linux-stable.git/drivers/acpi/scan.c, branch linux-3.16.y Linux kernel stable tree ACPI / scan: Annotate physical_node_lock in acpi_scan_is_offline() 2015-05-06T09:36:22+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2015-04-17T23:25:46+00:00 07e6af17f9b4da01ff9f285473b9b33f0b67790b commit 4c533c801d1c9b5c38458a0e7516e0cf50643782 upstream. acpi_scan_is_offline() may be called under the physical_node_lock lock of the given device object's parent, so prevent lockdep from complaining about that by annotating that instance with SINGLE_DEPTH_NESTING. Fixes: caa73ea158de (ACPI / hotplug / driver core: Handle containers in a special way) Reported-and-tested-by: Xie XiuQi <xiexiuqi@huawei.com> Reviewed-by: Toshi Kani <toshi.kani@hp.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit 4c533c801d1c9b5c38458a0e7516e0cf50643782 upstream.

acpi_scan_is_offline() may be called under the physical_node_lock
lock of the given device object's parent, so prevent lockdep from
complaining about that by annotating that instance with
SINGLE_DEPTH_NESTING.

Fixes: caa73ea158de (ACPI / hotplug / driver core: Handle containers in a special way)
Reported-and-tested-by: Xie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
ACPI / scan: No implicit wake notification for buttons 2015-01-16T14:34:52+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2014-07-14T20:41:41+00:00 79d914f5fe330ffbeb578c03560bb7a80252832d commit bd9b2f9aff26c185c1f8e0cd08a850ee4ace391a upstream. The ACPI device enumeration code in Linux assumes that buttons always are wakeup devices, so it calls acpi_setup_gpe_for_wake() for them which leads to undesirable side effects. Namely, that function sets up implicit device wake notification mechanism for a given GPE if there is no handler method in the ACPI namespace, which from the ACPICA's perspective means that there always is a way to handle that GPE if enabled. However, we don't handle wake notify events for buttons, so if there are no handler methods for their GPEs in the namespace, enabling a button GPE at run time leads to a GPE storm in some cases (the GPE triggers, ACPICA carries out the implicit wake notification for it which isn't handled, so the GPE triggers again and so on). To prevent that from happening use acpi_mark_gpe_for_wake() instead of acpi_setup_gpe_for_wake() for buttons which will cause ACPICA to only enable button GPEs if there are handler methods for the in the namespace. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Joseph Salisbury <joseph.salisbury@canonical.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit bd9b2f9aff26c185c1f8e0cd08a850ee4ace391a upstream.

The ACPI device enumeration code in Linux assumes that buttons always
are wakeup devices, so it calls acpi_setup_gpe_for_wake() for them
which leads to undesirable side effects.  Namely, that function sets
up implicit device wake notification mechanism for a given GPE if
there is no handler method in the ACPI namespace, which from the
ACPICA's perspective means that there always is a way to handle
that GPE if enabled.  However, we don't handle wake notify events
for buttons, so if there are no handler methods for their GPEs in
the namespace, enabling a button GPE at run time leads to a GPE
storm in some cases (the GPE triggers, ACPICA carries out the
implicit wake notification for it which isn't handled, so the
GPE triggers again and so on).

To prevent that from happening use acpi_mark_gpe_for_wake()
instead of acpi_setup_gpe_for_wake() for buttons which will cause
ACPICA to only enable button GPEs if there are handler methods for
the in the namespace.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Joseph Salisbury <joseph.salisbury@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
ACPI / PM: Fix PM initialization for devices that are not present 2015-01-16T14:34:26+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2015-01-01T22:38:28+00:00 22c26de878018d2a8fe6abab65c5fd7ce840e706 commit 1b1f3e1699a9886f1070f94171097ab4ccdbfc95 upstream. If an ACPI device object whose _STA returns 0 (not present and not functional) has _PR0 or _PS0, its power_manageable flag will be set and acpi_bus_init_power() will return 0 for it. Consequently, if such a device object is passed to the ACPI device PM functions, they will attempt to carry out the requested operation on the device, although they should not do that for devices that are not present. To fix that problem make acpi_bus_init_power() return an error code for devices that are not present which will cause power_manageable to be cleared for them as appropriate in acpi_bus_get_power_flags(). However, the lists of power resources should not be freed for the device in that case, so modify acpi_bus_get_power_flags() to keep those lists even if acpi_bus_init_power() returns an error. Accordingly, when deciding whether or not the lists of power resources need to be freed, acpi_free_power_resources_lists() should check the power.flags.power_resources flag instead of flags.power_manageable, so make that change too. Furthermore, if acpi_bus_attach() sees that flags.initialized is unset for the given device, it should reset the power management settings of the device and re-initialize them from scratch instead of relying on the previous settings (the device may have appeared after being not present previously, for example), so make it use the 'valid' flag of the D0 power state as the initial value of flags.power_manageable for it and call acpi_bus_init_power() to discover its current power state. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit 1b1f3e1699a9886f1070f94171097ab4ccdbfc95 upstream.

If an ACPI device object whose _STA returns 0 (not present and not
functional) has _PR0 or _PS0, its power_manageable flag will be set
and acpi_bus_init_power() will return 0 for it.  Consequently, if
such a device object is passed to the ACPI device PM functions, they
will attempt to carry out the requested operation on the device,
although they should not do that for devices that are not present.

To fix that problem make acpi_bus_init_power() return an error code
for devices that are not present which will cause power_manageable to
be cleared for them as appropriate in acpi_bus_get_power_flags().
However, the lists of power resources should not be freed for the
device in that case, so modify acpi_bus_get_power_flags() to keep
those lists even if acpi_bus_init_power() returns an error.
Accordingly, when deciding whether or not the lists of power
resources need to be freed, acpi_free_power_resources_lists()
should check the power.flags.power_resources flag instead of
flags.power_manageable, so make that change too.

Furthermore, if acpi_bus_attach() sees that flags.initialized is
unset for the given device, it should reset the power management
settings of the device and re-initialize them from scratch instead
of relying on the previous settings (the device may have appeared
after being not present previously, for example), so make it use
the 'valid' flag of the D0 power state as the initial value of
flags.power_manageable for it and call acpi_bus_init_power() to
discover its current power state.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
ACPI / scan: Correct error return value of create_modalias() 2014-10-05T20:41:02+00:00 Mika Westerberg mika.westerberg@linux.intel.com 2014-09-12T08:33:10+00:00 71f2d795ab0fad48751728c347562486af566c1f commit 98d28d0e59160d2d6cb3f6a9050723ac40f89669 upstream. There is a typo, it should be negative -errno instead. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 98d28d0e59160d2d6cb3f6a9050723ac40f89669 upstream.

There is a typo, it should be negative -errno instead.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ACPI / hotplug: Generate online uevents for ACPI containers 2014-10-05T20:41:02+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2014-09-21T00:58:18+00:00 fffa93ce4430c0615041067d3db71f61baab0bd8 commit 8ab17fc92e49bc2b8fff9d220c19bf50ec9c1158 upstream. Commit 46394fd01 (ACPI / hotplug: Move container-specific code out of the core) removed the generation of "online" uevents for containers, because "add" uevents are now generated for them automatically when container system devices are registered. However, there are user space tools that need to be notified when the container and all of its children have been enumerated, which doesn't happen any more. For this reason, add a mechanism allowing "online" uevents to be generated for ACPI containers after enumerating the container along with all of its children. Fixes: 46394fd01 (ACPI / hotplug: Move container-specific code out of the core) Reported-and-tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8ab17fc92e49bc2b8fff9d220c19bf50ec9c1158 upstream.

Commit 46394fd01 (ACPI / hotplug: Move container-specific code out of
the core) removed the generation of "online" uevents for containers,
because "add" uevents are now generated for them automatically when
container system devices are registered.  However, there are user
space tools that need to be notified when the container and all of
its children have been enumerated, which doesn't happen any more.

For this reason, add a mechanism allowing "online" uevents to be
generated for ACPI containers after enumerating the container along
with all of its children.

Fixes: 46394fd01 (ACPI / hotplug: Move container-specific code out of the core)
Reported-and-tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ACPI / scan: not cache _SUN value in struct acpi_device_pnp 2014-09-17T16:22:10+00:00 Yasuaki Ishimatsu isimatu.yasuaki@jp.fujitsu.com 2014-09-03T04:39:13+00:00 ca16ec3a32087b907e18db2a4af20f4d1bd9d0ed commit a383b68d9fe9864c4d3b86f67ad6488f58136435 upstream. The _SUN device indentification object is not guaranteed to return the same value every time it is executed, so we should not cache its return value, but rather execute it every time as needed. If it is cached, an incorrect stale value may be used in some situations. This issue was exposed by commit 202317a573b2 (ACPI / scan: Add acpi_device objects for all device nodes in the namespace). Fix it by avoiding to cache the return value of _SUN. Fixes: 202317a573b2 (ACPI / scan: Add acpi_device objects for all device nodes in the namespace) Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a383b68d9fe9864c4d3b86f67ad6488f58136435 upstream.

The _SUN device indentification object is not guaranteed to return
the same value every time it is executed, so we should not cache its
return value, but rather execute it every time as needed.  If it is
cached, an incorrect stale value may be used in some situations.

This issue was exposed by commit 202317a573b2 (ACPI / scan: Add
acpi_device objects for all device nodes in the namespace).  Fix it
by avoiding to cache the return value of _SUN.

Fixes: 202317a573b2 (ACPI / scan: Add acpi_device objects for all device nodes in the namespace)
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ACPI / scan: Allow ACPI drivers to bind to PNP device objects 2014-09-17T16:22:09+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2014-08-25T23:29:21+00:00 afdd3bcc760e02740b2a375a0ad6447e3da3959f commit fc2e0a8326d1b21d11ef8213298e5302867fed2c upstream. We generally don't allow ACPI drivers to bind to ACPI device objects that companion "physical" device objects are created for to avoid situations in which two different drivers may attempt to handle one device at the same time. Recent ACPI device enumeration rework extended that approach to ACPI PNP devices by starting to use a scan handler for enumerating them. However, we previously allowed ACPI drivers to bind to ACPI device objects with existing PNP device companions and changing that led to functional regressions on some systems. For this reason, add a special check for PNP devices in acpi_device_probe() so that ACPI drivers can bind to ACPI device objects having existing PNP device companions as before. Fixes: eec15edbb0e1 (ACPI / PNP: use device ID list for PNPACPI device enumeration) Link: https://bugzilla.kernel.org/show_bug.cgi?id=81511 Link: https://bugzilla.kernel.org/show_bug.cgi?id=81971 Reported-by: Gabriele Mazzotta <gabriele.mzt@gmail.com> Reported-by: Dirk Griesbach <spamthis@freenet.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit fc2e0a8326d1b21d11ef8213298e5302867fed2c upstream.

We generally don't allow ACPI drivers to bind to ACPI device objects
that companion "physical" device objects are created for to avoid
situations in which two different drivers may attempt to handle one
device at the same time.  Recent ACPI device enumeration rework
extended that approach to ACPI PNP devices by starting to use a scan
handler for enumerating them.  However, we previously allowed ACPI
drivers to bind to ACPI device objects with existing PNP device
companions and changing that led to functional regressions on some
systems.

For this reason, add a special check for PNP devices in
acpi_device_probe() so that ACPI drivers can bind to ACPI device
objects having existing PNP device companions as before.

Fixes: eec15edbb0e1 (ACPI / PNP: use device ID list for PNPACPI device enumeration)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=81511
Link: https://bugzilla.kernel.org/show_bug.cgi?id=81971
Reported-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Reported-by: Dirk Griesbach <spamthis@freenet.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ACPI: Run fixed event device notifications in process context 2014-09-17T16:22:09+00:00 Lan Tianyu tianyu.lan@intel.com 2014-08-25T23:29:24+00:00 baf705af97bd84b867de7e16016b3be8cfd99b9a commit 236105db632c6279a020f78c83e22eaef746006b upstream. Currently, notify callbacks for fixed button events are run from interrupt context. That is not necessary and after commit 0bf6368ee8f2 (ACPI / button: Add ACPI Button event via netlink routine) it causes netlink routines to be called from interrupt context which is not correct. Also, that is different from non-fixed device events (including non-fixed button events) whose notify callbacks are all executed from process context. For the above reasons, make fixed button device notify callbacks run in process context which will avoid the deadlock when using netlink to report button events to user space. Fixes: 0bf6368ee8f2 (ACPI / button: Add ACPI Button event via netlink routine) Link: https://lkml.org/lkml/2014/8/21/606 Reported-by: Benjamin Block <bebl@mageta.org> Reported-by: Knut Petersen <Knut_Petersen@t-online.de> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> [rjw: Function names, subject and changelog.] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 236105db632c6279a020f78c83e22eaef746006b upstream.

Currently, notify callbacks for fixed button events are run from
interrupt context.  That is not necessary and after commit 0bf6368ee8f2
(ACPI / button: Add ACPI Button event via netlink routine) it causes
netlink routines to be called from interrupt context which is not
correct.

Also, that is different from non-fixed device events (including
non-fixed button events) whose notify callbacks are all executed from
process context.

For the above reasons, make fixed button device notify callbacks run
in process context which will avoid the deadlock when using netlink
to report button events to user space.

Fixes: 0bf6368ee8f2 (ACPI / button: Add ACPI Button event via netlink routine)
Link: https://lkml.org/lkml/2014/8/21/606
Reported-by: Benjamin Block <bebl@mageta.org>
Reported-by: Knut Petersen <Knut_Petersen@t-online.de>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
[rjw: Function names, subject and changelog.]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ACPI / hotplug: Check scan handlers in acpi_scan_hot_remove() 2014-09-17T16:22:09+00:00 Tang Chen tangchen@cn.fujitsu.com 2014-08-08T02:30:45+00:00 02e9190b3bb4acc95b527539f6ec0f7a0982d6aa commit dee1592638ab7ea35a32179b73f9284dead49c03 upstream. When ACPI_HOTPLUG_MEMORY is not configured, memory_device_handler.attach is not set. In acpi_scan_attach_handler(), the acpi_device->handler will not be initialized. In acpi_scan_hot_remove(), it doesn't check if acpi_device->handler is NULL. If we do memory hot-remove without ACPI_HOTPLUG_MEMORY configured, the kernel will panic. BUG: unable to handle kernel NULL pointer dereference at 0000000000000088 IP: [<ffffffff813e318f>] acpi_device_hotplug+0x1d7/0x4c4 PGD 0 Oops: 0000 [#1] SMP Modules linked in: sd_mod(E) sr_mod(E) cdrom(E) crc_t10dif(E) crct10dif_common(E) ata_piix(E) libata(E) CPU: 0 PID: 41 Comm: kworker/u2:1 Tainted: G E 3.16.0-rc7--3.16-rc7-tangchen+ #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 Workqueue: kacpi_hotplug acpi_hotplug_work_fn task: ffff8800182436c0 ti: ffff880018254000 task.ti: ffff880018254000 RIP: 0010:[<ffffffff813e318f>] [<ffffffff813e318f>] acpi_device_hotplug+0x1d7/0x4c4 RSP: 0000:ffff880018257da8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88001cd8d800 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff88001e40e6f8 RDI: 0000000000000246 RBP: ffff880018257df0 R08: 0000000000000096 R09: 00000000000011a0 R10: 63735f6970636120 R11: 725f746f685f6e61 R12: 0000000000000003 R13: ffff88001cc1c400 R14: ffff88001e062028 R15: 0000000000000040 FS: 0000000000000000(0000) GS:ffff88001e400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000088 CR3: 000000001a9a2000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 0000000000000000 DR7: 0000000000000000 Stack: 00000000523cab58 ffff88001cd8d9f8 ffff88001852d480 00000000523cab58 ffff88001852d480 ffff880018221e40 ffff88001cc1c400 ffff88001cce2d00 0000000000000040 ffff880018257e08 ffffffff813dc31d ffff88001852d480 Call Trace: [<ffffffff813dc31d>] acpi_hotplug_work_fn+0x1e/0x29 [<ffffffff8108eefb>] process_one_work+0x17b/0x460 [<ffffffff8108f69d>] worker_thread+0x11d/0x5b0 [<ffffffff8108f580>] ? rescuer_thread+0x3a0/0x3a0 [<ffffffff81096811>] kthread+0xe1/0x100 [<ffffffff81096730>] ? kthread_create_on_node+0x1a0/0x1a0 [<ffffffff816cc6bc>] ret_from_fork+0x7c/0xb0 [<ffffffff81096730>] ? kthread_create_on_node+0x1a0/0x1a0 This patch fixes this problem by checking if acpi_device->handler is NULL in acpi_scan_hot_remove(). Fixes: d22ddcbc4fb7 (ACPI / hotplug: Add demand_offline hotplug profile flag) Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> [rjw: Subject] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit dee1592638ab7ea35a32179b73f9284dead49c03 upstream.

When ACPI_HOTPLUG_MEMORY is not configured, memory_device_handler.attach
is not set.  In acpi_scan_attach_handler(), the acpi_device->handler will
not be initialized.

In acpi_scan_hot_remove(), it doesn't check if acpi_device->handler is NULL.
If we do memory hot-remove without ACPI_HOTPLUG_MEMORY configured, the kernel
will panic.

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000088
 IP: [<ffffffff813e318f>] acpi_device_hotplug+0x1d7/0x4c4
 PGD 0
 Oops: 0000 [#1] SMP
 Modules linked in: sd_mod(E) sr_mod(E) cdrom(E) crc_t10dif(E) crct10dif_common(E) ata_piix(E) libata(E)
 CPU: 0 PID: 41 Comm: kworker/u2:1 Tainted: G            E 3.16.0-rc7--3.16-rc7-tangchen+ #20
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
 Workqueue: kacpi_hotplug acpi_hotplug_work_fn
 task: ffff8800182436c0 ti: ffff880018254000 task.ti: ffff880018254000
 RIP: 0010:[<ffffffff813e318f>]  [<ffffffff813e318f>] acpi_device_hotplug+0x1d7/0x4c4
 RSP: 0000:ffff880018257da8  EFLAGS: 00000246
 RAX: 0000000000000000 RBX: ffff88001cd8d800 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: ffff88001e40e6f8 RDI: 0000000000000246
 RBP: ffff880018257df0 R08: 0000000000000096 R09: 00000000000011a0
 R10: 63735f6970636120 R11: 725f746f685f6e61 R12: 0000000000000003
 R13: ffff88001cc1c400 R14: ffff88001e062028 R15: 0000000000000040
 FS:  0000000000000000(0000) GS:ffff88001e400000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: 0000000000000088 CR3: 000000001a9a2000 CR4: 00000000000006f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 0000000000000000 DR7: 0000000000000000
 Stack:
  00000000523cab58 ffff88001cd8d9f8 ffff88001852d480 00000000523cab58
  ffff88001852d480 ffff880018221e40 ffff88001cc1c400 ffff88001cce2d00
  0000000000000040 ffff880018257e08 ffffffff813dc31d ffff88001852d480
 Call Trace:
  [<ffffffff813dc31d>] acpi_hotplug_work_fn+0x1e/0x29
  [<ffffffff8108eefb>] process_one_work+0x17b/0x460
  [<ffffffff8108f69d>] worker_thread+0x11d/0x5b0
  [<ffffffff8108f580>] ? rescuer_thread+0x3a0/0x3a0
  [<ffffffff81096811>] kthread+0xe1/0x100
  [<ffffffff81096730>] ? kthread_create_on_node+0x1a0/0x1a0
  [<ffffffff816cc6bc>] ret_from_fork+0x7c/0xb0
  [<ffffffff81096730>] ? kthread_create_on_node+0x1a0/0x1a0

This patch fixes this problem by checking if acpi_device->handler is NULL
in acpi_scan_hot_remove().

Fixes: d22ddcbc4fb7 (ACPI / hotplug: Add demand_offline hotplug profile flag)
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
[rjw: Subject]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge branch 'acpi-enumeration' 2014-06-03T21:12:20+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2014-06-03T21:12:20+00:00 b04c58b1ed26317bfb4b33d3a2d16377fc6acd0f * acpi-enumeration: ACPI / scan: use platform bus type by default for _HID enumeration ACPI / scan: always register ACPI LPSS scan handler ACPI / scan: always register memory hotplug scan handler ACPI / scan: always register container scan handler ACPI / scan: Change the meaning of missing .attach() in scan handlers ACPI / scan: introduce platform_id device PNP type flag ACPI / scan: drop unsupported serial IDs from PNP ACPI scan handler ID list ACPI / scan: drop IDs that do not comply with the ACPI PNP ID rule ACPI / PNP: use device ID list for PNPACPI device enumeration ACPI / scan: .match() callback for ACPI scan handlers 
* acpi-enumeration:
  ACPI / scan: use platform bus type by default for _HID enumeration
  ACPI / scan: always register ACPI LPSS scan handler
  ACPI / scan: always register memory hotplug scan handler
  ACPI / scan: always register container scan handler
  ACPI / scan: Change the meaning of missing .attach() in scan handlers
  ACPI / scan: introduce platform_id device PNP type flag
  ACPI / scan: drop unsupported serial IDs from PNP ACPI scan handler ID list
  ACPI / scan: drop IDs that do not comply with the ACPI PNP ID rule
  ACPI / PNP: use device ID list for PNPACPI device enumeration
  ACPI / scan: .match() callback for ACPI scan handlers