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@xxxxxxxxx>
---
drivers/staging/comedi/comedi_fops.c | 42 ++++++++++++++++++++++++++++++++++++
drivers/staging/comedi/comedidev.h | 2 ++
2 files changed, 44 insertions(+)
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 403324c..5e5ddbd 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -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)
{
diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
index 08652df..a9b1468 100644
--- a/drivers/staging/comedi/comedidev.h
+++ b/drivers/staging/comedi/comedidev.h
@@ -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);
--
1.8.4.2
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