percpu: READ_ONCE() now implies smp_read_barrier_depends()

Because READ_ONCE() now implies smp_read_barrier_depends(), this commit
removes the now-redundant smp_read_barrier_depends() following the
READ_ONCE() in __ref_is_percpu().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 6658d9ee5257..864d167a1073 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -139,12 +139,12 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref,
          * when using it as a pointer, __PERCPU_REF_ATOMIC may be set in
          * between contaminating the pointer value, meaning that
          * READ_ONCE() is required when fetching it.
+         *
+         * The smp_read_barrier_depends() implied by READ_ONCE() pairs
+         * with smp_store_release() in __percpu_ref_switch_to_percpu().
          */
         percpu_ptr = READ_ONCE(ref->percpu_count_ptr);
 
-        /* paired with smp_store_release() in __percpu_ref_switch_to_percpu() */
-        smp_read_barrier_depends();
-
         /*
          * Theoretically, the following could test just ATOMIC; however,
          * then we'd have to mask off DEAD separately as DEAD may be