devm_get_free_pages() and devm_free_pages() are the managed counterparts
for __get_free_pages() and free_pages().
Signed-off-by: NEli Billauer <eli.billauer@gmail.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce devm_kmemdup, which uses resource managed kmalloc.
There are several request from maintainers to add this instead
of using kmemdup.
Signed-off-by: NSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

All device_schedule_callback_owner() users are converted to use
device_remove_file_self().  Remove now unused
{sysfs|device}_schedule_callback_owner().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit d1ba277e.

As reported by Stephen, this patch breaks linux-next as a ppc patch
suddenly (after 2 years) started using this old api call.  So revert it
for now, it will go away in 3.15-rc2 when we can change the PPC call to
the new api.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch introduces "devm_kstrdup" API so that the
device's driver can allocate memory and copy string.
Signed-off-by: NManish Badarkhe <badarkhe.manish@gmail.com>
Signed-off-by: NMark Brown <broonie@linaro.org>

All device_schedule_callback_owner() users are converted to use
device_remove_file_self().  Remove now unused
{sysfs|device}_schedule_callback_owner().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Sometimes it's necessary to implement a node which wants to delete
nodes including itself.  This isn't straightforward because of kernfs
active reference.  While a file operation is in progress, an active
reference is held and kernfs_remove() waits for all such references to
drain before completing.  For a self-deleting node, this is a deadlock
as kernfs_remove() ends up waiting for an active reference that itself
is sitting on top of.

This currently is worked around in the sysfs layer using
sysfs_schedule_callback() which makes such removals asynchronous.
While it works, it's rather cumbersome and inherently breaks
synchronicity of the operation - the file operation which triggered
the operation may complete before the removal is finished (or even
started) and the removal may fail asynchronously.  If a removal
operation is immmediately followed by another operation which expects
the specific name to be available (e.g. removal followed by rename
onto the same name), there's no way to make the latter operation
reliable.

The thing is there's no inherent reason for this to be asynchrnous.
All that's necessary to do this synchronous is a dedicated operation
which drops its own active ref and deactivates self.  This patch
implements kernfs_remove_self() and its wrappers in sysfs and driver
core.  kernfs_remove_self() is to be called from one of the file
operations, drops the active ref the task is holding, removes the self
node, and restores active ref to the dead node so that the ref is
balanced afterwards.  __kernfs_remove() is updated so that it takes an
early exit if the target node is already fully removed so that the
active ref restored by kernfs_remove_self() after removal doesn't
confuse the deactivation path.

This makes implementing self-deleting nodes very easy.  The normal
removal path doesn't even need to be changed to use
kernfs_remove_self() for the self-deleting node.  The method can
invoke kernfs_remove_self() on itself before proceeding the normal
removal path.  kernfs_remove() invoked on the node by the normal
deletion path will simply be ignored.

This will replace sysfs_schedule_callback().  A subtle feature of
sysfs_schedule_callback() is that it collapses multiple invocations -
even if multiple removals are triggered, the removal callback is run
only once.  An equivalent effect can be achieved by testing the return
value of kernfs_remove_self() - only the one which gets %true return
value should proceed with actual deletion.  All other instances of
kernfs_remove_self() will wait till the enclosing kernfs operation
which invoked the winning instance of kernfs_remove_self() finishes
and then return %false.  This trivially makes all users of
kernfs_remove_self() automatically show correct synchronous behavior
even when there are multiple concurrent operations - all "echo 1 >
delete" instances will finish only after the whole operation is
completed by one of the instances.

Note that manipulation of active ref is implemented in separate public
functions - kernfs_[un]break_active_protection().
kernfs_remove_self() is the only user at the moment but this will be
used to cater to more complex cases.

v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing
    and sysfs_remove_file_self() had incorrect return type.  Fix it.
    Reported by kbuild test bot.

v3: kernfs_[un]break_active_protection() separated out from
    kernfs_remove_self() and exposed as public API.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 1ae06819.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit d1ba277e.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

All device_schedule_callback_owner() users are converted to use
device_remove_file_self().  Remove now unused
{sysfs|device}_schedule_callback_owner().
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Sometimes it's necessary to implement a node which wants to delete
nodes including itself.  This isn't straightforward because of kernfs
active reference.  While a file operation is in progress, an active
reference is held and kernfs_remove() waits for all such references to
drain before completing.  For a self-deleting node, this is a deadlock
as kernfs_remove() ends up waiting for an active reference that itself
is sitting on top of.

This currently is worked around in the sysfs layer using
sysfs_schedule_callback() which makes such removals asynchronous.
While it works, it's rather cumbersome and inherently breaks
synchronicity of the operation - the file operation which triggered
the operation may complete before the removal is finished (or even
started) and the removal may fail asynchronously.  If a removal
operation is immmediately followed by another operation which expects
the specific name to be available (e.g. removal followed by rename
onto the same name), there's no way to make the latter operation
reliable.

The thing is there's no inherent reason for this to be asynchrnous.
All that's necessary to do this synchronous is a dedicated operation
which drops its own active ref and deactivates self.  This patch
implements kernfs_remove_self() and its wrappers in sysfs and driver
core.  kernfs_remove_self() is to be called from one of the file
operations, drops the active ref and deactivates using
__kernfs_deactivate_self(), removes the self node, and restores active
ref to the dead node using __kernfs_reactivate_self() so that the ref
is balanced afterwards.  __kernfs_remove() is updated so that it takes
an early exit if the target node is already fully removed so that the
active ref restored by kernfs_remove_self() after removal doesn't
confuse the deactivation path.

This makes implementing self-deleting nodes very easy.  The normal
removal path doesn't even need to be changed to use
kernfs_remove_self() for the self-deleting node.  The method can
invoke kernfs_remove_self() on itself before proceeding the normal
removal path.  kernfs_remove() invoked on the node by the normal
deletion path will simply be ignored.

This will replace sysfs_schedule_callback().  A subtle feature of
sysfs_schedule_callback() is that it collapses multiple invocations -
even if multiple removals are triggered, the removal callback is run
only once.  An equivalent effect can be achieved by testing the return
value of kernfs_remove_self() - only the one which gets %true return
value should proceed with actual deletion.  All other instances of
kernfs_remove_self() will wait till the enclosing kernfs operation
which invoked the winning instance of kernfs_remove_self() finishes
and then return %false.  This trivially makes all users of
kernfs_remove_self() automatically show correct synchronous behavior
even when there are multiple concurrent operations - all "echo 1 >
delete" instances will finish only after the whole operation is
completed by one of the instances.

v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing
    and sysfs_remove_file_self() had incorrect return type.  Fix it.
    Reported by kbuild test bot.

v3: Updated to use __kernfs_{de|re}activate_self().
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Modify struct acpi_dev_node to contain a pointer to struct acpi_device
associated with the given device object (that is, its ACPI companion
device) instead of an ACPI handle corresponding to it.  Introduce two
new macros for manipulating that pointer in a CONFIG_ACPI-safe way,
ACPI_COMPANION() and ACPI_COMPANION_SET(), and rework the
ACPI_HANDLE() macro to take the above changes into account.
Drop the ACPI_HANDLE_SET() macro entirely and rework its users to
use ACPI_COMPANION_SET() instead.  For some of them who used to
pass the result of acpi_get_child() directly to ACPI_HANDLE_SET()
introduce a helper routine acpi_preset_companion() doing an
equivalent thing.

The main motivation for doing this is that there are things
represented by struct acpi_device objects that don't have valid
ACPI handles (so called fixed ACPI hardware features, such as
power and sleep buttons) and we would like to create platform
device objects for them and "glue" them to their ACPI companions
in the usual way (which currently is impossible due to the
lack of valid ACPI handles).  However, there are more reasons
why it may be useful.

First, struct acpi_device pointers allow of much better type checking
than void pointers which are ACPI handles, so it should be more
difficult to write buggy code using modified struct acpi_dev_node
and the new macros.  Second, the change should help to reduce (over
time) the number of places in which the result of ACPI_HANDLE() is
passed to acpi_bus_get_device() in order to obtain a pointer to the
struct acpi_device associated with the given "physical" device,
because now that pointer is returned by ACPI_COMPANION() directly.
Finally, the change should make it easier to write generic code that
will build both for CONFIG_ACPI set and unset without adding explicit
compiler directives to it.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> # on Haswell
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Aaron Lu <aaron.lu@intel.com> # for ATA and SDIO part

dev_WARN() and dev_WARN_ONCE() are annoying because (1) they include
only the driver name, not the device name, and (2) they print a spurious
newline in the middle.  This results in messages like this that are less
useful than they should be:

  [   40.094995] Device pcieport
  disabling already-disabled device

This patch makes them work more like dev_printk().
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, devm_ managed memory only supports kzalloc.

Convert the devm_kzalloc implementation to devm_kmalloc and remove the
complete memset to 0 but still set the initial struct devres header and
whatever padding before data to 0.

Add the other normal alloc variants as static inlines with __GFP_ZERO
added to the gfp flag where appropriate:

	devm_kzalloc
	devm_kcalloc
	devm_kmalloc_array

Add gfp.h to device.h for the newly added static inlines.

akpm: the current API forces us to replace kmalloc() with kzalloc() when
performing devm_ conversions.  This adds a relatively minor overhead.
More significantly, it will defeat kmemcheck used-uninitialized checking,
and for a particular driver, losing used-uninitialised checking for their
core controlling data structures will significantly degrade kmemcheck
usefulness.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Sangjung Woo <sangjung.woo@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

No in-kernel code is now using this, they have all be converted over to
using the bin_attrs support in attribute groups, so this field, and the
code in the driver core that was creating/remove the binary files can be
removed.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that all in-kernel users of the dev_attrs field are converted to use
dev_groups, we can safely remove dev_attrs from struct class.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that all in-kernel users of bus_type.drv_attrs have been converted
to use drv_groups instead, the drv_attrs field, and logic surrounding
it, can be removed.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that all in-kernel users of bus_type.bus_attrs have been converted
to use bus_groups instead, the bus_attrs field, and logic surrounding
it, can be removed.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

sysfs ns (namespace) implementation became more convoluted than
necessary while trying to hide ns information from visible interface.
The relatively recent attr ns support is a good example.

* attr ns tag is determined by sysfs_ops->namespace() callback while
  dir tag is determined by kobj_type->namespace().  The placement is
  arbitrary.

* Instead of performing operations with explicit ns tag, the namespace
  callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(),
  class_attr_namespace(), class_attr->namespace().  It's not simpler
  in any sense.  The only thing this convolution does is traversing
  the whole stack backwards.

The namespace callbacks are unncessary because the operations involved
are inherently synchronous.  The information can be provided in in
straight-forward top-down direction and reversing that direction is
unnecessary and against basic design principles.

This backward interface is unnecessarily convoluted and hinders
properly separating out sysfs from driver model / kobject for proper
layering.  This patch updates attr ns support such that

* sysfs_ops->namespace() and class_attr->namespace() are dropped.

* sysfs_{create|remove}_file_ns(), which take explicit @ns param, are
  added and sysfs_{create|remove}_file() are now simple wrappers
  around the ns aware functions.

* ns handling is dropped from sysfs_chmod_file().  Nobody uses it at
  this point.  sysfs_chmod_file_ns() can be added later if necessary.

* Explicit @ns is propagated through class_{create|remove}_file_ns()
  and netdev_class_{create|remove}_file_ns().

* driver/net/bonding which is currently the only user of attr
  namespace is updated to use netdev_class_{create|remove}_file_ns()
  with @bh->net as the ns tag instead of using the namespace callback.

This patch should be an equivalent conversion without any functional
difference.  It makes the code easier to follow, reduces lines of code
a bit and helps proper separation and layering.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

device_hotplug_lock is held around the acpi_bus_trim() call in
acpi_scan_hot_remove() which generally removes devices (it removes
ACPI device objects at least, but it may also remove "physical"
device objects through .detach() callbacks of ACPI scan handlers).
Thus, potentially, device sysfs attributes are removed under that
lock and to remove those attributes it is necessary to hold the
s_active references of their directory entries for writing.

On the other hand, the execution of a .show() or .store() callback
from a sysfs attribute is carried out with that attribute's s_active
reference held for reading.  Consequently, if any device sysfs
attribute that may be removed from within acpi_scan_hot_remove()
through acpi_bus_trim() has a .store() or .show() callback which
acquires device_hotplug_lock, the execution of that callback may
deadlock with the removal of the attribute.  [Unfortunately, the
"online" device attribute of CPUs and memory blocks is one of them.]

To avoid such deadlocks, make all of the sysfs attribute callbacks
that need to lock device hotplug, for example store_online(), use
a special function, lock_device_hotplug_sysfs(), to lock device
hotplug and return the result of that function immediately if it is
not zero.  This will cause the s_active reference of the directory
entry in question to be released and the syscall to be restarted
if device_hotplug_lock cannot be acquired.

[show_online() actually doesn't need to lock device hotplug, but
it is useful to serialize it with respect to device_offline() and
device_online() for the same device (in case user space attempts to
run them concurrently) which can be done with the help of
device_lock().]
Reported-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reported-and-tested-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
Suggested-by: NTejun Heo <tj@kernel.org>
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>

When DEBUG is defined, dev_dbg_ratelimited uses dynamic debug data
structures even when CONFIG_DYNAMIC_DEBUG is not defined.
It leads to build break.
For example, when I try to use dev_dbg_ratelimited in USB code and
CONFIG_USB_DEBUG is enabled, but CONFIG_DYNAMIC_DEBUG is not, I get:

  CC [M]  drivers/usb/host/xhci-ring.o
  drivers/usb/host/xhci-ring.c: In function ‘xhci_queue_intr_tx’:
  drivers/usb/host/xhci-ring.c:3059:3: error: implicit declaration of function ‘DEFINE_DYNAMIC_DEBUG_METADATA’ [-Werror=implicit-function-declaration]
  drivers/usb/host/xhci-ring.c:3059:3: error: ‘descriptor’ undeclared (first use in this function)
  drivers/usb/host/xhci-ring.c:3059:3: note: each undeclared identifier is reported only once for each function it appears in
  drivers/usb/host/xhci-ring.c:3059:3: error: implicit declaration of function ‘__dynamic_pr_debug’ [-Werror=implicit-function-declaration]
  drivers/usb/host/xhci-ring.c: In function ‘xhci_queue_isoc_tx_prepare’:
  drivers/usb/host/xhci-ring.c:3847:3: error: ‘descriptor’ undeclared (first use in this function)
  cc1: some warnings being treated as errors
  make[2]: *** [drivers/usb/host/xhci-ring.o] Error 1
  make[1]: *** [drivers/usb/host] Error 2
  make: *** [drivers/usb/] Error 2

This patch separates definition for CONFIG_DYNAMIC_DEBUG and DEBUG cases.

[Note, Sarah moved the comment above the macro to avoid checkpatch
warnings.]
Signed-off-by: NDmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch cleans the initialization of dma contiguous framework. The
all-in-one dma_declare_contiguous() function is now separated into
dma_contiguous_reserve_area() which only steals the the memory from
memblock allocator and dma_contiguous_add_device() function, which
assigns given device to the specified reserved memory area. This improves
the flexibility in defining contiguous memory areas and assigning device
to them, because now it is possible to assign more than one device to
the given contiguous memory area. Such split in initialization procedure
is also required for upcoming device tree support.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: NKyungmin Park <kyungmin.park@samsung.com>
Acked-by: NMichal Nazarewicz <mina86@mina86.com>
Acked-by: NTomasz Figa <t.figa@samsung.com>

This creates the macros DRIVER_ATTR_WO() and DEVICE_ATTR_WO() for
write-only attributes for drivers and devices.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

attribute groups are much more flexible than just a list of attributes,
due to their support for visibility of the attributes, and binary
attributes. Add bus_groups to struct bus_type which should be used
instead of bus_attrs.

bus_attrs will be removed from the structure soon.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

attribute groups are much more flexible than just a list of attributes,
due to their support for visibility of the attributes, and binary
attributes. Add drv_groups to struct bus_type which should be used
instead of drv_attrs.

drv_attrs will be removed from the structure soon.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

attribute groups are much more flexible than just a list of attributes,
due to their support for visibility of the attributes, and binary
attributes. Add dev_groups to struct bus_type which should be used
instead of dev_attrs.

dev_attrs will be removed from the structure soon.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We should be using groups, not attribute lists, for classes to allow
subdirectories, and soon, binary files.  Groups are just more flexible
overall, so add them.

The dev_attrs list will go away after all in-kernel users are converted
to use dev_groups.
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

device_create_groups lets callers create devices as well as associated
sysfs attributes with a single call. This avoids race conditions seen
if sysfs attributes on new devices are created later.

[fixed up comment block placement and add checks for printk buffer
formats - gregkh]
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make it easier to create attributes without having to always audit the
mode settings.
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes the below 3 warnings running "make htmldocs",
by adding descriptions for recently added structure members:

DOCPROC Documentation/DocBook/device-drivers.xml
Warning(/work/git.free-electrons.com/users/michael-opdenacker/linux//include/linux/device.h:116): No description found for parameter 'lock_key'
Warning(/work/git.free-electrons.com/users/michael-opdenacker/linux//include/linux/device.h:723): No description found for parameter 'cma_area'
Warning(/work/git.free-electrons.com/users/michael-opdenacker/linux//include/linux/device.h:723): No description found for parameter 'iommu_group'

Don't hesitate to propose better descriptions!
Signed-off-by: NMichael Opdenacker <michael.opdenacker@free-electrons.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In some cases, graceful hot-removal of devices is not possible,
although in principle the devices in question support hotplug.
For example, that may happen for the last CPU in the system or
for memory modules holding kernel memory.

In those cases it is nice to be able to check if the given device
can be gracefully hot-removed before triggering a removal procedure
that cannot be aborted or reversed.  Unfortunately, however, the
kernel currently doesn't provide any support for that.

To address that deficiency, introduce support for offline and
online operations that can be performed on devices, respectively,
before a hot-removal and in case when it is necessary (or convenient)
to put a device back online after a successful offline (that has not
been followed by removal).  The idea is that the offline will fail
whenever the given device cannot be gracefully removed from the
system and it will not be allowed to use the device after a
successful offline (until a subsequent online) in analogy with the
existing CPU offline/online mechanism.

For now, the offline and online operations are introduced at the
bus type level, as that should be sufficient for the most urgent use
cases (CPUs and memory modules).  In the future, however, the
approach may be extended to cover some more complicated device
offline/online scenarios involving device drivers etc.

The lock_device_hotplug() and unlock_device_hotplug() functions are
introduced because subsequent patches need to put larger pieces of
code under device_hotplug_lock to prevent race conditions between
device offline and removal from happening.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NToshi Kani <toshi.kani@hp.com>

Now that devtmpfs is caring about uid/gid, we need to use the correct
internal types so users who have USER_NS enabled will have things work
properly for them.

Thanks to Eric for pointing this out, and the patch review.
Reported-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Some drivers want to tell userspace what uid and gid should be used for
their device nodes, so allow that information to percolate through the
driver core to userspace in order to make this happen.  This means that
some systems (i.e.  Android and friends) will not need to even run a
udev-like daemon for their device node manager and can just rely in
devtmpfs fully, reducing their footprint even more.
Signed-off-by: NKay Sievers <kay@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

ca22e56d (driver-core: implement 'sysdev' functionality for regular
devices and buses) has introduced bus_register macro with a static
key to distinguish different subsys mutex classes.

This however doesn't work for different subsys which use a common
registering function. One example is subsys_system_register (and
mce_device and cpu_device).

In the end this leads to the following lockdep splat:
[  207.271924] ======================================================
[  207.271932] [ INFO: possible circular locking dependency detected ]
[  207.271942] 3.9.0-rc1-0.7-default+ #34 Not tainted
[  207.271948] -------------------------------------------------------
[  207.271957] bash/10493 is trying to acquire lock:
[  207.271963]  (subsys mutex){+.+.+.}, at: [<ffffffff8134af27>] bus_remove_device+0x37/0x1c0
[  207.271987]
[  207.271987] but task is already holding lock:
[  207.271995]  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81046ccf>] cpu_hotplug_begin+0x2f/0x60
[  207.272012]
[  207.272012] which lock already depends on the new lock.
[  207.272012]
[  207.272023]
[  207.272023] the existing dependency chain (in reverse order) is:
[  207.272033]
[  207.272033] -> #4 (cpu_hotplug.lock){+.+.+.}:
[  207.272044]        [<ffffffff810ae329>] lock_acquire+0xe9/0x120
[  207.272056]        [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
[  207.272069]        [<ffffffff81046ba9>] get_online_cpus+0x29/0x40
[  207.272082]        [<ffffffff81185210>] drain_all_stock+0x30/0x150
[  207.272094]        [<ffffffff811853da>] mem_cgroup_reclaim+0xaa/0xe0
[  207.272104]        [<ffffffff8118775e>] __mem_cgroup_try_charge+0x51e/0xcf0
[  207.272114]        [<ffffffff81188486>] mem_cgroup_charge_common+0x36/0x60
[  207.272125]        [<ffffffff811884da>] mem_cgroup_newpage_charge+0x2a/0x30
[  207.272135]        [<ffffffff81150531>] do_wp_page+0x231/0x830
[  207.272147]        [<ffffffff8115151e>] handle_pte_fault+0x19e/0x8d0
[  207.272157]        [<ffffffff81151da8>] handle_mm_fault+0x158/0x1e0
[  207.272166]        [<ffffffff814b6153>] do_page_fault+0x2a3/0x4e0
[  207.272178]        [<ffffffff814b2578>] page_fault+0x28/0x30
[  207.272189]
[  207.272189] -> #3 (&mm->mmap_sem){++++++}:
[  207.272199]        [<ffffffff810ae329>] lock_acquire+0xe9/0x120
[  207.272208]        [<ffffffff8114c5ad>] might_fault+0x6d/0x90
[  207.272218]        [<ffffffff811a11e3>] filldir64+0xb3/0x120
[  207.272229]        [<ffffffffa013fc19>] call_filldir+0x89/0x130 [ext3]
[  207.272248]        [<ffffffffa0140377>] ext3_readdir+0x6b7/0x7e0 [ext3]
[  207.272263]        [<ffffffff811a1519>] vfs_readdir+0xa9/0xc0
[  207.272273]        [<ffffffff811a15cb>] sys_getdents64+0x9b/0x110
[  207.272284]        [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
[  207.272296]
[  207.272296] -> #2 (&type->i_mutex_dir_key#3){+.+.+.}:
[  207.272309]        [<ffffffff810ae329>] lock_acquire+0xe9/0x120
[  207.272319]        [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
[  207.272329]        [<ffffffff8119c254>] link_path_walk+0x6f4/0x9a0
[  207.272339]        [<ffffffff8119e7fa>] path_openat+0xba/0x470
[  207.272349]        [<ffffffff8119ecf8>] do_filp_open+0x48/0xa0
[  207.272358]        [<ffffffff8118d81c>] file_open_name+0xdc/0x110
[  207.272369]        [<ffffffff8118d885>] filp_open+0x35/0x40
[  207.272378]        [<ffffffff8135c76e>] _request_firmware+0x52e/0xb20
[  207.272389]        [<ffffffff8135cdd6>] request_firmware+0x16/0x20
[  207.272399]        [<ffffffffa03bdb91>] request_microcode_fw+0x61/0xd0 [microcode]
[  207.272416]        [<ffffffffa03bd554>] microcode_init_cpu+0x104/0x150 [microcode]
[  207.272431]        [<ffffffffa03bd61c>] mc_device_add+0x7c/0xb0 [microcode]
[  207.272444]        [<ffffffff8134a419>] subsys_interface_register+0xc9/0x100
[  207.272457]        [<ffffffffa04fc0f4>] 0xffffffffa04fc0f4
[  207.272472]        [<ffffffff81000202>] do_one_initcall+0x42/0x180
[  207.272485]        [<ffffffff810bbeff>] load_module+0x19df/0x1b70
[  207.272499]        [<ffffffff810bc376>] sys_init_module+0xe6/0x130
[  207.272511]        [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
[  207.272523]
[  207.272523] -> #1 (umhelper_sem){++++.+}:
[  207.272537]        [<ffffffff810ae329>] lock_acquire+0xe9/0x120
[  207.272548]        [<ffffffff814ae9c4>] down_read+0x34/0x50
[  207.272559]        [<ffffffff81062bff>] usermodehelper_read_trylock+0x4f/0x100
[  207.272575]        [<ffffffff8135c7dd>] _request_firmware+0x59d/0xb20
[  207.272587]        [<ffffffff8135cdd6>] request_firmware+0x16/0x20
[  207.272599]        [<ffffffffa03bdb91>] request_microcode_fw+0x61/0xd0 [microcode]
[  207.272613]        [<ffffffffa03bd554>] microcode_init_cpu+0x104/0x150 [microcode]
[  207.272627]        [<ffffffffa03bd61c>] mc_device_add+0x7c/0xb0 [microcode]
[  207.272641]        [<ffffffff8134a419>] subsys_interface_register+0xc9/0x100
[  207.272654]        [<ffffffffa04fc0f4>] 0xffffffffa04fc0f4
[  207.272666]        [<ffffffff81000202>] do_one_initcall+0x42/0x180
[  207.272678]        [<ffffffff810bbeff>] load_module+0x19df/0x1b70
[  207.272690]        [<ffffffff810bc376>] sys_init_module+0xe6/0x130
[  207.272702]        [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
[  207.272715]
[  207.272715] -> #0 (subsys mutex){+.+.+.}:
[  207.272729]        [<ffffffff810ae002>] __lock_acquire+0x13b2/0x15f0
[  207.272740]        [<ffffffff810ae329>] lock_acquire+0xe9/0x120
[  207.272751]        [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
[  207.272763]        [<ffffffff8134af27>] bus_remove_device+0x37/0x1c0
[  207.272775]        [<ffffffff81349114>] device_del+0x134/0x1f0
[  207.272786]        [<ffffffff813491f2>] device_unregister+0x22/0x60
[  207.272798]        [<ffffffff814a24ea>] mce_cpu_callback+0x15e/0x1ad
[  207.272812]        [<ffffffff814b6402>] notifier_call_chain+0x72/0x130
[  207.272824]        [<ffffffff81073d6e>] __raw_notifier_call_chain+0xe/0x10
[  207.272839]        [<ffffffff81498f76>] _cpu_down+0x1d6/0x350
[  207.272851]        [<ffffffff81499130>] cpu_down+0x40/0x60
[  207.272862]        [<ffffffff8149cc55>] store_online+0x75/0xe0
[  207.272874]        [<ffffffff813474a0>] dev_attr_store+0x20/0x30
[  207.272886]        [<ffffffff812090d9>] sysfs_write_file+0xd9/0x150
[  207.272900]        [<ffffffff8118e10b>] vfs_write+0xcb/0x130
[  207.272911]        [<ffffffff8118e924>] sys_write+0x64/0xa0
[  207.272923]        [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
[  207.272936]
[  207.272936] other info that might help us debug this:
[  207.272936]
[  207.272952] Chain exists of:
[  207.272952]   subsys mutex --> &mm->mmap_sem --> cpu_hotplug.lock
[  207.272952]
[  207.272973]  Possible unsafe locking scenario:
[  207.272973]
[  207.272984]        CPU0                    CPU1
[  207.272992]        ----                    ----
[  207.273000]   lock(cpu_hotplug.lock);
[  207.273009]                                lock(&mm->mmap_sem);
[  207.273020]                                lock(cpu_hotplug.lock);
[  207.273031]   lock(subsys mutex);
[  207.273040]
[  207.273040]  *** DEADLOCK ***
[  207.273040]
[  207.273055] 5 locks held by bash/10493:
[  207.273062]  #0:  (&buffer->mutex){+.+.+.}, at: [<ffffffff81209049>] sysfs_write_file+0x49/0x150
[  207.273080]  #1:  (s_active#150){.+.+.+}, at: [<ffffffff812090c2>] sysfs_write_file+0xc2/0x150
[  207.273099]  #2:  (x86_cpu_hotplug_driver_mutex){+.+.+.}, at: [<ffffffff81027557>] cpu_hotplug_driver_lock+0x17/0x20
[  207.273121]  #3:  (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8149911c>] cpu_down+0x2c/0x60
[  207.273140]  #4:  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81046ccf>] cpu_hotplug_begin+0x2f/0x60
[  207.273158]
[  207.273158] stack backtrace:
[  207.273170] Pid: 10493, comm: bash Not tainted 3.9.0-rc1-0.7-default+ #34
[  207.273180] Call Trace:
[  207.273192]  [<ffffffff810ab373>] print_circular_bug+0x223/0x310
[  207.273204]  [<ffffffff810ae002>] __lock_acquire+0x13b2/0x15f0
[  207.273216]  [<ffffffff812086b0>] ? sysfs_hash_and_remove+0x60/0xc0
[  207.273227]  [<ffffffff810ae329>] lock_acquire+0xe9/0x120
[  207.273239]  [<ffffffff8134af27>] ? bus_remove_device+0x37/0x1c0
[  207.273251]  [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
[  207.273263]  [<ffffffff8134af27>] ? bus_remove_device+0x37/0x1c0
[  207.273274]  [<ffffffff812086b0>] ? sysfs_hash_and_remove+0x60/0xc0
[  207.273286]  [<ffffffff8134af27>] bus_remove_device+0x37/0x1c0
[  207.273298]  [<ffffffff81349114>] device_del+0x134/0x1f0
[  207.273309]  [<ffffffff813491f2>] device_unregister+0x22/0x60
[  207.273321]  [<ffffffff814a24ea>] mce_cpu_callback+0x15e/0x1ad
[  207.273332]  [<ffffffff814b6402>] notifier_call_chain+0x72/0x130
[  207.273344]  [<ffffffff81073d6e>] __raw_notifier_call_chain+0xe/0x10
[  207.273356]  [<ffffffff81498f76>] _cpu_down+0x1d6/0x350
[  207.273368]  [<ffffffff81027557>] ? cpu_hotplug_driver_lock+0x17/0x20
[  207.273380]  [<ffffffff81499130>] cpu_down+0x40/0x60
[  207.273391]  [<ffffffff8149cc55>] store_online+0x75/0xe0
[  207.273402]  [<ffffffff813474a0>] dev_attr_store+0x20/0x30
[  207.273413]  [<ffffffff812090d9>] sysfs_write_file+0xd9/0x150
[  207.273425]  [<ffffffff8118e10b>] vfs_write+0xcb/0x130
[  207.273436]  [<ffffffff8118e924>] sys_write+0x64/0xa0
[  207.273447]  [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b

Which reports a false possitive deadlock because it sees:
1) load_module -> subsys_interface_register -> mc_deveice_add (*) -> subsys->p->mutex -> link_path_walk -> lookup_slow -> i_mutex
2) sys_write -> _cpu_down -> cpu_hotplug_begin -> cpu_hotplug.lock -> mce_cpu_callback -> mce_device_remove(**) -> device_unregister -> bus_remove_device -> subsys mutex
3) vfs_readdir -> i_mutex -> filldir64 -> might_fault -> might_lock_read(mmap_sem) -> page_fault -> mmap_sem -> drain_all_stock -> cpu_hotplug.lock

but
1) takes cpu_subsys subsys (*) but 2) takes mce_device subsys (**) so
the deadlock is not possible AFAICS.

The fix is quite simple. We can pull the key inside bus_type structure
because they are defined per device so the pointer will be unique as
well. bus_register doesn't need to be a macro anymore so change it
to the inline. We could get rid of __bus_register as there is no other
caller but maybe somebody will want to use a different key so keep it
around for now.
Reported-by: NLi Zefan <lizefan@huawei.com>
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Kay tells me the most appropriate place to expose workqueues to
userland would be /sys/devices/virtual/workqueues/WQ_NAME which is
symlinked to /sys/bus/workqueue/devices/WQ_NAME and that we're lacking
a way to do that outside of driver core as virtual_device_parent()
isn't exported and there's no inteface to conveniently create a
virtual subsystem.

This patch implements subsys_virtual_register() by factoring out
subsys_register() from subsys_system_register() and using it with
virtual_device_parent() as the origin directory.  It's identical to
subsys_system_register() other than the origin directory but we aren't
gonna restrict the device names which should be used under it.

This will be used to expose workqueue attributes to userland.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>

Sometimes drivers need to execute one-off actions in their error handling
or device teardown paths. An example would be toggling a GPIO line to
reset the controlled device into predefined state.

To allow performing such actions when using managed resources let's allow
adding them to stack/group of devres resources.
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

All in-kernel users of class_find_device() don't really need mutable
data for match callback.

In two places (kernel/power/suspend_test.c, drivers/scsi/osd/osd_uld.c)
this patch changes match callbacks to use const search data.

The const is propagated to rtc_class_open() and power_supply_get_by_name()
parameters.

Note that there's a dev reference leak in suspend_test.c that's not
touched in this patch.
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This makes the device core auto-grab the pinctrl handle and set
the "default" (PINCTRL_STATE_DEFAULT) state for every device
that is present in the device model right before probe. This will
account for the lion's share of embedded silicon devcies.

A modification of the semantics for pinctrl_get() is also done:
previously if the pinctrl handle for a certain device was already
taken, the pinctrl core would return an error. Now, since the
core may have already default-grabbed the handle and set its
state to "default", if the handle was already taken, this will
be disregarded and the located, previously instanitated handle
will be returned to the caller.

This way all code in drivers explicitly requesting their pinctrl
handlers will still be functional, and drivers that want to
explicitly retrieve and switch their handles can still do that.
But if the desired functionality is just boilerplate of this
type in the probe() function:

struct pinctrl  *p;

p = devm_pinctrl_get_select_default(&dev);
if (IS_ERR(p)) {
   if (PTR_ERR(p) == -EPROBE_DEFER)
        return -EPROBE_DEFER;
        dev_warn(&dev, "no pinctrl handle\n");
}

The discussion began with the addition of such boilerplate
to the omap4 keypad driver:
http://marc.info/?l=linux-input&m=135091157719300&w=2

A previous approach using notifiers was discussed:
http://marc.info/?l=linux-kernel&m=135263661110528&w=2
This failed because it could not handle deferred probes.

This patch alone does not solve the entire dilemma faced:
whether code should be distributed into the drivers or
if it should be centralized to e.g. a PM domain. But it
solves the immediate issue of the addition of boilerplate
to a lot of drivers that just want to grab the default
state. As mentioned, they can later explicitly retrieve
the handle and set different states, and this could as
well be done by e.g. PM domains as it is only related
to a certain struct device * pointer.

ChangeLog v4->v5 (Stephen):
- Simplified the devicecore grab code.
- Deleted a piece of documentation recommending that pins
  be mapped to a device rather than hogged.
ChangeLog v3->v4 (Linus):
- Drop overzealous NULL checks.
- Move kref initialization to pinctrl_create().
- Seeking Tested-by from Stephen Warren so we do not disturb
  the Tegra platform.
- Seeking ACK on this from Greg (and others who like it) so I
  can merge it through the pinctrl subsystem.
ChangeLog v2->v3 (Linus):
- Abstain from using IS_ERR_OR_NULL() in the driver core,
  Russell recently sent a patch to remove it. Handle the
  NULL case explicitly even though it's a bogus case.
- Make sure we handle probe deferral correctly in the device
  core file. devm_kfree() the container on error so we don't
  waste memory for devices without pinctrl handles.
- Introduce reference counting into the pinctrl core using
  <linux/kref.h> so that we don't release pinctrl handles
  that have been obtained for two or more places.
ChangeLog v1->v2 (Linus):
- Only store a pointer in the device struct, and only allocate
  this if it's really used by the device.

Cc: Felipe Balbi <balbi@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Mitch Bradley <wmb@firmworks.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Rickard Andersson <rickard.andersson@stericsson.com>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
[swarren: fixed and simplified error-handling in pinctrl_bind_pins(), to
correctly handle deferred probe. Removed admonition from docs not to use
pinctrl hogs for devices]
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

The devm_request_and_ioremap() function is very useful and helps avoid a
whole lot of boilerplate. However, one issue that keeps popping up is
its lack of a specific error code to determine which of the steps that
it performs failed. Furthermore, while the function gives an example and
suggests what error code to return on failure, a wide variety of error
codes are used throughout the tree.

In an attempt to fix these problems, this patch adds a new function that
drivers can transition to. The devm_ioremap_resource() returns a pointer
to the remapped I/O memory on success or an ERR_PTR() encoded error code
on failure. Callers can check for failure using IS_ERR() and determine
its cause by extracting the error code using PTR_ERR().

devm_request_and_ioremap() is implemented as a wrapper around the new
API and return NULL on failure as before. This ensures that backwards
compatibility is maintained until all users have been converted to the
new API, at which point the old devm_request_and_ioremap() function
should be removed.

A semantic patch is included which can be used to convert from the old
devm_request_and_ioremap() API to the new devm_ioremap_resource() API.
Some non-trivial cases may require manual intervention, though.
Signed-off-by: NThierry Reding <thierry.reding@avionic-design.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

To avoid adding an ACPI handle pointer to struct device on
architectures that don't use ACPI, or generally when CONFIG_ACPI is
not set, in which cases that pointer is useless, define struct
acpi_dev_node that will contain the handle pointer if CONFIG_ACPI is
set and will be empty otherwise and use it to represent the ACPI
device node field in struct device.

In addition to that define macros for reading and setting the ACPI
handle of a device that don't generate code when CONFIG_ACPI is
unset.  Modify the ACPI subsystem to use those macros instead of
referring to the given device's ACPI handle directly.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>