LibThread: Remove redundant r/w of atomic variable in Lock::lock() (#3013)

m_holder.compare_exchange_strong(expected, desired, ...)
will either successfully update the value to desired if == expected
or put the current value in expected otherwise.

1 files changed, 2 insertions, 3 deletions

diff --git a/Libraries/LibThread/Lock.h b/Libraries/LibThread/Lock.h
index def18517ab..02c97a382f 100644
--- a/Libraries/LibThread/Lock.h
+++ b/Libraries/LibThread/Lock.h
@@ -72,12 +72,11 @@ ALWAYS_INLINE void Lock::lock()
     }
     for (;;) {
         int expected = 0;
-        if (m_holder.compare_exchange_strong(expected, tid, AK::memory_order_acq_rel)) {
-            m_holder = tid;
+        if (m_holder.compare_exchange_strong(expected, tid, AK::memory_order_acq_rel)) {            
             m_level = 1;
             return;
         }
-        donate(m_holder);
+        donate(expected);
     }
 }