On 04/10/2018 10:16 AM, David Miller wrote: > > The tradeoff here is that now you are doing two unnecessary atomic > operations per stats dump. > > That is what the RCU lock allows us to avoid. >
dev_hold() and dev_put() are actually per cpu increment and decrements, pretty cheap these days. Problem here is that any preemption of the process holding device reference might trigger warnings in device unregister.