<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/include/acpi/acpi_drivers.h, branch v5.0</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>PCI/ACPI: Allow ACPI to be built without CONFIG_PCI set</title>
<updated>2018-12-20T09:19:49+00:00</updated>
<author>
<name>Sinan Kaya</name>
<email>okaya@kernel.org</email>
</author>
<published>2018-12-19T22:46:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5d32a66541c4683456507481a0944ed2985e75c7'/>
<id>5d32a66541c4683456507481a0944ed2985e75c7</id>
<content type='text'>
We are compiling PCI code today for systems with ACPI and no PCI
device present. Remove the useless code and reduce the tight
dependency.

Signed-off-by: Sinan Kaya &lt;okaya@kernel.org&gt;
Acked-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt; # PCI parts
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We are compiling PCI code today for systems with ACPI and no PCI
device present. Remove the useless code and reduce the tight
dependency.

Signed-off-by: Sinan Kaya &lt;okaya@kernel.org&gt;
Acked-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt; # PCI parts
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / EC: Fix regression related to PM ops support in ECDT device</title>
<updated>2017-11-20T23:13:02+00:00</updated>
<author>
<name>Lv Zheng</name>
<email>lv.zheng@intel.com</email>
</author>
<published>2017-09-26T08:54:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a64a62ce9a380213dc9e192f762266d70c9b40ec'/>
<id>a64a62ce9a380213dc9e192f762266d70c9b40ec</id>
<content type='text'>
On platforms (ASUS X550ZE and possibly all ASUS X series) with valid ECDT
EC but invalid DSDT EC, EC PM ops won't be invoked as ECDT EC is not an
ACPI device. Thus the following commit actually removed post-resume
acpi_ec_enable_event() invocation for such platforms, and triggered a
regression on them that after being resumed, EC (actually should be ECDT)
driver stops handling EC events:

 Commit: c2b46d679b30c5c0d7eb47a21085943242bdd8dc
 Subject: ACPI / EC: Add PM operations to improve event handling for resume process

Notice that the root cause actually is "ECDT is not an ACPI device" rather
than "the timing of acpi_ec_enable_event() invocation", this patch fixes
this issue by enumerating ECDT EC as an ACPI device. Due to the existence
of the noirq stage, the ability of tuning the timing of
acpi_ec_enable_event() invocation is still meaningful.

This patch is a little bit different from the posted fix by moving
acpi_config_boot_ec() from acpi_ec_ecdt_start() to acpi_ec_add() to make
sure that EC event handling won't be stopped as long as the ACPI EC driver
is bound. Thus the following sequence shouldn't disable EC event handling:
unbind,suspend,resume,bind.

Fixes: c2b46d679b30 (ACPI / EC: Add PM operations to improve event handling for resume process)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=196847
Reported-by: Luya Tshimbalanga &lt;luya@fedoraproject.org&gt;
Tested-by: Luya Tshimbalanga &lt;luya@fedoraproject.org&gt;
Cc: 4.9+ &lt;stable@vger.kernel.org&gt; # 4.9+
Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On platforms (ASUS X550ZE and possibly all ASUS X series) with valid ECDT
EC but invalid DSDT EC, EC PM ops won't be invoked as ECDT EC is not an
ACPI device. Thus the following commit actually removed post-resume
acpi_ec_enable_event() invocation for such platforms, and triggered a
regression on them that after being resumed, EC (actually should be ECDT)
driver stops handling EC events:

 Commit: c2b46d679b30c5c0d7eb47a21085943242bdd8dc
 Subject: ACPI / EC: Add PM operations to improve event handling for resume process

Notice that the root cause actually is "ECDT is not an ACPI device" rather
than "the timing of acpi_ec_enable_event() invocation", this patch fixes
this issue by enumerating ECDT EC as an ACPI device. Due to the existence
of the noirq stage, the ability of tuning the timing of
acpi_ec_enable_event() invocation is still meaningful.

This patch is a little bit different from the posted fix by moving
acpi_config_boot_ec() from acpi_ec_ecdt_start() to acpi_ec_add() to make
sure that EC event handling won't be stopped as long as the ACPI EC driver
is bound. Thus the following sequence shouldn't disable EC event handling:
unbind,suspend,resume,bind.

Fixes: c2b46d679b30 (ACPI / EC: Add PM operations to improve event handling for resume process)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=196847
Reported-by: Luya Tshimbalanga &lt;luya@fedoraproject.org&gt;
Tested-by: Luya Tshimbalanga &lt;luya@fedoraproject.org&gt;
Cc: 4.9+ &lt;stable@vger.kernel.org&gt; # 4.9+
Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI: Remove FSF mailing addresses</title>
<updated>2015-07-08T00:27:32+00:00</updated>
<author>
<name>Jarkko Nikula</name>
<email>jarkko.nikula@linux.intel.com</email>
</author>
<published>2015-06-26T08:27:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=4c62dbbce902cf2afa88cac89ec67c828160f431'/>
<id>4c62dbbce902cf2afa88cac89ec67c828160f431</id>
<content type='text'>
There is no need to carry potentially outdated Free Software Foundation
mailing address in file headers since the COPYING file includes it.

Signed-off-by: Jarkko Nikula &lt;jarkko.nikula@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is no need to carry potentially outdated Free Software Foundation
mailing address in file headers since the COPYING file includes it.

Signed-off-by: Jarkko Nikula &lt;jarkko.nikula@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / PCI: Stub out pci_acpi_crs_quirks() and make it x86 specific</title>
<updated>2014-05-06T23:09:47+00:00</updated>
<author>
<name>Hanjun Guo</name>
<email>hanjun.guo@linaro.org</email>
</author>
<published>2014-05-06T03:24:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6b90f55f63c75c2c65454aea6703c2ea91b9e372'/>
<id>6b90f55f63c75c2c65454aea6703c2ea91b9e372</id>
<content type='text'>
For pci_acpi_crs_quirks(), ia64 already doesn't use it, and we can
not foresee it should be used in ARM64, so stub out pci_acpi_crs_quirks()
to avoid introducing platform specific dummy stub function.

Signed-off-by: Hanjun Guo &lt;hanjun.guo@linaro.org&gt;
Reviewed-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
For pci_acpi_crs_quirks(), ia64 already doesn't use it, and we can
not foresee it should be used in ARM64, so stub out pci_acpi_crs_quirks()
to avoid introducing platform specific dummy stub function.

Signed-off-by: Hanjun Guo &lt;hanjun.guo@linaro.org&gt;
Reviewed-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / dock: Drop struct acpi_dock_ops and all code related to it</title>
<updated>2014-02-21T23:48:56+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2014-02-21T00:11:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2f16817d87dcd3fc79e0320f6f0bd186b1ae6184'/>
<id>2f16817d87dcd3fc79e0320f6f0bd186b1ae6184</id>
<content type='text'>
Since struct acpi_dock_ops and the code handling it don't have any
users any more after the previous changes, drop that structure and
the code related to it altogether.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since struct acpi_dock_ops and the code handling it don't have any
users any more after the previous changes, drop that structure and
the code related to it altogether.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / dock: Use ACPI device object pointers instead of ACPI handles</title>
<updated>2014-02-21T00:10:09+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2014-02-21T00:10:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3b52b21fa1f44c8956e21dfba645eda959111b5e'/>
<id>3b52b21fa1f44c8956e21dfba645eda959111b5e</id>
<content type='text'>
Rework the ACPI dock station driver to store ACPI device object
pointers instead of ACPI handles in its internal data structures.

The purpose is moslty to make subsequent simplifications possible,
but also this allows the overall code size to be reduced slightly.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Rework the ACPI dock station driver to store ACPI device object
pointers instead of ACPI handles in its internal data structures.

The purpose is moslty to make subsequent simplifications possible,
but also this allows the overall code size to be reduced slightly.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI: Clean up inclusions of ACPI header files</title>
<updated>2013-12-07T00:03:14+00:00</updated>
<author>
<name>Lv Zheng</name>
<email>lv.zheng@intel.com</email>
</author>
<published>2013-12-03T00:49:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8b48463f89429af408ff695244dc627e1acff4f7'/>
<id>8b48463f89429af408ff695244dc627e1acff4f7</id>
<content type='text'>
Replace direct inclusions of &lt;acpi/acpi.h&gt;, &lt;acpi/acpi_bus.h&gt; and
&lt;acpi/acpi_drivers.h&gt;, which are incorrect, with &lt;linux/acpi.h&gt;
inclusions and remove some inclusions of those files that aren't
necessary.

First of all, &lt;acpi/acpi.h&gt;, &lt;acpi/acpi_bus.h&gt; and &lt;acpi/acpi_drivers.h&gt;
should not be included directly from any files that are built for
CONFIG_ACPI unset, because that generally leads to build warnings about
undefined symbols in !CONFIG_ACPI builds.  For CONFIG_ACPI set,
&lt;linux/acpi.h&gt; includes those files and for CONFIG_ACPI unset it
provides stub ACPI symbols to be used in that case.

Second, there are ordering dependencies between those files that always
have to be met.  Namely, it is required that &lt;acpi/acpi_bus.h&gt; be included
prior to &lt;acpi/acpi_drivers.h&gt; so that the acpi_pci_root declarations the
latter depends on are always there.  And &lt;acpi/acpi.h&gt; which provides
basic ACPICA type declarations should always be included prior to any other
ACPI headers in CONFIG_ACPI builds.  That also is taken care of including
&lt;linux/acpi.h&gt; as appropriate.

Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Matthew Garrett &lt;mjg59@srcf.ucam.org&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Acked-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt; (drivers/pci stuff)
Acked-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt; (Xen stuff)
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replace direct inclusions of &lt;acpi/acpi.h&gt;, &lt;acpi/acpi_bus.h&gt; and
&lt;acpi/acpi_drivers.h&gt;, which are incorrect, with &lt;linux/acpi.h&gt;
inclusions and remove some inclusions of those files that aren't
necessary.

First of all, &lt;acpi/acpi.h&gt;, &lt;acpi/acpi_bus.h&gt; and &lt;acpi/acpi_drivers.h&gt;
should not be included directly from any files that are built for
CONFIG_ACPI unset, because that generally leads to build warnings about
undefined symbols in !CONFIG_ACPI builds.  For CONFIG_ACPI set,
&lt;linux/acpi.h&gt; includes those files and for CONFIG_ACPI unset it
provides stub ACPI symbols to be used in that case.

Second, there are ordering dependencies between those files that always
have to be met.  Namely, it is required that &lt;acpi/acpi_bus.h&gt; be included
prior to &lt;acpi/acpi_drivers.h&gt; so that the acpi_pci_root declarations the
latter depends on are always there.  And &lt;acpi/acpi.h&gt; which provides
basic ACPICA type declarations should always be included prior to any other
ACPI headers in CONFIG_ACPI builds.  That also is taken care of including
&lt;linux/acpi.h&gt; as appropriate.

Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Matthew Garrett &lt;mjg59@srcf.ucam.org&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Acked-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt; (drivers/pci stuff)
Acked-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt; (Xen stuff)
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / dock / PCI: Drop ACPI dock notifier chain</title>
<updated>2013-07-14T23:33:12+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2013-07-05T01:03:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f09ce741a03ad7de591aa47e760fbeee28567b63'/>
<id>f09ce741a03ad7de591aa47e760fbeee28567b63</id>
<content type='text'>
The only user of the ACPI dock notifier chain is the ACPI-based PCI
hotplug (acpiphp) driver that uses it to carry out post-dock fixups
needed by some systems with broken _DCK.  However, it is not
necessary to use a separate notifier chain for that, as it can be
simply replaced with a new callback in struct acpi_dock_ops.

For this reason, add a new .fixup() callback to struct acpi_dock_ops
and make hotplug_dock_devices() execute it for all dock devices with
hotplug operations registered.  Accordingly, make acpiphp point that
callback to the function carrying out the post-dock fixups and
do not register a separate dock notifier for each device
registering dock operations.  Finally, drop the ACPI dock notifier
chain that has no more users.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The only user of the ACPI dock notifier chain is the ACPI-based PCI
hotplug (acpiphp) driver that uses it to carry out post-dock fixups
needed by some systems with broken _DCK.  However, it is not
necessary to use a separate notifier chain for that, as it can be
simply replaced with a new callback in struct acpi_dock_ops.

For this reason, add a new .fixup() callback to struct acpi_dock_ops
and make hotplug_dock_devices() execute it for all dock devices with
hotplug operations registered.  Accordingly, make acpiphp point that
callback to the function carrying out the post-dock fixups and
do not register a separate dock notifier for each device
registering dock operations.  Finally, drop the ACPI dock notifier
chain that has no more users.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / dock: Do not check CONFIG_ACPI_DOCK_MODULE</title>
<updated>2013-07-14T23:33:11+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2013-07-05T01:02:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e6c215f15a1cbf4cdd6996d95fba0c0d6c0f3ccc'/>
<id>e6c215f15a1cbf4cdd6996d95fba0c0d6c0f3ccc</id>
<content type='text'>
Since commit 94add0f (ACPI / dock: Initialize ACPI dock subsystem
upfront) the ACPI dock driver cannot be a module, so
CONFIG_ACPI_DOCK_MODULE is never set.  For this reason, simplify
the preprocessor conditional in include/acpi/acpi_drivers.h
referring to that sybbol unnecessarily.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since commit 94add0f (ACPI / dock: Initialize ACPI dock subsystem
upfront) the ACPI dock driver cannot be a module, so
CONFIG_ACPI_DOCK_MODULE is never set.  For this reason, simplify
the preprocessor conditional in include/acpi/acpi_drivers.h
referring to that sybbol unnecessarily.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / dock / PCI: Synchronous handling of dock events for PCI devices</title>
<updated>2013-06-24T09:22:53+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2013-06-24T09:22:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=21a31013f774c726bd199526cd673acc6432b21d'/>
<id>21a31013f774c726bd199526cd673acc6432b21d</id>
<content type='text'>
The interactions between the ACPI dock driver and the ACPI-based PCI
hotplug (acpiphp) are currently problematic because of ordering
issues during hot-remove operations.

First of all, the current ACPI glue code expects that physical
devices will always be deleted before deleting the companion ACPI
device objects.  Otherwise, acpi_unbind_one() will fail with a
warning message printed to the kernel log, for example:

[  185.026073] usb usb5: Oops, 'acpi_handle' corrupt
[  185.035150] pci 0000:1b:00.0: Oops, 'acpi_handle' corrupt
[  185.035515] pci 0000:18:02.0: Oops, 'acpi_handle' corrupt
[  180.013656]  port1: Oops, 'acpi_handle' corrupt

This means, in particular, that struct pci_dev objects have to
be deleted before the struct acpi_device objects they are "glued"
with.

Now, the following happens the during the undocking of an ACPI-based
dock station:
 1) hotplug_dock_devices() invokes registered hotplug callbacks to
    destroy physical devices associated with the ACPI device objects
    depending on the dock station.  It calls dd-&gt;ops-&gt;handler() for
    each of those device objects.
 2) For PCI devices dd-&gt;ops-&gt;handler() points to
    handle_hotplug_event_func() that queues up a separate work item
    to execute _handle_hotplug_event_func() for the given device and
    returns immediately.  That work item will be executed later.
 3) hotplug_dock_devices() calls dock_remove_acpi_device() for each
    device depending on the dock station.  This runs acpi_bus_trim()
    for each of them, which causes the underlying ACPI device object
    to be destroyed, but the work items queued up by
    handle_hotplug_event_func() haven't been started yet.
 4) _handle_hotplug_event_func() queued up in step 2) are executed
    and cause the above failure to happen, because the PCI devices
    they handle do not have the companion ACPI device objects any
    more (those objects have been deleted in step 3).

The possible breakage doesn't end here, though, because
hotplug_dock_devices() may return before at least some of the
_handle_hotplug_event_func() work items spawned by it have a
chance to complete and then undock() will cause _DCK to be
evaluated and that will cause the devices handled by the
_handle_hotplug_event_func() to go away possibly while they are
being accessed.

This means that dd-&gt;ops-&gt;handler() for PCI devices should not point
to handle_hotplug_event_func().  Instead, it should point to a
function that will do the work of _handle_hotplug_event_func()
synchronously.  For this reason, introduce such a function,
hotplug_event_func(), and modity acpiphp_dock_ops to point to
it as the handler.

Unfortunately, however, this is not sufficient, because if the dock
code were not changed further, hotplug_event_func() would now
deadlock with hotplug_dock_devices() that called it, since it would
run unregister_hotplug_dock_device() which in turn would attempt to
acquire the dock station's hp_lock mutex already acquired by
hotplug_dock_devices().

To resolve that deadlock use the observation that
unregister_hotplug_dock_device() won't need to acquire hp_lock
if PCI bridges the devices on the dock station depend on are
prevented from being removed prematurely while the first loop in
hotplug_dock_devices() is in progress.

To make that possible, introduce a mechanism by which the callers of
register_hotplug_dock_device() can provide "init" and "release"
routines that will be executed, respectively, during the addition
and removal of the physical device object associated with the
given ACPI device handle.  Make acpiphp use two new functions,
acpiphp_dock_init() and acpiphp_dock_release(), that call
get_bridge() and put_bridge(), respectively, on the acpiphp bridge
holding the given device, for this purpose.

In addition to that, remove the dock station's list of
"hotplug devices" and make the dock code always walk the whole list
of "dependent devices" instead in such a way that the loops in
hotplug_dock_devices() and dock_event() (replacing the loops over
"hotplug devices") will take references to the list entries that
register_hotplug_dock_device() has been called for.  That prevents
the "release" routines associated with those entries from being
called while the given entry is being processed and for PCI
devices this means that their bridges won't be removed (by a
concurrent thread) while hotplug_event_func() handling them is
being executed.

This change is based on two earlier patches from Jiang Liu.

References: https://bugzilla.kernel.org/show_bug.cgi?id=59501
Reported-and-tested-by: Alexander E. Patrakov &lt;patrakov@gmail.com&gt;
Tracked-down-by: Jiang Liu &lt;jiang.liu@huawei.com&gt;
Tested-by: Illya Klymov &lt;xanf@xanf.me&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Acked-by: Yinghai Lu &lt;yinghai@kernel.org&gt;
Cc: 3.9+ &lt;stable@vger.kernel.org&gt;
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<pre>
The interactions between the ACPI dock driver and the ACPI-based PCI
hotplug (acpiphp) are currently problematic because of ordering
issues during hot-remove operations.

First of all, the current ACPI glue code expects that physical
devices will always be deleted before deleting the companion ACPI
device objects.  Otherwise, acpi_unbind_one() will fail with a
warning message printed to the kernel log, for example:

[  185.026073] usb usb5: Oops, 'acpi_handle' corrupt
[  185.035150] pci 0000:1b:00.0: Oops, 'acpi_handle' corrupt
[  185.035515] pci 0000:18:02.0: Oops, 'acpi_handle' corrupt
[  180.013656]  port1: Oops, 'acpi_handle' corrupt

This means, in particular, that struct pci_dev objects have to
be deleted before the struct acpi_device objects they are "glued"
with.

Now, the following happens the during the undocking of an ACPI-based
dock station:
 1) hotplug_dock_devices() invokes registered hotplug callbacks to
    destroy physical devices associated with the ACPI device objects
    depending on the dock station.  It calls dd-&gt;ops-&gt;handler() for
    each of those device objects.
 2) For PCI devices dd-&gt;ops-&gt;handler() points to
    handle_hotplug_event_func() that queues up a separate work item
    to execute _handle_hotplug_event_func() for the given device and
    returns immediately.  That work item will be executed later.
 3) hotplug_dock_devices() calls dock_remove_acpi_device() for each
    device depending on the dock station.  This runs acpi_bus_trim()
    for each of them, which causes the underlying ACPI device object
    to be destroyed, but the work items queued up by
    handle_hotplug_event_func() haven't been started yet.
 4) _handle_hotplug_event_func() queued up in step 2) are executed
    and cause the above failure to happen, because the PCI devices
    they handle do not have the companion ACPI device objects any
    more (those objects have been deleted in step 3).

The possible breakage doesn't end here, though, because
hotplug_dock_devices() may return before at least some of the
_handle_hotplug_event_func() work items spawned by it have a
chance to complete and then undock() will cause _DCK to be
evaluated and that will cause the devices handled by the
_handle_hotplug_event_func() to go away possibly while they are
being accessed.

This means that dd-&gt;ops-&gt;handler() for PCI devices should not point
to handle_hotplug_event_func().  Instead, it should point to a
function that will do the work of _handle_hotplug_event_func()
synchronously.  For this reason, introduce such a function,
hotplug_event_func(), and modity acpiphp_dock_ops to point to
it as the handler.

Unfortunately, however, this is not sufficient, because if the dock
code were not changed further, hotplug_event_func() would now
deadlock with hotplug_dock_devices() that called it, since it would
run unregister_hotplug_dock_device() which in turn would attempt to
acquire the dock station's hp_lock mutex already acquired by
hotplug_dock_devices().

To resolve that deadlock use the observation that
unregister_hotplug_dock_device() won't need to acquire hp_lock
if PCI bridges the devices on the dock station depend on are
prevented from being removed prematurely while the first loop in
hotplug_dock_devices() is in progress.

To make that possible, introduce a mechanism by which the callers of
register_hotplug_dock_device() can provide "init" and "release"
routines that will be executed, respectively, during the addition
and removal of the physical device object associated with the
given ACPI device handle.  Make acpiphp use two new functions,
acpiphp_dock_init() and acpiphp_dock_release(), that call
get_bridge() and put_bridge(), respectively, on the acpiphp bridge
holding the given device, for this purpose.

In addition to that, remove the dock station's list of
"hotplug devices" and make the dock code always walk the whole list
of "dependent devices" instead in such a way that the loops in
hotplug_dock_devices() and dock_event() (replacing the loops over
"hotplug devices") will take references to the list entries that
register_hotplug_dock_device() has been called for.  That prevents
the "release" routines associated with those entries from being
called while the given entry is being processed and for PCI
devices this means that their bridges won't be removed (by a
concurrent thread) while hotplug_event_func() handling them is
being executed.

This change is based on two earlier patches from Jiang Liu.

References: https://bugzilla.kernel.org/show_bug.cgi?id=59501
Reported-and-tested-by: Alexander E. Patrakov &lt;patrakov@gmail.com&gt;
Tracked-down-by: Jiang Liu &lt;jiang.liu@huawei.com&gt;
Tested-by: Illya Klymov &lt;xanf@xanf.me&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Acked-by: Yinghai Lu &lt;yinghai@kernel.org&gt;
Cc: 3.9+ &lt;stable@vger.kernel.org&gt;
</pre>
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