Re: [PATCH] iio: Simplify IIO provider access locking mechanism

[Lars-Peter Clausen]

On 01/09/2015 05:14 PM, Ivan T. Ivanov wrote:
> On Fri, 2015-01-09 at 16:54 +0100, Lars-Peter Clausen wrote:
> > On 01/09/2015 04:50 PM, Ivan T. Ivanov wrote:
> > > On Fri, 2015-01-09 at 16:41 +0100, Lars-Peter Clausen wrote:
> > > > On 01/09/2015 04:38 PM, Ivan T. Ivanov wrote:
> > > > > Instead of checking whether provider module is still
> > > > > loaded on every access to device just lock module to
> > > > > memory when client get reference to provider device.
> > > >
> > > > This has nothing to do with the module, it's about the device. In the Linux
> > > > device driver model as device can be unbound at any time and the IIO
> > > > framework needs to handle this.
> > >
> > > Hm. Probably i am missing something here, but is this
> > > still true if we have reference to device structure?
> >
> > Yes, that only prevents the memory of device from being freed. But the
> > device can still be unbound from the driver.
> >
> > Think of e.g. a USB device that is pulled from the USB connector. Nothing
> > you can do in software about having the device disappear.
>
> Agree, but I think that the patch is still valid. Module
> have to be pinned in memory as long as there are device
> driver users.

No, the idea of the Linux driver model is that you can remove the module of 
a driver at any time, which will unbind the device from the driver. Once you 
reinsert the module the device will be re-bound to the driver.

- Lars

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/