Commit d630dc4c authored by Tejun Heo's avatar Tejun Heo

percpu-refcount: one bit is enough for REF_STATUS

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: default avatarTejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
parent 55c6c814
...@@ -88,12 +88,10 @@ static inline void percpu_ref_kill(struct percpu_ref *ref) ...@@ -88,12 +88,10 @@ static inline void percpu_ref_kill(struct percpu_ref *ref)
return percpu_ref_kill_and_confirm(ref, NULL); 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_PTR 0
#define PCPU_REF_DEAD 1 #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 * percpu_ref_get - increment a percpu refcount
......
...@@ -96,7 +96,7 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) ...@@ -96,7 +96,7 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu)
/* Mask out PCPU_REF_DEAD */ /* Mask out PCPU_REF_DEAD */
pcpu_count = (unsigned __percpu *) pcpu_count = (unsigned __percpu *)
(((unsigned long) pcpu_count) & ~PCPU_STATUS_MASK); (((unsigned long) pcpu_count) & ~PCPU_REF_DEAD);
for_each_possible_cpu(cpu) for_each_possible_cpu(cpu)
count += *per_cpu_ptr(pcpu_count, cpu); count += *per_cpu_ptr(pcpu_count, cpu);
......
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