#ifdef CONFIG_CMPXCHG_LOCKREF
+/*
+ * Allow weakly-ordered memory architectures to provide barrier-less
+ * cmpxchg semantics for lockref updates.
+ */
+#ifndef cmpxchg64_relaxed
+# define cmpxchg64_relaxed cmpxchg64
+#endif
+
+/*
+ * Allow architectures to override the default cpu_relax() within CMPXCHG_LOOP.
+ * This is useful for architectures with an expensive cpu_relax().
+ */
+#ifndef arch_mutex_cpu_relax
+# define arch_mutex_cpu_relax() cpu_relax()
+#endif
+
/*
* Note that the "cmpxchg()" reloads the "old" value for the
* failure case.
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)
/**
* 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.
/**
* 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)
/**
* 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.
*/
/**
* 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)
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;
+}
+
+/**
+ * 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);