Jonathan writes:

First round of IIO fixes for the 4.8 cycle.

This is somewhat of a bumper set due to my unavailabilty earlier in the
month.  The only slightly unusual ones are the dts updates for the
rockchip adc reset.  The fix in the driver only makes sense with these
and the rockchip maintainer is happy with them going through IIO to
reach mainline.

Core stuff

* Fix an issue with a blocking op when !TASK_RUNNING. This been there
  a while and snuck in with seemingly minor additions to some core
  code paths.
* Tools
  - generic_buffer failed to initialize the channel array pointer thus
    in the case of no channels blows up trying to free a random memory
    address.
* sw-trigger:
  - Fix config group initialization when configfs is built as a module.

Drivers

* ad5933
  - Fix an incorrect overwrite of an error value.
* ad799x
  - A missed assignment of the update_scan_mode callback means buffered mode
    doesn't work on the ad7991, ad7995 or ad7999.
* ads1015
  - wrong pointer returned from i2c_get_clientdata (missmatch of assumptions)
* am2315
  - Timestamps are reported, but never actually acquired from anywhere
    (so always 0)
  - missing buffer selects in Kconfig
* am335x adc
  - Protect fifo1 from concurrent access.
  - Increase timeout waiting for ADC to be long enough in all cases.
* as3935
  - Timestamps are reported, but never actually acquired from anywhere
    (so always 0)
* at91
  - Fix reading of channel 3.
* atlas-ph-sensor
  - Typo means that the scale of electrical conductivity readings is way off.
* bma220
  - Timestamps are reported, but never actually acquired from anywhere
    (so always 0)
  - Missing buffer selects in Kconfig
* bmp280
  - pass the write pointer to PTR_ERR (i.e. the one that was just checked
    with IS_ERR).
  - suspend /resume crash due to wrong assumption about what dev_get_drvdata
    would return.
* hdc100x
  - It superficially appeared that smbus_read_byte commands would allow
  reading of the outputs in two goes.  In reality it doesn't work, but
  instead returns the same for the upper and lower bytes (nice catch from
  Alison!)
* kxsd9
  - Fix raw read return value to ensure it actually reports the value rather
  than a blank string.
* max44000
  - Missing buffer selects in Kconfig
* rockchip_saradc
  - Add use of reset controller to enforce a clean state of the ADC.
    Some bootloaders can leave it in an 'intersting' state and effectively
    frozen without this. A couple of associated dts updates.
* stk8ba50
  - Missing buffer selects in Kconfig
* stx104
  - Fix a possible race due to use of devm_iio_device_register when there
    was other stuff in the remove function.

The current check for associatedsta being set to -1 to indicate it has
not been found is not working because associatedsta is initialized to
zero and will never be -1.  Fix this by initializing it to ~0 and checking
for ~0 instead.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We can't pass NULL pointers to destroy_workqueue().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix incorrect usage of completion interface by replacing
'wait_for_completion' with 'complete'. This error was introduced
accidentally while replacing semaphores with mutexes.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Binoy Jayan <binoy.jayan@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit ebb657babfa9 ("staging: comedi: ni_mio_common: clarify the
cmd->start_arg validation and use") introduced a backwards compatibility
issue in the use of asynchronous commands on the AO subdevice when
`start_src` is `TRIG_EXT`.  Valid values for `start_src` are `TRIG_INT`
(for internal, software trigger), and `TRIG_EXT` (for external trigger).
When set to `TRIG_EXT`.  In both cases, the driver relies on an
internal, software trigger to set things up (allowing the user
application to write sufficient samples to the data buffer before the
trigger), so it acts as a software "pre-trigger" in the `TRIG_EXT` case.
The software trigger is handled by `ni_ao_inttrig()`.

Prior to the above change, when `start_src` was `TRIG_INT`, `start_arg`
was required to be 0, and `ni_ao_inttrig()` checked that the software
trigger number was also 0.  After the above change, when `start_src` was
`TRIG_INT`, any value was allowed for `start_arg`, and `ni_ao_inttrig()`
checked that the software trigger number matched this `start_arg` value.
The backwards compatibility issue is that the internal trigger number
now has to match `start_arg` when `start_src` is `TRIG_EXT` when it
previously had to be 0.

Fix the backwards compatibility issue in `ni_ao_inttrig()` by always
allowing software trigger number 0 when `start_src` is something other
than `TRIG_INT`.

Thanks to Spencer Olson for reporting the issue.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reported-by: Spencer Olson <olsonse@umich.edu>
Fixes: ebb657babfa9 ("staging: comedi: ni_mio_common: clarify the cmd->start_arg validation and use")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bitwise | has higher precedence than ?: so we need to add some
parenthesis for this to work as intended.

Fixes: 7c9574090d30 ('staging: comedi: dt2811: simplify A/D reference configuration')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The CMDF_ROUND_DOWN case falls through and so always returns -EINVAL.

Fixes: 14b93bb6bbf0 ("staging: comedi: adv_pci_dio: separate out PCI-1760 support")
Signed-off-by: Phil Turnbull <phil.turnbull@oracle.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For counter subdevices, the `s->insn_write` handler is being set to the
wrong function, `ni_tio_insn_read()`.  It should be
`ni_tio_insn_write()`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reported-by: Éric Piel <piel@delmic.com>
Fixes: 10f74377eec3 ("staging: comedi: ni_tio: make ni_tio_winsn() a
  proper comedi (*insn_write)"
Cc: <stable@vger.kernel.org> # 3.17+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 73e0e4dfed4c ("staging: comedi: comedi_test: fix timer lock-up")
fixed a lock-up in the timer routine `waveform_ai_timer()` (which was
called `waveform_ai_interrupt()` at the time) caused by
commit 240512474424 ("staging: comedi: comedi_test: use
comedi_handle_events()").  However, it introduced a race condition that
can result in the timer routine misbehaving, such as accessing freed
memory or dereferencing a NULL pointer.

73e0... changed the timer routine to do nothing unless a
`WAVEFORM_AI_RUNNING` flag was set, and changed `waveform_ai_cancel()`
to clear the flag and replace a call to `del_timer_sync()` with a call
to `del_timer()`.  `waveform_ai_cancel()` may be called from the timer
routine itself (via `comedi_handle_events()`), or from `do_cancel()`.
(`do_cancel()` is called as a result of a file operation (usually a
`COMEDI_CANCEL` ioctl command, or a release), or during device removal.)
When called from `do_cancel()`, the call to `waveform_ai_cancel()` is
followed by a call to `do_become_nonbusy()`, which frees up stuff for
the current asynchronous command under the assumption that it is now
safe to do so.  The race condition occurs when the timer routine
`waveform_ai_timer()` checks the `WAVEFORM_AI_RUNNING` flag just before
it is cleared by `waveform_ai_cancel()`, and is still running during the
call to `do_become_nonbusy()`.  In particular, it can lead to a NULL
pointer dereference:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffffc0c63add>] waveform_ai_timer+0x17d/0x290 [comedi_test]

That corresponds to this line in `waveform_ai_timer()`:

		unsigned int chanspec = cmd->chanlist[async->cur_chan];

but `do_become_nonbusy()` frees `cmd->chanlist` and sets it to `NULL`.

Fix the race by calling `del_timer_sync()` instead of `del_timer()` in
`waveform_ai_cancel()` when not in an interrupt context.  The only time
`waveform_ai_cancel()` is called in an interrupt context is when it is
called from the timer routine itself, via `comedi_handle_events()`.

There is no longer any need for the `WAVEFORM_AI_RUNNING` flag, so get
rid of it.

The bug was copied from the AI subdevice to the AO when support for
commands on the AO subdevice was added by commit 0cf55bbef2f9 ("staging:
comedi: comedi_test: implement commands on AO subdevice").  That
involves the timer routine `waveform_ao_timer()`, the comedi "cancel"
routine `waveform_ao_cancel()`, and the flag `WAVEFORM_AO_RUNNING`.  Fix
it in the same way as for the AI subdevice.

Fixes: 73e0e4dfed4c ("staging: comedi: comedi_test: fix timer lock-up")
Fixes: 0cf55bbef2f9 ("staging: comedi: comedi_test: implement commands
 on AO subdevice")
Reported-by: Éric Piel <piel@delmic.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: <stable@vger.kernel.org> # 4.4+
Cc: Éric Piel <piel@delmic.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

`daqboard2000_find_boardinfo()` is supposed to check if the
DaqBoard/2000 series model is supported, based on the PCI subvendor and
subdevice ID.  The current code is wrong as it is comparing the PCI
device's subdevice ID to an expected, fixed value for the subvendor ID.
It should be comparing the PCI device's subvendor ID to this fixed
value.  Correct it.

Fixes: 7e8401b23e7f ("staging: comedi: daqboard2000: add back
subsystem_device check")
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: <stable@vger.kernel.org> # 3.7+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>