On Tue, Oct 03, 2017 at 07:14:59AM -0700, Tejun Heo wrote: > Hello, > > On Tue, Oct 03, 2017 at 10:04:03PM +0800, Ming Lei wrote: > > Block layer need to call this function after holding > > rcu lock in a real hot path, so introduce this helper. > > The patch description is too anemic. It doesn't even describe what > changes are being made, let alone justifying them. Sorry for Cc you, and this change is needed by the following patch: https://marc.info/?l=linux-scsi&m=150703956929333&w=2 Block layer need to call percpu_ref_tryget_live() with holding RCU read lock, given it is a hot I/O path, that is why I make this patch so that we can avoid nested RCU read lock and save a bit cost. -- Ming
