract the necessary data items from a struct acpi_hp_work
object allocated by alloc_acpi_hp_work() and then will free that
object, while it would be more straightforward to simply use a work
function with one more argument and let the interface take care of
the execution details.

The users of acpi_os_hotplug_execute() also have to deal with the
fact that it takes only one argument in addition to the work function
pointer, although acpi_os_execute_deferred() actually takes care of
the allocation and freeing of memory, so it would have been able to
pass more arguments to the work function if it hadn't been
constrained by the connection with acpi_os_execute().

Moreover, while alloc_acpi_hp_work() makes GFP_KERNEL memory
allocations, which is correct, because hotplug work items are
always queued up from process context, acpi_os_hotplug_execute()
uses GFP_ATOMIC, as that is needed by acpi_os_execute().  Also,
acpi_os_execute_deferred() queued up by it waits for the ACPI event
workqueues to flush before executing the work function, whereas
alloc_acpi_hp_work() can't do anything similar.  That leads to
somewhat arbitrary differences in behavior between various ACPI
hotplug code paths and has to be straightened up.

For this reason, replace both alloc_acpi_hp_work() and
acpi_os_hotplug_execute() with a single interface,
acpi_hotplug_execute(), combining their behavior and being more
friendly to its users than any of the two.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>

According to the ACPI spec (5.0, Section 6.3.5), the "Device
insertion in progress (pending)" (0x80) _OST status code is
reserved for the "Insertion Processing" (0x200) source event
which is "a result of an OSPM action".  Specifically, it is not
a notification, so that status code should not be used during
notification processing, which unfortunately is done by
acpi_scan_bus_device_check().

For this reason, drop the ACPI_OST_SC_INSERT_IN_PROGRESS _OST
status evaluation from there (it was a mistake to put it in there
in the first place).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All applicable <stable@vger.kernel.org>

Since _handle_hotplug_event_root() is run from the ACPI hotplug
workqueue, it doesn't need to queue up a work item to eject a PCI
host bridge on the same workqueue.  Instead, it can just carry out
the eject by calling acpi_bus_device_eject() directly, so make that
happen.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There is no real reasn why acpi_bus_device_eject() and
acpi_bus_hot_remove_device() should work differently, so rework
acpi_bus_device_eject() so that it can be called internally by
both acpi_bus_hot_remove_device() and acpi_eject_store_work().
Accordingly, rework acpi_hotplug_notify_cb() to queue up the
execution of acpi_bus_hot_remove_device() through
acpi_os_hotplug_execute() on eject request notifications.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Notice that handle_root_bridge_removal() is the only user of
acpi_bus_hot_remove_device(), so it doesn't have to be exported
any more and can be made internal to the ACPI core.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Simplify handle_root_bridge_removal() and acpi_eject_store() by
getting rid of struct acpi_eject_event and passing device objects
directly to async routines executed via acpi_os_hotplug_execute().
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

In theory, an ACPI device object may be the parent of another
device object whose hotplug is disabled by user space through its
scan handler.  In that case, the eject operation targeting the
parent should fail as though the parent's own hotplug was disabled,
but currently this is not the case, because acpi_scan_hot_remove()
doesn't check the disable/enable hotplug status of the children
of the top-most object passed to it.

To fix this, modify acpi_bus_offline_companions() to return an
error code if hotplug is disabled for the given device object.
[Also change the name of the function to acpi_bus_offline(),
because it is not only about companions any more, and change
the name of acpi_bus_online_companions() accordingly.]  Make
acpi_scan_hot_remove() propagate that error to its callers.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

ACPI scan handlers should always be attached to struct acpi_device
objects before any ACPI drivers, but there is a window during which
a driver may be attached to a struct acpi_device before checking if
there is a matching scan handler.  Namely, that will happen if an
ACPI driver module is loaded during acpi_bus_scan() right after
the first namespace walk is complete and before the given device
is processed by the second namespace walk.

To prevent that from happening, set the match_driver flags of
struct acpi_device objects right before running device_attach()
for them in acpi_bus_device_attach().
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Two functions defined in device_pm.c, acpi_dev_pm_add_dependent()
and acpi_dev_pm_remove_dependent(), have no callers and may be
dropped, so drop them.

Moreover, they are the only functions adding entries to and removing
entries from the power_dependent list in struct acpi_device, so drop
that list too.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit caf5c03f (ACPI: Move acpi_bus_get_device() from bus.c to
scan.c) caused acpi_bus_get_device() to be exported using
EXPORT_SYMBOL_GPL(), but that broke some binary drivers in
existence, so revert that change.
Reported-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

"APIC" should be "ACPI" here.
Signed-off-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Change the ordering of device hotplug locks in scan.c so that
acpi_scan_lock is always acquired after device_hotplug_lock.

This will make it possible to use device_hotplug_lock around some
code paths that acquire acpi_scan_lock safely (most importantly
system suspend and hibernation).  Apart from that, acpi_scan_lock
is platform-specific and device_hotplug_lock is general, so the
new ordering appears to be more appropriate from the overall
design viewpoint.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

The current protocol for handling hot remove of containers is very
fragile and causes acpi_eject_store() to acquire acpi_scan_lock
which may deadlock with the removal of the device that it is called
for (the reason is that device sysfs attributes cannot be removed
while their callbacks are being executed and ACPI device objects
are removed under acpi_scan_lock).

The problem is related to the fact that containers are handled by
acpi_bus_device_eject() in a special way, which is to emit an
offline uevent instead of just removing the container.  Then, user
space is expected to handle that uevent and use the container's
"eject" attribute to actually remove it.  That is fragile, because
user space may fail to complete the ejection (for example, by not
using the container's "eject" attribute at all) leaving the BIOS
kind of in a limbo.  Moreover, if the eject event is not signaled
for a container itself, but for its parent device object (or
generally, for an ancestor above it in the ACPI namespace), the
container will be removed straight away without doing that whole
dance.

For this reason, modify acpi_bus_device_eject() to remove containers
synchronously like any other objects (user space will get its uevent
anyway in case it does some other things in response to it) and
remove the eject_pending ACPI device flag that is not used any more.
This way acpi_eject_store() doesn't have a reason to acquire
acpi_scan_lock any more and one possible deadlock scenario goes
away (plus the code is simplified a bit).
Reported-and-tested-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Move acpi_bus_get_device() from bus.c to scan.c which allows
acpi_bus_data_handler() to become static and clean up the latter.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There are several places in the tree where ACPI_STATE_D3 is used
instead of ACPI_STATE_D3_COLD which should be used instead for
clarity.  Modify them all to use ACPI_STATE_D3_COLD as appropriate.

[The definition of ACPI_STATE_D3 itself cannot go away at this point
 as it is part of ACPICA.]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NAaron Lu <aaron.lu@intel.com>

Functions acpi_dock_match() and acpi_bay_match() in scan.c can be
shared with dock.c to reduce code duplication, so export them as
global functions.

Also add a new function acpi_ata_match() to check whether an ACPI
device object represents an ATA device.

[rjw: Changelog]
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Introduce two helper functions, acpi_evaluate_ej0() and
acpi_evaluate_lck(), that will execute the _EJ0 and _LCK ACPI
control methods, respectively, and use them to simplify the
ACPI scan code.

[rjw: Changelog]
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Introduce helper function acpi_has_method() and use it in a number
of places to simplify code.

[rjw: Changelog]
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

An ACPI_NOTIFY_BUS_CHECK notification means that we should scan the
entire namespace starting from the given handle even if the device
represented by that handle is present (other devices below it may
just have appeared).

For this reason, modify acpi_scan_bus_device_check() to always run
acpi_bus_scan() if the notification being handled is of type
ACPI_NOTIFY_BUS_CHECK.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>
Cc: 3.10+ <stable@vger.kernel.org>

In acpi_bus_device_attach(), if there is an ACPI device object
for the given handle and that device object has a scan handler
attached to it already, there's nothing more to do for that handle.
Moreover, if acpi_scan_attach_handler() is called then, it may
execute the .attach() callback of the ACPI scan handler already
attached to the device object and that may lead to interesting
breakage.

For this reason, make acpi_bus_device_attach() return success
immediately when the handle's device object has a scan handler
attached to it.
Reported-by: NToshi Kani <toshi.kani@hp.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>
Cc: 3.10+ <stable@vger.kernel.org>

The acpi_device_list list is not used, so removed it.

[rjw: Changelog]
Signed-off-by: NHaicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

On HP Folio 13-2000, the BIOS defines a CMOS RTC Operation Region and
the EC's _REG methord accesses that region.  Thus an appropriate
address space handler must be registered for that region before the
EC driver is loaded.

Introduce a mechanism for adding CMOS RTC address space handlers.
Register an ACPI scan handler for CMOS RTC devices such that, when
a device of that kind is detected during an ACPI namespace scan, a
common CMOS RTC operation region address space handler will be
installed for it.

References: https://bugzilla.kernel.org/show_bug.cgi?id=54621Reported-and-tested-by: NStefan Nagy <public@stefan-nagy.at>
Signed-off-by: NLan Tianyu <tianyu.lan@intel.com>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit 3b63aaa7 (PCI: acpiphp: Do not use ACPI PCI subdriver
mechanism) introduced an ACPI dock support regression, because it
changed the relative initialization order of the ACPI dock subsystem
and the ACPI-based PCI hotplug (acpiphp).

Namely, the ACPI dock subsystem has to be initialized before
acpiphp_enumerate_slots() is first run, which after commit
3b63aaa7 happens during the initial enumeration of the PCI
hierarchy triggered by the initial ACPI namespace scan in
acpi_scan_init().  For this reason, the dock subsystem has to be
initialized before the initial ACPI namespace scan in
acpi_scan_init().

To make that happen, modify the ACPI dock subsystem to be
non-modular and add the invocation of its initialization routine,
acpi_dock_init(), to acpi_scan_init() directly before the initial
namespace scan.

[rjw: Changelog, removal of dock_exit().]
References: https://bugzilla.kernel.org/show_bug.cgi?id=59501Reported-and-tested-by: NAlexander E. Patrakov <patrakov@gmail.com>
Tested-by: NIllya Klymov <xanf@xanf.me>
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

ACPI drivers must not be bound to device objects having scan handlers
attatched to them, so make acpi_device_probe() fail with -EINVAL if the
device object being probed has an ACPI scan handler.

After this change the analogous check introduced into the ACPI video
driver by commit 8c9b7a7b (ACPI / video: Do not bind to device objects
with a scan handler) is not necessary any more and may be dropped, so
drop it.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NTony Luck <tony.luck@gmail.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>

There is no particular reason why acpi_bus_driver_init() needs to be
a separate function and its location with respect to its only caller,
acpi_device_probe(), makes the code a bit difficult to follow.

Besides, it doesn't really make sense to check if 'device' is not
NULL in acpi_bus_driver_init(), because we've already dereferenced
dev->driver in acpi_device_probe() at that point and, moreover,
'device' cannot be NULL then, because acpi_device_probe() is called
via really_probe() (which also sets dev->driver for that matter).

For these reasons, drop acpi_bus_driver_init() altogether and move
the remaining code from it directly into acpi_device_probe().
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

With the introduction of ACPI scan handlers, ACPI device objects
with an ACPI scan handler attached to them must not be bound to
by ACPI drivers any more.  Unfortunately, however, the ACPI video
driver attempts to do just that if there is a _ROM ACPI control
method defined under a device object with an ACPI scan handler.

Prevent that from happening by making the video driver's "add"
routine check if the device object already has an ACPI scan handler
attached to it and return an error code in that case.

That is not sufficient, though, because acpi_bus_driver_init() would
then clear the device object's driver_data that may be set by its
scan handler, so for the fix to work acpi_bus_driver_init() has to be
modified to leave driver_data as is on errors.

References: https://bugzilla.kernel.org/show_bug.cgi?id=58091Bisected-and-tested-by: NDmitry S. Demin <dmitryy.demin@gmail.com>
Reported-and-tested-by: NJason Cassell <bluesloth600@gmail.com>
Tracked-down-by: NAaron Lu <aaron.lu@intel.com>
Cc: 3.9+ <stable@kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NAaron Lu <aaron.lu@intel.com>

Commit 9f29ab11 ("ACPI / scan: do not match drivers against objects
having scan handlers") introduced a boot regression on Tony's ia64 HP
rx2600.  Tony says:

  "It panics with the message:

   Kernel panic - not syncing: Unable to find SBA IOMMU: Try a generic or DIG kernel

   [...] my problem comes from arch/ia64/hp/common/sba_iommu.c
   where the code in sba_init() says:

        acpi_bus_register_driver(&acpi_sba_ioc_driver);
        if (!ioc_list) {

   but because of this change we never managed to call ioc_init()
   so ioc_list doesn't get set up, and we die."

Revert it to avoid this breakage and we'll fix the problem it attempted
to address later.
Reported-by: NTony Luck <tony.luck@gmail.com>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>