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staging: comedi: add comedi_dev_get_from_minor() 

Add function `struct comedi_device *comedi_dev_get_from_minor(unsigned
minor)`.  This behaves like the existing `comedi_dev_from_minor()`
except that it also increments the `struct kref refcount` member (via
new helper function `comedi_dev_get()`) to prevent it being freed.  If
it returns a valid pointer, the caller is responsible for calling
`comedi_dev_put()` to decrement the reference count.

Export `comedi_dev_get_from_minor()` and `comedi_dev_put()` as they will
be used by the "kcomedilib" module in addition to the "comedi" module
itself.

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 15:03:33 +00:00 committed by Greg Kroah-Hartman
parent 5b13ed94a7
commit b449c1cad7
2 changed files with 44 additions and 0 deletions
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42
drivers/staging/comedi/comedi_fops.c
View File

@ -111,6 +111,14 @@ int comedi_dev_put(struct comedi_device *dev)
return kref_put(&dev->refcount, comedi_dev_kref_release);
return 1;
}
EXPORT_SYMBOL_GPL(comedi_dev_put);
static struct comedi_device *comedi_dev_get(struct comedi_device *dev)
{
if (dev)
kref_get(&dev->refcount);
return dev;
}
static void comedi_device_cleanup(struct comedi_device *dev)
{
@ -209,6 +217,40 @@ struct comedi_device *comedi_dev_from_minor(unsigned minor)
}
EXPORT_SYMBOL_GPL(comedi_dev_from_minor);
static struct comedi_device *comedi_dev_get_from_board_minor(unsigned minor)
{
struct comedi_device *dev;
BUG_ON(minor >= COMEDI_NUM_BOARD_MINORS);
mutex_lock(&comedi_board_minor_table_lock);
dev = comedi_dev_get(comedi_board_minor_table[minor]);
mutex_unlock(&comedi_board_minor_table_lock);
return dev;
}
static struct comedi_device *comedi_dev_get_from_subdevice_minor(unsigned minor)
{
struct comedi_device *dev;
struct comedi_subdevice *s;
unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;
BUG_ON(i >= COMEDI_NUM_SUBDEVICE_MINORS);
mutex_lock(&comedi_subdevice_minor_table_lock);
s = comedi_subdevice_minor_table[i];
dev = comedi_dev_get(s ? s->device : NULL);
mutex_unlock(&comedi_subdevice_minor_table_lock);
return dev;
}
struct comedi_device *comedi_dev_get_from_minor(unsigned minor)
{
if (minor < COMEDI_NUM_BOARD_MINORS)
return comedi_dev_get_from_board_minor(minor);
else
return comedi_dev_get_from_subdevice_minor(minor);
}
EXPORT_SYMBOL_GPL(comedi_dev_get_from_minor);
static struct comedi_subdevice *
comedi_read_subdevice(const struct comedi_device *dev, unsigned int minor)
{

2
drivers/staging/comedi/comedidev.h
View File

@ -236,6 +236,8 @@ static const unsigned COMEDI_SUBDEVICE_MINOR_SHIFT = 4;
static const unsigned COMEDI_SUBDEVICE_MINOR_OFFSET = 1;
struct comedi_device *comedi_dev_from_minor(unsigned minor);
struct comedi_device *comedi_dev_get_from_minor(unsigned minor);
int comedi_dev_put(struct comedi_device *dev);
void init_polling(void);
void cleanup_polling(void);