1 files changed, 12 insertions, 3 deletions

diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c
index 5fc1e2caa544..61959627e1e1 100644
--- a/arch/x86/lib/atomic64_32.c
+++ b/arch/x86/lib/atomic64_32.c
@@ -76,13 +76,22 @@ u64 atomic64_read(atomic64_t *ptr)
  */
 u64 atomic64_add_return(u64 delta, atomic64_t *ptr)
 {
-        u64 old_val, new_val;
+        /*
+         * Try first with a (probably incorrect) assumption about
+         * what we have there. We'll do two loops most likely,
+         * but we'll get an ownership MESI transaction straight away
+         * instead of a read transaction followed by a
+         * flush-for-ownership transaction:
+         */
+        u64 old_val, new_val, real_val = 1ULL << 32;
 
         do {
-                old_val = atomic_read(ptr);
+                old_val = real_val;
                 new_val = old_val + delta;
 
-        } while (atomic64_cmpxchg(ptr, old_val, new_val) != old_val);
+                real_val = atomic64_cmpxchg(ptr, old_val, new_val);
+
+        } while (real_val != old_val);
 
         return new_val;
 }