Merge branch 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj...

[karo-tx-linux.git] / include / linux / percpu-refcount.h

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 0afb48fd449d3f952afdfd64c170715cb90f6a08..5d8920e23073d8caff4ebe834eaab219e53dba0f 100644 (file)
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -121,6 +121,36 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
  * percpu_ref_tryget - try to increment a percpu refcount
  * @ref: percpu_ref to try-get
  *
+ * Increment a percpu refcount unless its count already reached zero.
+ * Returns %true on success; %false on failure.
+ *
+ * The caller is responsible for ensuring that @ref stays accessible.
+ */
+static inline bool percpu_ref_tryget(struct percpu_ref *ref)
+{
+       unsigned __percpu *pcpu_count;
+       int ret = false;
+
+       rcu_read_lock_sched();
+
+       pcpu_count = ACCESS_ONCE(ref->pcpu_count);
+
+       if (likely(REF_STATUS(pcpu_count) == PCPU_REF_PTR)) {
+               this_cpu_inc(*pcpu_count);
+               ret = true;
+       } else {
+               ret = atomic_inc_not_zero(&ref->count);
+       }
+
+       rcu_read_unlock_sched();
+
+       return ret;
+}
+
+/**
+ * percpu_ref_tryget_live - try to increment a live percpu refcount
+ * @ref: percpu_ref to try-get
+ *
  * Increment a percpu refcount unless it has already been killed.  Returns
  * %true on success; %false on failure.
  *
@@ -128,8 +158,10 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
  * will fail.  For such guarantee, percpu_ref_kill_and_confirm() should be
  * used.  After the confirm_kill callback is invoked, it's guaranteed that
  * no new reference will be given out by percpu_ref_tryget().
+ *
+ * The caller is responsible for ensuring that @ref stays accessible.
  */
-static inline bool percpu_ref_tryget(struct percpu_ref *ref)
+static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
 {
        unsigned __percpu *pcpu_count;
        int ret = false;