On Tue, Jan 24, 2012 at 01:33:37PM -0500, Alan Stern wrote: > Greg: > > This patch series removes the get_driver() and put_driver() routines > from the kernel. > > Those routines don't do anything useful. Their comments say that they > increment and decrement the driver's reference count, just like > get_device()/put_device() and a lot of other utility routines. But a > struct driver is _not_ like a struct device! It resembles a piece of > code more than a piece of data -- it acts as an encapsulation of a > driver. Incrementing its refcount doesn't have much meaning because a > driver's lifetime isn't determined by the structure's refcount; it's > determined by when the driver's module gets unloaded. > > What really matters for a driver is whether or not it is registered. > Drivers expect, for example, that none of their methods will be called > after driver_unregister() returns. It doesn't matter if some other > thread still holds a reference to the driver structure; that reference > mustn't be used for accessing the driver code after unregistration. > get_driver() does not do any checking for this. > > People may have been misled by the kerneldoc into thinking that the > references obtained by get_driver() do somehow pin the driver structure > in memory. This simply isn't true; all it pins is the associated > private structure. Code that needs to pin a driver must do it some > other way (probably by calling try_module_get()). > > In short, these routines don't do anything useful and they can actively > mislead people. Removing them won't introduce any bugs that aren't > already present. There is no reason to keep them. Very nice work, all now applied, thanks for doing this. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
