lockref: allow relaxed cmpxchg64 variant for lockless updates

[karo-tx-linux.git] / lib / lockref.c

diff --git a/lib/lockref.c b/lib/lockref.c
index 677d036cf3c70d6d72b9aa5f108470dd890752cd..e294ae445c9ab4b7e97dd1a46efc7dc7d6a1848d 100644 (file)
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -3,6 +3,14 @@
 
 #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
+
 /*
  * Note that the "cmpxchg()" reloads the "old" value for the
  * failure case.
@@ -14,8 +22,9 @@
        while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) {     \
                struct lockref new = old, prev = old;                           \
                CODE                                                            \
-               old.lock_count = cmpxchg64(&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;                                                \
                }                                                               \