diff --git a/services/core/java/com/android/server/vibrator/VibrationStepConductor.java b/services/core/java/com/android/server/vibrator/VibrationStepConductor.java
index 58407cf7fd461..e12426b2b02c6 100644
--- a/services/core/java/com/android/server/vibrator/VibrationStepConductor.java
+++ b/services/core/java/com/android/server/vibrator/VibrationStepConductor.java
@@ -60,8 +60,6 @@ final class VibrationStepConductor implements IBinder.DeathRecipient {
     static final float RAMP_OFF_AMPLITUDE_MIN = 1e-3f;
     static final List<Step> EMPTY_STEP_LIST = new ArrayList<>();
 
-    private final Object mLock = new Object();
-
     // Used within steps.
     public final VibrationSettings vibrationSettings;
     public final DeviceVibrationEffectAdapter deviceEffectAdapter;
@@ -74,6 +72,11 @@ final class VibrationStepConductor implements IBinder.DeathRecipient {
     private final Queue<Step> mPendingOnVibratorCompleteSteps = new LinkedList<>();
 
     // Signalling fields.
+    // Note that vibrator callback signals may happen inside vibrator HAL calls made by the
+    // VibrationThread, or on an external executor, so this lock should not be held for anything
+    // other than updating signalling state - particularly not during HAL calls or when invoking
+    // other callbacks that may trigger calls into the thread.
+    private final Object mLock = new Object();
     @GuardedBy("mLock")
     private final IntArray mSignalVibratorsComplete;
     @GuardedBy("mLock")
@@ -334,9 +337,9 @@ final class VibrationStepConductor implements IBinder.DeathRecipient {
      * The state update is recorded for processing on the main execution thread (VibrationThread).
      */
     public void notifyVibratorComplete(int vibratorId) {
-        if (Build.IS_DEBUGGABLE) {
-            expectIsVibrationThread(false);
-        }
+        // HAL callbacks may be triggered directly within HAL calls, so these notifications
+        // could be on the VibrationThread as it calls the HAL, or some other executor later.
+        // Therefore no thread assertion is made here.
 
         if (DEBUG) {
             Slog.d(TAG, "Vibration complete reported by vibrator " + vibratorId);
@@ -356,9 +359,9 @@ final class VibrationStepConductor implements IBinder.DeathRecipient {
      * (VibrationThread).
      */
     public void notifySyncedVibrationComplete() {
-        if (Build.IS_DEBUGGABLE) {
-            expectIsVibrationThread(false);
-        }
+        // HAL callbacks may be triggered directly within HAL calls, so these notifications
+        // could be on the VibrationThread as it calls the HAL, or some other executor later.
+        // Therefore no thread assertion is made here.
 
         if (DEBUG) {
             Slog.d(TAG, "Synced vibration complete reported by vibrator manager");
@@ -394,7 +397,7 @@ final class VibrationStepConductor implements IBinder.DeathRecipient {
         int[] vibratorsToProcess = null;
         boolean doCancel = false;
         boolean doCancelImmediate = false;
-        // Swap out the queue of completions to process.
+        // Collect signals to process, but don't keep the lock while processing them.
         synchronized (mLock) {
             if (mSignalCancelImmediate) {
                 if (mCancelledImmediately) {
@@ -407,6 +410,7 @@ final class VibrationStepConductor implements IBinder.DeathRecipient {
                 doCancel = true;
             }
             if (!doCancelImmediate && mSignalVibratorsComplete.size() > 0) {
+                // Swap out the queue of completions to process.
                 vibratorsToProcess = mSignalVibratorsComplete.toArray();  // makes a copy
                 mSignalVibratorsComplete.clear();
             }
diff --git a/services/core/java/com/android/server/vibrator/VibrationThread.java b/services/core/java/com/android/server/vibrator/VibrationThread.java
index 205ea62496ff3..cecc5c04dedcb 100644
--- a/services/core/java/com/android/server/vibrator/VibrationThread.java
+++ b/services/core/java/com/android/server/vibrator/VibrationThread.java
@@ -22,6 +22,7 @@ import android.os.IBinder;
 import android.os.PowerManager;
 import android.os.Process;
 import android.os.RemoteException;
+import android.os.SystemClock;
 import android.os.Trace;
 import android.os.WorkSource;
 import android.util.Slog;
@@ -176,7 +177,7 @@ final class VibrationThread extends Thread {
      * @return true if the vibration completed, or false if waiting timed out.
      */
     public boolean waitForThreadIdle(long maxWaitMillis) {
-        long now = System.currentTimeMillis();
+        long now = SystemClock.elapsedRealtime();
         long deadline = now + maxWaitMillis;
         synchronized (mLock) {
             while (true) {
@@ -191,7 +192,7 @@ final class VibrationThread extends Thread {
                 } catch (InterruptedException e) {
                     Slog.w(TAG, "VibrationThread interrupted waiting to stop, continuing");
                 }
-                now = System.currentTimeMillis();
+                now = SystemClock.elapsedRealtime();
             }
         }
     }