Messages in this thread | | | Subject | Re: [PATCH 2/4] lib/percpu-refcount: introduce percpu_ref_resurge() | From | "jianchao.wang" <> | Date | Wed, 19 Sep 2018 13:19:10 +0800 |
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Hi Ming
On 09/18/2018 06:19 PM, Ming Lei wrote: > + unsigned long __percpu *percpu_count; > + > + WARN_ON_ONCE(__ref_is_percpu(ref, &percpu_count)); > + > + /* get one extra ref for avoiding race with .release */ > + rcu_read_lock_sched(); > + atomic_long_add(1, &ref->count); > + rcu_read_unlock_sched(); > + }
The rcu_read_lock_sched here is redundant. We have been in the critical section of a spin_lock_irqsave.
The atomic_long_add(1, &ref->count) may have two result. 1. ref->count > 1 it will not drop to zero any more. 2. ref->count == 1 it has dropped to zero and .release may be running.
Thanks Jianchao
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