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| author | Tejun Heo <tj@kernel.org> | 2014-06-28 16:10:14 +0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-06-28 16:10:14 +0400 |
| commit | 9a1049da9bd2cd83fe11d46433e603c193aa9c71 (patch) | |
| tree | 007d2843abf0f064c294659334e69e297ffc2b74 /include/linux/percpu-refcount.h | |
| parent | 7d742075120deb831c7b94c268ca20d409e91d60 (diff) | |
| download | linux-9a1049da9bd2cd83fe11d46433e603c193aa9c71.tar.xz | |
percpu-refcount: require percpu_ref to be exited explicitly
Currently, a percpu_ref undoes percpu_ref_init() automatically by
freeing the allocated percpu area when the percpu_ref is killed.
While seemingly convenient, this has the following niggles.
* It's impossible to re-init a released reference counter without
going through re-allocation.
* In the similar vein, it's impossible to initialize a percpu_ref
count with static percpu variables.
* We need and have an explicit destructor anyway for failure paths -
percpu_ref_cancel_init().
This patch removes the automatic percpu counter freeing in
percpu_ref_kill_rcu() and repurposes percpu_ref_cancel_init() into a
generic destructor now named percpu_ref_exit(). percpu_ref_destroy()
is considered but it gets confusing with percpu_ref_kill() while
"exit" clearly indicates that it's the counterpart of
percpu_ref_init().
All percpu_ref_cancel_init() users are updated to invoke
percpu_ref_exit() instead and explicit percpu_ref_exit() calls are
added to the destruction path of all percpu_ref users.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Nicholas A. Bellinger <nab@linux-iscsi.org>
Cc: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'include/linux/percpu-refcount.h')
| -rw-r--r-- | include/linux/percpu-refcount.h | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index 6f8cd4c0546c..0ddd2839ca84 100644 --- a/include/linux/percpu-refcount.h +++ b/include/linux/percpu-refcount.h @@ -57,9 +57,7 @@ struct percpu_ref { atomic_t count; /* * The low bit of the pointer indicates whether the ref is in percpu - * mode; if set, then get/put will manipulate the atomic_t (this is a - * hack because we need to keep the pointer around for - * percpu_ref_kill_rcu()) + * mode; if set, then get/put will manipulate the atomic_t. */ unsigned long pcpu_count_ptr; percpu_ref_func_t *release; @@ -69,7 +67,7 @@ struct percpu_ref { int __must_check percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release); -void percpu_ref_cancel_init(struct percpu_ref *ref); +void percpu_ref_exit(struct percpu_ref *ref); void percpu_ref_kill_and_confirm(struct percpu_ref *ref, percpu_ref_func_t *confirm_kill); |