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| author | Tejun Heo <tj@kernel.org> | 2014-06-28 14:10:13 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-06-28 14:10:13 +0200 |
| commit | eae7975ddf031b3084f4a5f7d88f698aefad96fb (patch) | |
| tree | 5e5dd384eac28d12ac6ebcf197f92f543bd44c0d /lib/percpu-refcount.c | |
| parent | percpu-refcount: one bit is enough for REF_STATUS (diff) | |
| download | linux-eae7975ddf031b3084f4a5f7d88f698aefad96fb.tar.xz linux-eae7975ddf031b3084f4a5f7d88f698aefad96fb.zip | |
percpu-refcount: add helpers for ->percpu_count accesses
* All four percpu_ref_*() operations implemented in the header file
perform the same operation to determine whether the percpu_ref is
alive and extract the percpu pointer. Factor out the common logic
into __pcpu_ref_alive(). This doesn't change the generated code.
* There are a couple places in percpu-refcount.c which masks out
PCPU_REF_DEAD to obtain the percpu pointer. Factor it out into
pcpu_count_ptr().
* The above changes make the WARN_ON_ONCE() conditional at the top of
percpu_ref_kill_and_confirm() the only user of REF_STATUS(). Test
PCPU_REF_DEAD directly and remove REF_STATUS().
This patch doesn't introduce any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Diffstat (limited to 'lib/percpu-refcount.c')
| -rw-r--r-- | lib/percpu-refcount.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index 17bce2bccc14..087f1a04f9bc 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -31,6 +31,11 @@ #define PCPU_COUNT_BIAS (1U << 31) +static unsigned __percpu *pcpu_count_ptr(struct percpu_ref *ref) +{ + return (unsigned __percpu *)((unsigned long)ref->pcpu_count & ~PCPU_REF_DEAD); +} + /** * percpu_ref_init - initialize a percpu refcount * @ref: percpu_ref to initialize @@ -74,7 +79,7 @@ EXPORT_SYMBOL_GPL(percpu_ref_init); */ void percpu_ref_cancel_init(struct percpu_ref *ref) { - unsigned __percpu *pcpu_count = ref->pcpu_count; + unsigned __percpu *pcpu_count = pcpu_count_ptr(ref); int cpu; WARN_ON_ONCE(atomic_read(&ref->count) != 1 + PCPU_COUNT_BIAS); @@ -82,7 +87,7 @@ void percpu_ref_cancel_init(struct percpu_ref *ref) if (pcpu_count) { for_each_possible_cpu(cpu) WARN_ON_ONCE(*per_cpu_ptr(pcpu_count, cpu)); - free_percpu(ref->pcpu_count); + free_percpu(pcpu_count); } } EXPORT_SYMBOL_GPL(percpu_ref_cancel_init); @@ -90,14 +95,10 @@ EXPORT_SYMBOL_GPL(percpu_ref_cancel_init); static void percpu_ref_kill_rcu(struct rcu_head *rcu) { struct percpu_ref *ref = container_of(rcu, struct percpu_ref, rcu); - unsigned __percpu *pcpu_count = ref->pcpu_count; + unsigned __percpu *pcpu_count = pcpu_count_ptr(ref); unsigned count = 0; int cpu; - /* Mask out PCPU_REF_DEAD */ - pcpu_count = (unsigned __percpu *) - (((unsigned long) pcpu_count) & ~PCPU_REF_DEAD); - for_each_possible_cpu(cpu) count += *per_cpu_ptr(pcpu_count, cpu); @@ -152,7 +153,7 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) void percpu_ref_kill_and_confirm(struct percpu_ref *ref, percpu_ref_func_t *confirm_kill) { - WARN_ONCE(REF_STATUS(ref->pcpu_count) == PCPU_REF_DEAD, + WARN_ONCE((unsigned long)ref->pcpu_count & PCPU_REF_DEAD, "percpu_ref_kill() called more than once!\n"); ref->pcpu_count = (unsigned __percpu *) |