Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5b13ed94 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

staging: comedi: add a kref to comedi device 



Add a `struct kref refcount` member to `struct comedi_device` to allow
safe destruction of the comedi device.  Only free the comedi device via
the 'release' callback `kref_put()`.  Currently, nothing calls
`kref_put()`, so the safe destruction is ineffective, but this will be
addressed by later patches.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 45c2bc55

drivers/staging/comedi/comedi_fops.c

+19 −3
Original line number Diff line number Diff line
@@ -89,12 +89,29 @@ static struct cdev comedi_cdev; 


static void comedi_device_init(struct comedi_device *dev)

{

	kref_init(&dev->refcount);

	spin_lock_init(&dev->spinlock);

	mutex_init(&dev->mutex);

	init_rwsem(&dev->attach_lock);

	dev->minor = -1;

}



static void comedi_dev_kref_release(struct kref *kref)

{

	struct comedi_device *dev =

		container_of(kref, struct comedi_device, refcount);



	mutex_destroy(&dev->mutex);

	kfree(dev);

}



int comedi_dev_put(struct comedi_device *dev)

{

	if (dev)

		return kref_put(&dev->refcount, comedi_dev_kref_release);

	return 1;

}



static void comedi_device_cleanup(struct comedi_device *dev)

{

	struct module *driver_module = NULL;
@@ -112,7 +129,6 @@ static void comedi_device_cleanup(struct comedi_device *dev) 
		dev->use_count--;

	}

	mutex_unlock(&dev->mutex);

	mutex_destroy(&dev->mutex);

}



static bool comedi_clear_board_dev(struct comedi_device *dev)
@@ -148,7 +164,7 @@ static void comedi_free_board_dev(struct comedi_device *dev) 
				       MKDEV(COMEDI_MAJOR, dev->minor));

		}

		comedi_device_cleanup(dev);

		kfree(dev);

		comedi_dev_put(dev);

	}

}
@@ -2494,7 +2510,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device) 
	if (i == COMEDI_NUM_BOARD_MINORS) {

		mutex_unlock(&dev->mutex);

		comedi_device_cleanup(dev);

		kfree(dev);

		comedi_dev_put(dev);

		pr_err("comedi: error: ran out of minor numbers for board device files.\n");

		return ERR_PTR(-EBUSY);

	}

drivers/staging/comedi/comedidev.h

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/mutex.h>

#include <linux/spinlock_types.h>

#include <linux/rwsem.h>

#include <linux/kref.h>



#include "comedi.h"
@@ -187,6 +188,7 @@ struct comedi_device { 
	spinlock_t spinlock;

	struct mutex mutex;

	struct rw_semaphore attach_lock;

	struct kref refcount;



	int n_subdevices;

	struct comedi_subdevice *subdevices;