percpu-refcount currently reserves two lowest bits of its percpu
pointer to indicate its state; however, only one bit is used for
PCPU_REF_DEAD.
Simplify it by removing PCPU_STATUS_BITS/MASK and testing
PCPU_REF_DEAD directly. This also allows the compiler to choose a
more efficient instruction depending on the architecture.
Signed-off-by: Tejun Heo <t...@kernel.org>
Cc: Kent Overstreet <k...@daterainc.com>
Cc: Christoph Lameter <c...@linux-foundation.org>
---
include/linux/percpu-refcount.h | 4 +---
lib/percpu-refcount.c | 2 +-
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 5d8920e..bfdeb0d4 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -88,12 +88,10 @@ static inline void percpu_ref_kill(struct percpu_ref *ref)
return percpu_ref_kill_and_confirm(ref, NULL);
}
-#define PCPU_STATUS_BITS 2
-#define PCPU_STATUS_MASK ((1 << PCPU_STATUS_BITS) - 1)
#define PCPU_REF_PTR 0
#define PCPU_REF_DEAD 1
-#define REF_STATUS(count) (((unsigned long) count) & PCPU_STATUS_MASK)
+#define REF_STATUS(count) (((unsigned long) count) & PCPU_REF_DEAD)
/**
* percpu_ref_get - increment a percpu refcount
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index 963b703..17bce2b 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -96,7 +96,7 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu)
/* Mask out PCPU_REF_DEAD */
pcpu_count = (unsigned __percpu *)
- (((unsigned long) pcpu_count) & ~PCPU_STATUS_MASK);
+ (((unsigned long) pcpu_count) & ~PCPU_REF_DEAD);
for_each_possible_cpu(cpu)
count += *per_cpu_ptr(pcpu_count, cpu);
--
1.9.3
--
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