Add `comedi_open_from(path, from)` and `comedi_close_from(dev, from)` as
variants of the existing `comedi_from(path)` and `comedi_close(dev)`.
The additional `from` parameter is a minor device number that tells the
function that the COMEDI device is being opened or closed from another
COMEDI device if the value is in the range [0,
`COMEDI_NUM_BOARD_MINORS`-1]. In that case the function will refuse to
open the device if it would lead to a chain of devices opening each
other. (It will also impose a limit on the number of simultaneous opens
from one device to another because we need to count those.)
The new functions are intended to be used by the "comedi_bond" driver,
which is the only driver that uses the existing `comedi_open()` and
`comedi_close()` functions. The new functions will be used to avoid
some possible deadlock situations.
Replace the existing, exported `comedi_open()` and `comedi_close()`
functions with inline wrapper functions that call the newly exported
`comedi_open_from()` and `comedi_close_from()` functions.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20251027153748.4569-2-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move the main COMEDI driver headers out of "drivers/comedi/" into new
directory "include/linux/comedi/". These are "comedidev.h",
"comedilib.h", "comedi_pci.h", "comedi_pcmcia.h", and "comedi_usb.h".
Additionally, move the user-space API header "comedi.h" into
"include/uapi/linux/" and add "WITH Linux-syscall-note" to its
SPDX-License-Identifier.
Update the "COMEDI DRIVERS" section of the MAINTAINERS file to account
for these changes.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20211117120604.117740-2-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The comedi code came into the kernel back in 2008, but traces its
lifetime to much much earlier. It's been polished and buffed and
there's really nothing preventing it from being part of the "real"
portion of the kernel.
So move it to drivers/comedi/ as it belongs there.
Many thanks to the hundreds of developers who did the work to make this
happen.
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Link: https://lore.kernel.org/r/YHauop4u3sP6lz8j@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
