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staging: comedi: add detachment counter for validity checks

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Add a member `detach_count` to `struct comedi_device` that is
incremented every time the device gets detached.  This will be used in
some validity checks in the 'read' and 'write' file operations to make
sure the attachment remains valid.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2013-11-08 15:03:29 +00:00 committed by Greg Kroah-Hartman
parent d19db51a0e
commit ef77c0b257
2 changed files with 2 additions and 0 deletions
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1
drivers/staging/comedi/comedidev.h
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@ -173,6 +173,7 @@ struct comedi_device {
struct device *class_dev;
int minor;
unsigned int detach_count;
/* hw_dev is passed to dma_alloc_coherent when allocating async buffers
* for subdevices that have async_dma_dir set to something other than
* DMA_NONE */

1
drivers/staging/comedi/drivers.c
View file

@ -136,6 +136,7 @@ void comedi_device_detach(struct comedi_device *dev)
comedi_device_cancel_all(dev);
down_write(&dev->attach_lock);
dev->attached = false;
dev->detach_count++;
if (dev->driver)
dev->driver->detach(dev);
comedi_device_detach_cleanup(dev);