On Fri, Feb 16, 2018 at 05:39:27PM +0000, Quentin Perret wrote: > AFAIU it should be safe, but without your check you'll have to go through > cpus_read_lock()/unlock() every time a CPU is hotplugged. There is probably > no good reason to re-do that again and again if the state of the key > never changes. I don't know how expensive those lock/unlock operations are, > but I bet they are more expensive than testing static_branch_unlikely() :)
This is not a performance critical path, more obvious code is more better. Also cpus_read_lock() is dirt cheap most of the time.