Commits
Tejun Heo committed a2f5630cb73
percpu_ref: remove unnecessary RCU grace period for staggered atomic switching confirmation At the beginning, percpu_ref guaranteed a RCU grace period between a call to percpu_ref_kill_and_confirm() and the invocation of the confirmation callback. This guarantee exposed internal implementation details and got rescinded while switching over to sched RCU; however, __percpu_ref_switch_to_atomic() still inserts a full sched RCU grace period even when it can simply wait for the previous attempt. Remove the unnecessary grace period and perform the confirmation synchronously for staggered atomic switching attempts. Update comments accordingly. Signed-off-by: Tejun Heo <tj@kernel.org>