Greg KH wrote:

quoted text
>> The problem is not the device to talk to CUSE (/dev/cuse as in

>> /dev/fuse), for which module refcount and device refcount match fine.

>> But the whole point of CUSE is allowing CUSE clients to create arbitrary

>> character devices, so in addition to /dev/cuse which clients use to talk

>> to CUSE, CUSE hosts character devices for its clients and they come and

>> go dynamically and thus requires proper lifetime management.

>

> That's fine, it's just like a USB device that uses a cdev, right?  Or a

> PCI device, or any other type of device that can come and go independant

> of the cdev or module lifespan.

>

> So, you tie the cdev lifespan to the module lifespan with the

> MODULE_OWNER in the file operations.  As the cuse.ko module will own the

> cdev, it can handle that reference, and it can not be removed as long as

> userspace has the cdev open, right?

>

> It really isn't any different from any other type of removable device

> (i.e. any type of device...)

Ah.. right, but taking cdev refcount out of the picture requires adding

'severing' operation on cdev f_ops, which certainly is doable but isn't

it just cleaner to make cdev follow the usual lifetime management rules?

 An object which is referenced counted requires ->release if it's gonna

be used in any non-simplistic way.
Thanks.
--

tejun

--

unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in

the body of a message to majordomo@vger.kernel.org

More majordomo info at  http://vger.kernel.org/majordomo-info.html

Please read the FAQ at  http://www.tux.org/lkml/