diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 49f74a2..dfba700 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -8747,9 +8747,11 @@
 
     while (!exitPending())
     {
-        Mutex::Autolock _l(mLock);
         Vector< sp<EffectChain> > effectChains;
 
+        { // under Thread lock
+        Mutex::Autolock _l(mLock);
+
         if (mSignalPending) {
             // A signal was raised while we were unlocked
             mSignalPending = false;
@@ -8784,10 +8786,13 @@
         updateMetadata_l();
 
         lockEffectChains_l(effectChains);
+        } // release Thread lock
+
         for (size_t i = 0; i < effectChains.size(); i ++) {
-            effectChains[i]->process_l();
+            effectChains[i]->process_l(); // Thread is not locked, but effect chain is locked
         }
-        // enable changes in effect chain
+
+        // enable changes in effect chain, including moving to another thread.
         unlockEffectChains(effectChains);
         // Effect chains will be actually deleted here if they were removed from
         // mEffectChains list during mixing or effects processing