On Tue, Sep 11, 2018 at 09:30:32AM -0700, Tejun Heo wrote: > On Wed, Sep 12, 2018 at 12:05:33AM +0800, Ming Lei wrote: > > On Tue, Sep 11, 2018 at 08:49:59AM -0700, Tejun Heo wrote: > > > On Tue, Sep 11, 2018 at 11:45:41PM +0800, Ming Lei wrote: > > > > > So, this part seems wrong. The function is called percpu_ref_reinit() > > > > > - the refcnt is expected to be in its initial state with just the base > > > > > ref once this function returns. If you're removing the restriction on > > > > > > > > But the comment says that 'Re-initialize @ref so that it's in the same > > > > state as when it finished', and this invariant isn't changed with this > > > > patch. > > > > > > The comment goes "when perpcu_ref_init() finished". The function is > > > called re _init_. It should put the ref in the initial state, right? > > > > OK, I am fine to keep the behaviour for this API, will introduce a new helper > > for NVMe. > > Why aren't switch_to_atomic/percpu enough? The blk-mq's use case is this _reinit is done on one refcount which was killed via percpu_ref_kill(), so the DEAD flag has to be cleared. > > > However, it is doable to switch to percpu mode from atomic mode when it > > doesn't drop to zero, looks like sort of perpcu_ref_reinit(inherit_old_refcount). > > Isn't that way more contorted than just switching operating modes? As explained above. Thanks, Ming
