From: Tejun Heo <tj@kernel.org>
Date: Tue, 6 Jan 2015 15:26:10 +0000 (-0500)
Subject: percpu_ref: implement percpu_ref_is_dying()
X-Git-Tag: v4.0-rc1~151^2
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4c907baf36d8339f393bb576d0bab29194d0e6ad;p=karo-tx-linux.git

percpu_ref: implement percpu_ref_is_dying()

Implement percpu_ref_is_dying() which tests whether the ref is dying
or dead.  This is useful to determine the current state when a
percpu_ref is used as a cyclic on/off switch via kill and reinit.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kmo@daterainc.com>
---

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 6a7a670366ab..12c9b485beb7 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -294,6 +294,20 @@ static inline void percpu_ref_put(struct percpu_ref *ref)
 	percpu_ref_put_many(ref, 1);
 }
 
+/**
+ * percpu_ref_is_dying - test whether a percpu refcount is dying or dead
+ * @ref: percpu_ref to test
+ *
+ * Returns %true if @ref is dying or dead.
+ *
+ * This function is safe to call as long as @ref is between init and exit
+ * and the caller is responsible for synchronizing against state changes.
+ */
+static inline bool percpu_ref_is_dying(struct percpu_ref *ref)
+{
+	return ref->percpu_count_ptr & __PERCPU_REF_DEAD;
+}
+
 /**
  * percpu_ref_is_zero - test whether a percpu refcount reached zero
  * @ref: percpu_ref to test