The __iio_buffer_free_sysfs_and_mask() function will be used in
iio_buffer_alloc_sysfs_and_mask() when multiple buffers will be attached to
the IIO device.
This will need to be used to cleanup resources on each buffer, when the
buffers cleanup unwind will occur on the error path.

The move is done in this patch to make the patch that adds multiple buffers
per IIO device a bit cleaner.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-18-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

In order to keep backwards compatibility with the current chardev
mechanism, and in order to add support for multiple buffers per IIO device,
we need to pass both the IIO device & IIO buffer to the chardev.

This is particularly needed for the iio_buffer_read_outer() function, where
we need to pass another buffer object than 'indio_dev->buffer'.

Since we'll also open some chardevs via anon inodes, we can pass extra
buffers in that function by assigning another object to the
iio_dev_buffer_pair object.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-17-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This change wraps all buffer attributes into iio_dev_attr objects, and
assigns a reference to the IIO buffer they belong to.

With the addition of multiple IIO buffers per one IIO device, we need a way
to know which IIO buffer is being enabled/disabled/controlled.

We know that all buffer attributes are device_attributes. So we can wrap
them with a iio_dev_attr types. In the iio_dev_attr type, we can also hold
a reference to an IIO buffer.
So, we end up being able to allocate wrapped attributes for all buffer
attributes (even the one from other drivers).

The neat part with this mechanism, is that we don't need to add any extra
cleanup, because these attributes are being added to a dynamic list that
will get cleaned up via iio_free_chan_devattr_list().

With this change, the 'buffer->scan_el_dev_attr_list' list is being renamed
to 'buffer->buffer_attr_list', effectively merging (or finalizing the
merge) of the buffer/ & scan_elements/ attributes internally.

Accessing these new buffer attributes can now be done via
'to_iio_dev_attr(attr)->buffer' inside the show/store handlers.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-15-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This change adds a reference to a 'struct iio_buffer' object on the
iio_dev_attr object. This way, we can use the created iio_dev_attr objects
on per-buffer basis (since they're allocated anyway).

A minor downside of this change is that the number of parameters on
__iio_add_chan_devattr() grows by 1. This looks like it could do with a bit
of a re-think.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-14-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

With this change, we create a new directory for the IIO device called
buffer0, under which both the old buffer/ and scan_elements/ are stored.

This is done to simplify the addition of multiple IIO buffers per IIO
device. Otherwise we would need to add a bufferX/ and scan_elementsX/
directory for each IIO buffer.
With the current way of storing attribute groups, we can't have directories
stored under each other (i.e. scan_elements/ under buffer/), so the best
approach moving forward is to merge their attributes.

The old/legacy buffer/ & scan_elements/ groups are not stored on the opaque
IIO device object. This way the IIO buffer can have just a single
attribute_group object, saving a bit of memory when adding multiple IIO
buffers.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-13-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

If we want to merge the attributes of the buffer/ and scan_elements/
directories, we'll need to count all attributes first, then (depending on
the attribute group) either allocate 2 attribute groups, or a single one.
Historically an IIO buffer was described by 2 subdirectories under
/sys/bus/iio/iio:devicesX (i.e. buffer/ and scan_elements/); these subdirs
were actually 2 separate attribute groups on the iio_buffer object.

Moving forward, if we want to allow more than one buffer per IIO device,
keeping 2 subdirectories for each IIO buffer is a bit cumbersome
(especially for userpace ABI). So, we will merge the attributes of these 2
subdirs under a /sys/bus/iio/iio:devicesX/bufferY subdirectory. To do this,
we need to count all attributes first, and then distribute them based on
which buffer this is. For the first buffer, we'll need to also allocate the
legacy 2 attribute groups (for buffer/ and scan_elements/), and also a
/sys/bus/iio/iio:devicesX/buffer0 attribute group.

For buffer1 and above, just a single attribute group will be allocated (the
merged one).
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-12-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Up until now, the device groups that an IIO device had were limited to 6.
Two of these groups would account for buffer attributes (the buffer/ and
scan_elements/ directories).

Since we want to add multiple buffers per IIO device, this number may not
be enough, when adding a second buffer. So, this change reallocates the
groups array whenever an IIO device group is added, via a
iio_device_register_sysfs_group() helper.

This also means that the groups array should be assigned to
'indio_dev.dev.groups' really late, right before {cdev_}device_add() is
called to do the entire setup.
And we also must take care to free this array when the sysfs resources are
being cleaned up.

With this change we can also move the 'groups' & 'groupcounter' fields to
the iio_dev_opaque object. Up until now, this didn't make a whole lot of
sense (especially since we weren't sure how multibuffer support would look
like in the end).
But doing it now kills one birds with one stone.

An alternative, would be to add a configurable Kconfig symbol
CONFIG_IIO_MAX_BUFFERS_PER_DEVICE (or something like that) and compute a
static maximum of the groups we can support per IIO device. But that would
probably annoy a few people since that would make the system less
configurable.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-11-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

When updating the buffer demux, we will skip a scan element from the
device in the case `in_ind != out_ind` and we enter the while loop.
in_ind should only be refreshed with `find_next_bit()` in the end of the
loop.

Note, to cause problems we need a situation where we are skippig over
an element (channel not enabled) that happens to not have the same size
as the next element.   Whilst this is a possible situation we haven't
actually identified any cases in mainline where it happens as most drivers
have consistent channel storage sizes with the exception of the timestamp
which is the last element and hence never skipped over.

Fixes: 5ada4ea9 ("staging:iio: add demux optionally to path from device to buffer")
Signed-off-by: NNuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20201112144323.28887-1-nuno.sa@analog.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

The iio_buffer_set_attrs() is no longer used in the drivers, so it can be
removed now.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200929125949.69934-10-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Currently the iio_buffer_{alloc,free}_sysfs_and_mask() take 'indio_dev' as
primary argument. This change splits the main logic into a private function
that takes an IIO buffer as primary argument.

That way, the functions can be extended to configure the sysfs for multiple
buffers.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200917125951.861-1-alexandru.ardelean@analog.comSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

The original patch was error-ed by the submitter (me) and not by the author
(Lars).
After looking through the discussion logs (on email), it seems that this
order was wrong for the start, even though the order implemented in the
drivers was correct.

Discussions:
- first RFC: https://lore.kernel.org/linux-iio/20180622135322.3459-1-alexandru.ardelean@analog.com/
- 2nd patch: https://lore.kernel.org/linux-iio/20181219140912.22582-1-alexandru.ardelean@analog.com/
- final patch-sets:
  https://lore.kernel.org/linux-iio/20200522104632.517470-1-alexandru.ardelean@analog.com/
  https://lore.kernel.org/linux-iio/20200525113855.178821-1-alexandru.ardelean@analog.com/

The last one was applied.

The idea is that pollfunc should be attached before calling the
'indio_dev->setup_ops->postenable' hook and should be detached after
calling the 'indio_dev->setup_ops->predisable' hook.

While the drivers were updated to take this into account, the change to the
IIO core was somehow omitted and was made wrong.

This change fixes the order to the proper form.

Fixes f11d59d8: ("iio: Move attach/detach of the poll func to the core")
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This change moves the 'buffer_list' away from the public IIO device object
into the private part.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

All devices using a triggered buffer need to attach and detach the trigger
to the device in order to properly work. Instead of doing this in each and
every driver by hand move this into the core.

At this point in time, all drivers should have been resolved to
attach/detach the poll-function in the same order.

This patch removes all explicit calls of iio_triggered_buffer_postenable()
& iio_triggered_buffer_predisable() in all drivers, since the core handles
now the pollfunc attach/detach.

The more peculiar change is for the 'at91-sama5d2_adc' driver, since it's
not immediately obvious that removing the hooks doesn't break anything.
Eugen was able to test on at91-sama5d2-adc driver, sama5d2-xplained board.
All seems to be fine.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Tested-by: Eugen Hristev <eugen.hristev@microchip.com> #for at91-sama5d2-adc
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

The variable no longer does anything.
It should have been removed with commit 2e036804 ("iio: buffer: remove
'scan_el_attrs' attribute group from buffer struct").
That was about the last time this was needed.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

It is clear that we transition to INDIO_DIRECT_MODE when disabling the
buffer(s) and it is also clear that we transition from INDIO_DIRECT_MODE
when enabling the buffer(s). So leaving the currentmode field
INDIO_DIRECT_MODE until after the preenable() callback and updating it to
INDIO_DIRECT_MODE before the postdisable() callback doesn't add additional
value. On the other hand some drivers will need to perform different
actions depending on which mode the device is going to operate in/was
operating in.

Moving the update of currentmode before preenable() and after postdisable()
enables us to have drivers which perform mode dependent actions in those
callbacks.

Note, was originally not intended as such, but fixes an issue introduced
in the at91-sama5d2 adc driver.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Fixes: 065056cb ("iio: at91-sama5d2_adc: split at91_adc_current_chan_is_touch() helper")
Tested-by: NEugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This change is both cosmetic and a prequel to adding support for attaching
multiple buffers per IIO device.

The IIO buffer sysfs attrs are mostly designed to support only one attached
buffer, and in order to support more, we need to centralize [in each attr
function] the buffer which is being accessed.

This also makes it a bit more uniform, as in some functions there is a
short-hand 'buffer' variable and at the same time the 'indio_dev->buffer'
is still access directly.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This field doesn't seem used. It seems that only 'buffer->attrs' was ever
used to extend sysfs attributes for an IIO buffer.

Moving forward, it may not make sense to keep it. This patch removes the
field and it's initialization code.

Since we want to rework IIO buffer, to be able to add more buffers per IIO
device, we will merge [somehow] the 'buffer' & 'scan_elements' groups, and
we will continue to add the attributes to the 'buffer' group.

Removing it here, will also make the rework here a bit smaller, since
this code will not be present.
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Before activating a buffer make sure that at least one channel is enabled.
Activating a buffer with 0 channels enabled doesn't make too much sense and
disallowing this case makes sure that individual driver don't have to add
special case code to handle it.

Currently, without this patch enabling a buffer is possible and no error is
produced. With this patch -EINVAL is returned.

An example of execution with this patch and some instrumented print-code:
   root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
   root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
   0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask 00000000
   1: iio_verify_update 753
   2:__iio_update_buffers 1115 ret -22
   3: iio_buffer_store_enable 1241 ret -22
   -bash: echo: write error: Invalid argument
1, 2 & 3 are exit-error paths. 0 the first print in iio_verify_update()
rergardless of error path.

Without this patch (and same instrumented print-code):
   root@analog:~# cd /sys/bus/iio/devices/iio\:device3/buffer
   root@analog:/sys/bus/iio/devices/iio:device3/buffer# echo 1 > enable
   0: iio_verify_update 748 indio_dev->masklength 2 *insert_buffer->scan_mask 00000000
   root@analog:/sys/bus/iio/devices/iio:device3/buffer#
Buffer is enabled with no error.

Note from Jonathan: Probably not suitable for automatic application to stable.
This has been there from the very start.  It tidies up an odd corner
case but won't effect any 'real' users.

Fixes: 84b36ce5 ("staging:iio: Add support for multiple buffers")
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Commit 3862828a ("iio: buffer: Switch to bitmap_zalloc()") introduced
bitmap_alloc(), but commit 20ea39ef ("iio: Fix scan mask selection")
reverted it.

This change adds it back. The only difference is that it's adding
bitmap_zalloc(). There might be some changes later that would require
initializing it to zero. In any case, now it's already zero-ing the
trialmask.

Appears to have been the result of merge conflict resolution rather
than an intentional revert.
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Previous versions of `iio_compute_scan_bytes` only aligned each element
to its own length (i.e. its own natural alignment). Because multiple
consecutive sets of scan elements are buffered this does not work in
case the computed scan bytes do not align with the natural alignment of
the first scan element in the set.

This commit fixes this by aligning the scan bytes to the natural
alignment of the largest scan element in the set.

Fixes: 959d2952 ("staging:iio: make iio_sw_buffer_preenable much more general.")
Signed-off-by: NLars Möllendorf <lars.moellendorf@plating.de>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

It is implied that 'read' will read the first n bytes and not e.g. bytes
only from offsets within the buffer that are a prime number.

This change is non-functional, mostly just a rename.
A secondary intent with this patch is to make room later to add a write
callback.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NEnrico Weigelt <info@metux.net>
Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: NAllison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Switch to bitmap_zalloc() to show clearly what we are allocating.
Besides that it returns pointer of bitmap type instead of opaque void *.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

The trialmask is expected to have all bits set to 0 after allocation.
Currently kmalloc_array() is used which does not zero the memory and so
random bits are set. This results in random channels being enabled when
they shouldn't. Replace kmalloc_array() with kcalloc() which has the same
interface but zeros the memory.

Note the fix is actually required earlier than the below fixes tag, but
will require a manual backport due to move from kmalloc to kmalloc_array.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NAlexandru Ardelean <alexandru.ardelean@analog.com>
Fixes commit 057ac1ac ("iio: Use kmalloc_array() in iio_scan_mask_set()").
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

If no iio buffer has been set up and poll is called return 0.
Without this check there will be a null pointer dereference when
calling poll on a iio driver without an iio buffer.

Cc: stable@vger.kernel.org
Signed-off-by: NStefan Windfeldt-Prytz <stefan.windfeldt@axis.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a sysfs attribute that exposes buffer data available to userspace.
This attribute can be checked at runtime to determine the overall buffer
fill level (across all allocated buffers).
Signed-off-by: NMatt Fornero <matt.fornero@mathworks.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

Fix up affected files that include this signal functionality via sched.h.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

buffer.h supplies everything needed for devices using buffers.
buffer_impl.h supplies access to the internals as needed to write
a buffer implementation.

This was really motivated by the mess that turned up in the
kernel-doc documentation pulled in by the new sphinx docs.
It made it clear that our logical separations in headers were
generally terrible.  The buffer case was easy to sort out without
greatly effecting drivers so here it is.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

This is a precursor to the splitting of buffer.h into parts relevant
to buffer implementation vs those for devices using buffers.
struct buffer is about to become opaque as far as the header is
concerned.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

Ancient legacy of me doing it wrong which it is nice to clear
up whilst we are here.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

Nothing uses it outside of core code.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

This is a necessary step in taking the buffer implementation
opaque.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

Nothing outside of indiustrialio-buffer.c should be using this.
Requires a large amount of juggling of functions to avoid a
forward definition.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

A multiplication for the size determination of a memory allocation
indicated that an array data structure should be processed.
Thus use the corresponding function "kmalloc_array".

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

A recent fix to iio_buffer_read_first_n_outer removed ret from being set by
a return from wait_event_interruptible and also added a continue in a loop
which causes the variable ret to not be set when it reaches the end of the
loop.  Fix this by initializing ret to zero.

Also remove extraneous white space at the end of the loop.

Fixes: fcf68f3c ("fix sched WARNING "do not call blocking ops when !TASK_RUNNING")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

When using CONFIG_DEBUG_ATOMIC_SLEEP, the scheduler nicely points out
that we're calling sleeping primitives within the wait_event loop, which
means we might clobber the task state:

[   10.831289] do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffc00026b610>]
[   10.845531] ------------[ cut here ]------------
[   10.850161] WARNING: at kernel/sched/core.c:7630
...
[   12.164333] ---[ end trace 45409966a9a76438 ]---
[   12.168942] Call trace:
[   12.171391] [<ffffffc00024ed44>] __might_sleep+0x64/0x90
[   12.176699] [<ffffffc000954774>] mutex_lock_nested+0x50/0x3fc
[   12.182440] [<ffffffc0007b9424>] iio_kfifo_buf_data_available+0x28/0x4c
[   12.189043] [<ffffffc0007b76ac>] iio_buffer_ready+0x60/0xe0
[   12.194608] [<ffffffc0007b7834>] iio_buffer_read_first_n_outer+0x108/0x1a8
[   12.201474] [<ffffffc000370d48>] __vfs_read+0x58/0x114
[   12.206606] [<ffffffc000371740>] vfs_read+0x94/0x118
[   12.211564] [<ffffffc0003720f8>] SyS_read+0x64/0xb4
[   12.216436] [<ffffffc000203cb4>] el0_svc_naked+0x24/0x28

To avoid this, we should (a la https://lwn.net/Articles/628628/) use the
wait_woken() function, which avoids the nested sleeping while still
handling races between waiting / wake-events.
Signed-off-by: NBrian Norris <briannorris@chromium.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>
Cc: <Stable@vger.kernel.org> # 3.19+ for introduction of wake_woken
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

config structure is set to 0 when updating the buffers, so by
default config->watermark will be 0. When computing the minimum
between config->watermark and the buffer->watermark or
insert_buffer-watermark, this will always be 0 regardless of the
value set by the user for the buffer.

Set as initial value for config->watermark the maximum allowed
value so that the minimum value will always be set from one of the
buffers.
Signed-off-by: NIrina Tirdea <irina.tirdea@intel.com>
Fixes: f0566c0c ("iio: Set device watermark based on watermark of all
attached buffers")
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

We have the same code for computing the scan index storage size in bytes
all over the place. Factor this out into helper functions.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Acked-by: NDaniel Baluta <daniel.baluta@intel.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>