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

Commit bf11c134 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

staging: comedi: use attach_lock semaphore during attach and detach 



Acquire the `attach_lock` semaphore in the `struct comedi_device` while
modifying the `attached` flag.  This is a "write" acquire.  Note that
the main mutex in the `struct comedi_device` is also held at this time.
Tasks wishing to check the device is attached will need to either
acquire the main mutex, or "read" acquire the `attach_lock` semaphore,
or both in that order.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2f3fdcd7

drivers/staging/comedi/drivers.c

+4 −1
Original line number Diff line number Diff line
@@ -133,10 +133,12 @@ static void cleanup_device(struct comedi_device *dev) 


void comedi_device_detach(struct comedi_device *dev)

{

	down_write(&dev->attach_lock);

	dev->attached = false;

	if (dev->driver)

		dev->driver->detach(dev);

	cleanup_device(dev);

	up_write(&dev->attach_lock);

}



static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
@@ -355,8 +357,9 @@ static int comedi_device_postconfig(struct comedi_device *dev) 
	ret = __comedi_device_postconfig(dev);

	if (ret < 0)

		return ret;

	smp_wmb();

	down_write(&dev->attach_lock);

	dev->attached = true;

	up_write(&dev->attach_lock);

	return 0;

}