1 files changed, 57 insertions, 8 deletions

diff --git a/lib/lockref.c b/lib/lockref.c
index 9d76f404ce9a..f07a40d33871 100644
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -1,7 +1,16 @@
 #include <linux/export.h>
 #include <linux/lockref.h>
+#include <linux/mutex.h>
 
-#ifdef CONFIG_CMPXCHG_LOCKREF
+#if USE_CMPXCHG_LOCKREF
+
+/*
+ * Allow weakly-ordered memory architectures to provide barrier-less
+ * cmpxchg semantics for lockref updates.
+ */
+#ifndef cmpxchg64_relaxed
+# define cmpxchg64_relaxed cmpxchg64
+#endif
 
 /*
  * Note that the "cmpxchg()" reloads the "old" value for the
@@ -14,12 +23,13 @@
 	while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) {  	\
 		struct lockref new = old, prev = old;				\
 		CODE								\
-		old.lock_count = cmpxchg(&lockref->lock_count,			\
-					 old.lock_count, new.lock_count);	\
+		old.lock_count = cmpxchg64_relaxed(&lockref->lock_count,	\
+						   old.lock_count,		\
+						   new.lock_count);		\
 		if (likely(old.lock_count == prev.lock_count)) {		\
 			SUCCESS;						\
 		}								\
-		cpu_relax();							\
+		arch_mutex_cpu_relax();						\
 	}									\
 } while (0)
 
@@ -31,7 +41,7 @@
 
 /**
  * lockref_get - Increments reference count unconditionally
- * @lockcnt: pointer to lockref structure
+ * @lockref: pointer to lockref structure
  *
  * This operation is only valid if you already hold a reference
  * to the object, so you know the count cannot be zero.
@@ -52,7 +62,7 @@ EXPORT_SYMBOL(lockref_get);
 
 /**
  * lockref_get_not_zero - Increments count unless the count is 0
- * @lockcnt: pointer to lockref structure
+ * @lockref: pointer to lockref structure
  * Return: 1 if count updated successfully or 0 if count was zero
  */
 int lockref_get_not_zero(struct lockref *lockref)
@@ -80,7 +90,7 @@ EXPORT_SYMBOL(lockref_get_not_zero);
 
 /**
  * lockref_get_or_lock - Increments count unless the count is 0
- * @lockcnt: pointer to lockref structure
+ * @lockref: pointer to lockref structure
  * Return: 1 if count updated successfully or 0 if count was zero
  * and we got the lock instead.
  */
@@ -105,7 +115,7 @@ EXPORT_SYMBOL(lockref_get_or_lock);
 
 /**
  * lockref_put_or_lock - decrements count unless count <= 1 before decrement
- * @lockcnt: pointer to lockref structure
+ * @lockref: pointer to lockref structure
  * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
  */
 int lockref_put_or_lock(struct lockref *lockref)
@@ -126,3 +136,42 @@ int lockref_put_or_lock(struct lockref *lockref)
 	return 1;
 }
 EXPORT_SYMBOL(lockref_put_or_lock);
+
+/**
+ * lockref_mark_dead - mark lockref dead
+ * @lockref: pointer to lockref structure
+ */
+void lockref_mark_dead(struct lockref *lockref)
+{
+	assert_spin_locked(&lockref->lock);
+	lockref->count = -128;
+}
+EXPORT_SYMBOL(lockref_mark_dead);
+
+/**
+ * lockref_get_not_dead - Increments count unless the ref is dead
+ * @lockref: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if lockref was dead
+ */
+int lockref_get_not_dead(struct lockref *lockref)
+{
+	int retval;
+
+	CMPXCHG_LOOP(
+		new.count++;
+		if ((int)old.count < 0)
+			return 0;
+	,
+		return 1;
+	);
+
+	spin_lock(&lockref->lock);
+	retval = 0;
+	if ((int) lockref->count >= 0) {
+		lockref->count++;
+		retval = 1;
+	}
+	spin_unlock(&lockref->lock);
+	return retval;
+}
+EXPORT_SYMBOL(lockref_get_not_dead);