commit c0fdb98b87bdd88c643a630e18838ddcdd5ab964
author Eino-Ville Talvala <etalvala@google.com> Wed Oct 17 16:32:34 2012 -0700
committer Eino-Ville Talvala <etalvala@google.com> Wed Oct 17 19:00:06 2012 -0700
tree 2eaa9a079d75866f1dc771d7dbce67820c6159be
parent 509c451f99dff4bda6d73e301df43a5b95c4ffcb

Camera2: Fix potential deadlock

setPreviewWindow was holding a lock during long-lasting HAL calls
which may cause deadlock if the HAL calls back into the service during
the call. Stop holding the lock during these calls, since it's not
essential to do so.

Bug: 7320517
Change-Id: I4a35703d751e22ac32979b5a1288e291610576e7

services/camera/libcameraservice/Camera2Client.cpp

diff --git a/services/camera/libcameraservice/Camera2Client.cpp b/services/camera/libcameraservice/Camera2Client.cpp
index 98332f9..0675400 100644
--- a/services/camera/libcameraservice/Camera2Client.cpp
+++ b/services/camera/libcameraservice/Camera2Client.cpp
@@ -529,15 +529,19 @@
         return NO_ERROR;
     }
 
-    SharedParameters::Lock l(mParameters);
-    switch (l.mParameters.state) {
+    Parameters::State state;
+    {
+        SharedParameters::Lock l(mParameters);
+        state = l.mParameters.state;
+    }
+    switch (state) {
         case Parameters::DISCONNECTED:
         case Parameters::RECORD:
         case Parameters::STILL_CAPTURE:
         case Parameters::VIDEO_SNAPSHOT:
             ALOGE("%s: Camera %d: Cannot set preview display while in state %s",
                     __FUNCTION__, mCameraId,
-                    Parameters::getStateName(l.mParameters.state));
+                    Parameters::getStateName(state));
             return INVALID_OPERATION;
         case Parameters::STOPPED:
         case Parameters::WAITING_FOR_PREVIEW_WINDOW:
@@ -545,10 +549,8 @@
             break;
         case Parameters::PREVIEW:
             // Already running preview - need to stop and create a new stream
-            // TODO: Optimize this so that we don't wait for old stream to drain
-            // before spinning up new stream
             mStreamingProcessor->stopStream();
-            l.mParameters.state = Parameters::WAITING_FOR_PREVIEW_WINDOW;
+            state = Parameters::WAITING_FOR_PREVIEW_WINDOW;
             break;
     }
 
@@ -560,7 +562,9 @@
         return res;
     }
 
-    if (l.mParameters.state == Parameters::WAITING_FOR_PREVIEW_WINDOW) {
+    if (state == Parameters::WAITING_FOR_PREVIEW_WINDOW) {
+        SharedParameters::Lock l(mParameters);
+        l.mParameters.state = state;
         return startPreviewL(l.mParameters, false);
     }