The event code currently holds a spinlock with IRQs disabled while calling
kfifo_to_user(). kfifo_to_user() can generate a page fault though, which means
we have to be able to sleep, which is not possible if the interrupts are
disabled. The good thing is that kfifo handles concurrent read and write access
just fine as long as there is only one reader and one writer, so we do not any
locking to protect against concurrent access from the read and writer thread. It
is possible though that userspace is trying to read from the event FIFO from
multiple concurrent threads, so we need to add locking to protect against this.
This is done using a mutex. The mutex will only protect the kfifo_to_user()
call, it will not protect the waitqueue. This means that multiple threads can be
waiting for new data and once a new event is added to the FIFO all waiting
threads will be woken up. If one of those threads is unable to read any data
(because another thread already read all the data) it will go back to sleep. The
only remaining issue is that now that the clearing of the BUSY flag and the
emptying of the FIFO does no longer happen in one atomic step it is possible
that a event is added to the FIFO after it has been emptied and this sample will
be visible the next time a new event file descriptor is created. To avoid this
rather move the emptying of the FIFO from iio_event_chrdev_release to
iio_event_getfd().
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Get rid of obsolete uses of goto error_ret and some empty lines.
Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Now that all drivers have been converted to the new event config interface we
can remove for the legacy event config interface. Also drop the '_new' suffix
for the event config interface callbacks, since those are the only callbacks
now.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This mostly consists of patches that didn't quite make the last cycle. Lots
of interesting things under review currently.
Core:
- Add devm_iio_device_register/unregister. I took some convincing on whether
there would be many devices that really were simple enough to need no
explicit actions on removal. Turns out there are some.
- Move some stray docs to above the relevant implemenation.
- Drop a redundant repeated check on the fact the trigger has actually changed
when there is a userspace attempt change it.
Drivers:
New drivers
- Freescale MPL3115A2 Pressure / temperature sensor
New functionality
- hid_sensors: add sensitivity support.
DT bindings
- tsl2563
- hmc5843
Cleanups
- Drop unused scan_type from viperboard adc driver.
- devm_iio_device_register used in viperboard, ad5421, ad5755, adis16130,
adxrs450, vcnl4000, adis16220, ad7816, lpc32xx, adt7316, adis16060, isl29018
and ad2s1200. Note that this was proposed in a number of other drivers
and this revealed a number of missorderings in remove functions. Also for
now I have blocked this on any device that any hardware suspend suport on
the basis that we probably want to power down devices if they have no driver
support loaded.
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Merge tag 'iio-for-3.14a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next
Jonathan writes:
First set of new features, drivers and cleanups for IIO in the 3.14 cycle.
This mostly consists of patches that didn't quite make the last cycle. Lots
of interesting things under review currently.
Core:
- Add devm_iio_device_register/unregister. I took some convincing on whether
there would be many devices that really were simple enough to need no
explicit actions on removal. Turns out there are some.
- Move some stray docs to above the relevant implemenation.
- Drop a redundant repeated check on the fact the trigger has actually changed
when there is a userspace attempt change it.
Drivers:
New drivers
- Freescale MPL3115A2 Pressure / temperature sensor
New functionality
- hid_sensors: add sensitivity support.
DT bindings
- tsl2563
- hmc5843
Cleanups
- Drop unused scan_type from viperboard adc driver.
- devm_iio_device_register used in viperboard, ad5421, ad5755, adis16130,
adxrs450, vcnl4000, adis16220, ad7816, lpc32xx, adt7316, adis16060, isl29018
and ad2s1200. Note that this was proposed in a number of other drivers
and this revealed a number of missorderings in remove functions. Also for
now I have blocked this on any device that any hardware suspend suport on
the basis that we probably want to power down devices if they have no driver
support loaded.
Documentation related to function should be placed above
its implementation. Move it accordingly.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This patch enhances the type safety for the kfifo API. It is now safe
to put const data into a non const FIFO and the API will now generate a
compiler warning when reading from the fifo where the destination
address is pointing to a const variable.
As a side effect the kfifo_put() does now expect the value of an element
instead a pointer to the element. This was suggested Russell King. It
make the handling of the kfifo_put easier since there is no need to
create a helper variable for getting the address of a pointer or to pass
integers of different sizes.
IMHO the API break is okay, since there are currently only six users of
kfifo_put().
The code is also cleaner by kicking out the "if (0)" expressions.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For some devices it is possible to configure a hysteresis for threshold (or
similar) events. This patch adds a new hysteresis event info type which allows
for easy creation and read/write handling of the sysfs attribute.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
The event configuration interface of the IIO framework has not been getting the
same attention as other parts. As a result it has not seen the same improvements
as e.g. the channel interface has seen with the introduction of the channel spec
struct. Currently all the event config callbacks take a u64 (the so called event
code) to pass all the different information about for which event the callback
is invoked. The callback function then has to extract the information it is
interested in using some macros with rather long names. Most information encoded
in the event code comes straight from the iio_chan_spec struct the event was
registered for. Since we always have a handle to the channel spec when we call
the event callbacks the first step is to add the channel spec as a parameter to
the event callbacks. The two remaining things encoded in the event code are the
type and direction of the event. Instead of passing them in one parameter, add
one parameter for each of them and remove the eventcode from the event
callbacks. The patch also adds a new iio_event_info parameter to the
{read,write}_event_value callbacks. This makes it possible, similar to the
iio_chan_info_enum for channels, to specify additional properties other than
just the value for an event. Furthermore the new interface will allow to
register shared events. This is e.g. useful if a device allows configuring a
threshold event, but the threshold setting is the same for all channels.
To implement this the patch adds a new iio_event_spec struct which is similar to
the iio_chan_spec struct. It as two field to specify the type and the direction
of the event. Furthermore it has a mask field for each one of the different
iio_shared_by types. These mask fields holds which kind of attributes should be
registered for the event. Creation of the attributes follows the same rules as
the for the channel attributes. E.g. for the separate_mask there will be a
attribute for each channel with this event, for the shared_by_type there will
only be one attribute per channel type. The iio_chan_spec struct gets two new
fields, 'event_spec' and 'num_event_specs', which is used to specify which the
events for this channel. These two fields are going to replace the channel's
event_mask field.
For now both the old and the new event config interface coexist, but over the
few patches all drivers will be converted from the old to the new interface.
Once that is done all code for supporting the old interface will be removed.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
We have the same code to free a IIO device attribute list in multiple place.
This patch adds a new helper function to take care of this and replaces the
custom instances with a call to the helper function. Note that we do not need to
call list_del() for each of the list items since we will never look at any of
the list items nor the list itself again.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Once the device has been unregistered there won't be any new data no matter how
long a userspace application waits, so we might as well wake them up and let
them know.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
If the IIO device has been unregistered return -ENODEV for any further file
operations like read() and ioctl(). This avoids userspace being able to grab new
references to the device.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This resolves the merge problem with two iio drivers that Stephen
Rothwell pointed out.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make sure that the IIO device is not freed while we still have file descriptors
for it.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
IIO uses anon_inode_get() to allocate file descriptors as part
of its ioctls. But those ioctls are lacking a flag argument
allowing userspace to choose options for the newly opened file
descriptor.
In such case it's advised to use O_CLOEXEC by default so that
userspace is allowed to choose, without race, if the file descriptor
is going to be inherited across exec().
KVM usage of anon_inode_getfd() was fixed in a previous patchset [1],
so IIO is the only subsystem using anon_inode_getfd() with a fixed set
of flags not including O_CLOEXEC.
This patch set O_CLOEXEC flag on the event file descriptor created
with anon_inode_getfd() to not leak file descriptors across exec().
Links:
- Secure File Descriptor Handling (Ulrich Drepper, 2008)
http://udrepper.livejournal.com/20407.html
- Excuse me son, but your code is leaking !!! (Dan Walsh, March 2012)
http://danwalsh.livejournal.com/53603.html
- [1] kvm: use anon_inode_getfd() with O_CLOEXEC flag
http://lkml.kernel.org/r/cover.1377372576.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Currently it is not save to call iio_push_event() from hard IRQ context since
the IIO event code uses spin_lock()/spin_unlock() and it is not save to mix
calls to spin_lock()/spin_unlock() from different contexts on the same lock.
E.g. if the lock is being held in iio_event_chrdev_read() and an interrupts
kicks in and the interrupt handler calls iio_push_event() we end uo with a
deadlock.
This patch updates iio_push_event() to use spin_lock_irqsave()/
spin_unlock_irqstrestore(), since it can be called from both IRQ and non-IRQ
context. All other other users of the lock, which are always run in non-IRQ
context, are updated to spin_lock_irq()/spin_unlock_irq().
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
The function __iio_add_event_config_attrs is only called once, by the
function iio_device_register_eventset. If the call fails,
iio_device_register_eventset calls __iio_remove_event_config_attrs. There
is thus no need for __iio_add_event_config_attrs to also call
__iio_remove_event_config_attrs on failure.
A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)
// <smpl>
@r@
identifier f,free,a;
parameter list[n] ps;
type T;
expression e;
@@
f(ps,T a,...) {
... when any
when != a = e
if(...) { ... free(a); ... return ...; }
... when any
}
@@
identifier r.f,r.free;
expression x,a;
expression list[r.n] xs;
@@
* x = f(xs,a,...);
if (...) { ... free(a); ... return ...; }
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
strict_strto* has been deprecated in favor of kstrto*. Use strict_strtouint
respective strict_strtoint, since that is what the functions we pass the
converted values to expect.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
The dev_attr list is initialized in __iio_add_event_config_attrs which
is called only when indio_dev->channels is true. Nevertheless the list
is used unconditionally later in iio_device_register_eventset which
results in a NULL pointer exception. To fix this unconditionally
initialize the list in iio_device_register_eventset.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Replace open-coded instances of getting a iio_dev struct from a device struct
with dev_to_iio_dev().
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Take the core support + the kfifo buffer implentation out of
staging. Whilst we are far from done in improving this subsystem
it is now at a stage where the userspae interfaces (provided by
the core) can be considered stable.
Drivers will follow over a longer time scale.
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Lars-Peter Clausen