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: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
2f3fdcd7ce
commit
bf11c13424
|
@ -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;
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue