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percpu_ref: release percpu memory early without PERCPU_REF_ALLOW_REINIT 

Release percpu memory after finishing the switch to the atomic mode
if only PERCPU_REF_ALLOW_REINIT isn't set.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
This commit is contained in:
Roman Gushchin 2019-05-07 10:01:50 -07:00 committed by Dennis Zhou
parent ddde2af747
commit 7d9ab9b6ad
2 changed files with 12 additions and 2 deletions
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1
include/linux/percpu-refcount.h
View File

@ -102,6 +102,7 @@ struct percpu_ref {
percpu_ref_func_t *release;
percpu_ref_func_t *confirm_switch;
bool force_atomic:1;
bool allow_reinit:1;
struct rcu_head rcu;
};

13
lib/percpu-refcount.c
View File

@ -69,11 +69,14 @@ int percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release,
return -ENOMEM;
ref->force_atomic = flags & PERCPU_REF_INIT_ATOMIC;
ref->allow_reinit = flags & PERCPU_REF_ALLOW_REINIT;
if (flags & (PERCPU_REF_INIT_ATOMIC | PERCPU_REF_INIT_DEAD))
if (flags & (PERCPU_REF_INIT_ATOMIC | PERCPU_REF_INIT_DEAD)) {
ref->percpu_count_ptr |= __PERCPU_REF_ATOMIC;
else
ref->allow_reinit = true;
} else {
start_count += PERCPU_COUNT_BIAS;
}
if (flags & PERCPU_REF_INIT_DEAD)
ref->percpu_count_ptr |= __PERCPU_REF_DEAD;
@ -119,6 +122,9 @@ static void percpu_ref_call_confirm_rcu(struct rcu_head *rcu)
ref->confirm_switch = NULL;
wake_up_all(&percpu_ref_switch_waitq);
if (!ref->allow_reinit)
percpu_ref_exit(ref);
/* drop ref from percpu_ref_switch_to_atomic() */
percpu_ref_put(ref);
}
@ -194,6 +200,9 @@ static void __percpu_ref_switch_to_percpu(struct percpu_ref *ref)
if (!(ref->percpu_count_ptr & __PERCPU_REF_ATOMIC))
return;
if (WARN_ON_ONCE(!ref->allow_reinit))
return;
atomic_long_add(PERCPU_COUNT_BIAS, &ref->count);
/*