ACPI / hotplug / PCI: Remove entries from bus->devices in reverse order

According to the changelog of commit 29ed1f29b68a (PCI: pciehp: Fix null
pointer deref when hot-removing SR-IOV device) it is unsafe to walk the
bus->devices list of a PCI bus and remove devices from it in direct order,
because that may lead to NULL pointer dereferences related to virtual
functions.

For this reason, change all of the bus->devices list walks in
acpiphp_glue.c during which devices may be removed to be carried out in
reverse order.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
ACPI / hotplug / PCI: Move PCI rescan-remove locking to hotplug_event()

Commit 9217a984671e (ACPI / hotplug / PCI: Use global PCI rescan-remove
locking) modified ACPIPHP to protect its PCI device removal and addition
code paths from races against sysfs-driven rescan and remove operations
with the help of PCI rescan-remove locking.  However, it overlooked the
fact that hotplug_event_work() is not the only caller of hotplug_event()
which may also be called by dock_hotplug_event() and that code path
is missing the PCI rescan-remove locking.  This means that, although
the PCI rescan-remove lock is held as appropriate during the handling
of events originating from handle_hotplug_event(), the ACPIPHP's
operations resulting from dock events may still suffer the race
conditions that commit 9217a984671e was supposed to eliminate.

To address that problem, move the PCI rescan-remove locking from
hotplug_event_work() to hotplug_event() so that it is used regardless
of the way that function is invoked.

Revamps: 9217a984671e (ACPI / hotplug / PCI: Use global PCI rescan-remove locking)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
ACPI / hotplug / PCI: Scan root bus under the PCI rescan-remove lock

Since acpiphp_check_bridge() called by acpiphp_check_host_bridge()
does things that require PCI rescan-remove locking around it,
make acpiphp_check_host_bridge() use that locking.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
ACPI / hotplug / PCI: Fix bridge removal race in handle_hotplug_event()

If a PCI bridge with an ACPIPHP context attached is removed via
sysfs, the code path executed as a result is the following:

pci_stop_and_remove_bus_device_locked
 pci_remove_bus
  pcibios_remove_bus
   acpi_pci_remove_bus
    acpiphp_remove_slots
     cleanup_bridge
     put_bridge
      free_bridge
       acpiphp_put_context (for each child, under context lock)
        kfree (child context)

Now, if a hotplug notify is dispatched for one of the bridge's
children and the timing is such that handle_hotplug_event() for
that notify is executed while free_bridge() above is running,
the get_bridge(context->func.parent) in handle_hotplug_event()
will not really help, because it is too late to prevent the bridge
from going away and the child's context may be freed before
hotplug_event_work() scheduled from handle_hotplug_event()
dereferences the pointer to it passed via the data argument.
That will cause a kernel crash to happpen in hotplug_event_work().

To prevent that from happening, make handle_hotplug_event()
check the is_going_away flag of the function's parent bridge
(under acpiphp_context_lock) and bail out if it's set.  Also,
make cleanup_bridge() set the bridge's is_going_away flag under
acpiphp_context_lock so that it cannot be changed between the
check and the subsequent get_bridge(context->func.parent) in
handle_hotplug_event().

Then, in the above scenario, handle_hotplug_event() will notice
that context->func.parent->is_going_away is already set and it
will exit immediately preventing the crash from happening.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / hotplug / PCI: Fix bridge removal race vs dock events

If a PCI bridge with an ACPIPHP context attached is removed via
sysfs, the code path executed as a result is the following:

pci_stop_and_remove_bus_device_locked
 pci_remove_bus
  pcibios_remove_bus
   acpi_pci_remove_bus
    acpiphp_remove_slots
     cleanup_bridge
      unregister_hotplug_dock_device (drops dock references to the bridge)
     put_bridge
      free_bridge
       acpiphp_put_context (for each child, under context lock)
        kfree (context)

Now, if a dock event affecting one of the bridge's child devices
occurs (roughly at the same time), it will lead to the following code
path:

acpi_dock_deferred_cb
 dock_notify
  handle_eject_request
   hot_remove_dock_devices
    dock_hotplug_event
     hotplug_event (dereferences context)

That may lead to a kernel crash in hotplug_event() if it is executed
after the last kfree() in the bridge removal code path.

To prevent that from happening, add a wrapper around hotplug_event()
called dock_event() and point the .handler pointer in acpiphp_dock_ops
to it.  Make that wrapper retrieve the device's ACPIPHP context using
acpiphp_get_context() (instead of taking it from the data argument)
under acpiphp_context_lock and check if the parent bridge's
is_going_away flag is set.  If that flag is set, it will return
immediately and if it is not set it will grab a reference to the
device's parent bridge before executing hotplug_event().

Then, in the above scenario, the reference to the parent bridge
held by dock_event() will prevent free_bridge() from being executed
for it until hotplug_event() returns.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
intel_pstate: Take core C0 time into account for core busy calculation

Take non-idle time into account when calculating core busy time.
This ensures that intel_pstate will notice a decrease in load.

References: https://bugzilla.kernel.org/show_bug.cgi?id=66581
Cc: 3.10+ <stable@vger.kernel.org> # 3.10+
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / video: Add HP EliteBook Revolve 810 to the blacklist

On HP EliteBook Revolve 810 the ACPI backlight device doesn't work as
expected. For example when resuming from system sleep, it seems to lose
backlight settings.

Forcing Intel driver fixes the problem so add this machine the ACPI
video detect blacklist.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / utils: remove a pointless NULL check

"element" can't be NULL because it is the address of a struct member.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / proc: remove unneeded NULL check

We already verified that "ldev" was non-NULL earlier and also we
dereference again without checking a three lines later.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / battery: Fix incorrect sscanf() string in acpi_battery_init_alarm()

Fix incorrect sscanf() string in acpi_battery_init_alarm().
Change from %ld to %lu, because 'x' is unsigned long.

Signed-off-by: Luis G.F <luisgf@luisgf.es>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / hotplug: Fix panic on eject to ejected device

When an eject request is sent to an ejected ACPI device, the following
panic occurs:

 ACPI: \_SB_.SCK3.CPU3: ACPI_NOTIFY_EJECT_REQUEST event
 BUG: unable to handle kernel NULL pointer dereference at 0000000000000070
 IP: [<ffffffff813a7cfe>] acpi_device_hotplug+0x10b/0x33b
	:
 Call Trace:
 [<ffffffff813a24da>] acpi_hotplug_work_fn+0x1c/0x27
 [<ffffffff8109cbe5>] process_one_work+0x175/0x430
 [<ffffffff8109d7db>] worker_thread+0x11b/0x3a0

This is becase device->handler is NULL in acpi_device_hotplug().
This case was used to fail in acpi_hotplug_notify_cb() as the target
had no acpi_deivce.  However, acpi_device now exists after ejection.

Added a check to verify if acpi_device->handler is valid for an
eject request in acpi_hotplug_notify_cb().  Note that handler passed
from an argument is still valid while acpi_device->handler is NULL.

Fixes: 202317a573b2 (ACPI / scan: Add acpi_device objects for all device nodes in the namespace)
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branches 'acpi-pci-hotplug' and 'acpi-hotplug'

* acpi-pci-hotplug:
  ACPI / hotplug / PCI: Fix bridge removal race vs dock events
  ACPI / hotplug / PCI: Fix bridge removal race in handle_hotplug_event()
  ACPI / hotplug / PCI: Scan root bus under the PCI rescan-remove lock
  ACPI / hotplug / PCI: Move PCI rescan-remove locking to hotplug_event()
  ACPI / hotplug / PCI: Remove entries from bus->devices in reverse order

* acpi-hotplug:
  ACPI / hotplug: Fix panic on eject to ejected device
Merge branch 'pm-cpufreq'

* pm-cpufreq:
  intel_pstate: Take core C0 time into account for core busy calculation
Merge branches 'acpi-cleanup' and 'acpi-video'

* acpi-cleanup:
  ACPI / battery: Fix incorrect sscanf() string in acpi_battery_init_alarm()
  ACPI / proc: remove unneeded NULL check
  ACPI / utils: remove a pointless NULL check

* acpi-video:
  ACPI / video: Add HP EliteBook Revolve 810 to the blacklist