commit 58aa9c1fa7397b3ca76ddffc5774a0637d42a822
author Emilian Peev <epeev@google.com> Tue May 24 18:23:10 2022 -0700
committer Emilian Peev <epeev@google.com> Wed May 25 01:34:20 2022 +0000
tree b37066257397632861dfa3563c43613ecffed2a9
parent a2ac684a282bf99b8d6846a5034b9aaa61fc0c2c

Camera: Avoid possible deadlock during R&C updates

Rotate and crop updates in the legacy shim layer are
synchronized via the 'mBinderSerializationLock'.
The binder thread that does this will also acquire
the camera service lock. However there might another
thread that is in the middle of a client disconnect
and already owns 'mBinderSerializationLock'. The second
thread will also try to acquire the camera service lock
as shown below and this can result in a deadlock.
Avoid this by using a dedicated lock for the rotate and
crop updates instead of 'mBinderSerializationLock'.

Thread 2:
android::CameraService::removeByClient
..
android::Camera2Client::disconnect()

Thread 1:
android::Camera2Client::setRotateAndCropOverride
android::CameraService::notifyDisplayConfigurationChange

Bug: 233752445
Test: Camera CTS
Change-Id: I3d37f0f6034e929a0bf3321ba122fffbd21fa923

services/camera/libcameraservice/api1/Camera2Client.cpp

diff --git a/services/camera/libcameraservice/api1/Camera2Client.cpp b/services/camera/libcameraservice/api1/Camera2Client.cpp
index a6a89af..c2f8488 100644
--- a/services/camera/libcameraservice/api1/Camera2Client.cpp
+++ b/services/camera/libcameraservice/api1/Camera2Client.cpp
@@ -1689,12 +1689,15 @@
                 __FUNCTION__, mCameraId, degrees);
         return BAD_VALUE;
     }
-    SharedParameters::Lock l(mParameters);
-    if (mRotateAndCropMode != ANDROID_SCALER_ROTATE_AND_CROP_NONE) {
-        ALOGI("%s: Rotate and crop set to: %d, skipping display orientation!", __FUNCTION__,
-                mRotateAndCropMode);
-        transform = mRotateAndCropPreviewTransform;
+    {
+        Mutex::Autolock icl(mRotateAndCropLock);
+        if (mRotateAndCropMode != ANDROID_SCALER_ROTATE_AND_CROP_NONE) {
+            ALOGI("%s: Rotate and crop set to: %d, skipping display orientation!", __FUNCTION__,
+                    mRotateAndCropMode);
+            transform = mRotateAndCropPreviewTransform;
+        }
     }
+    SharedParameters::Lock l(mParameters);
     if (transform != l.mParameters.previewTransform &&
             getPreviewStreamId() != NO_STREAM) {
         mDevice->setStreamTransform(getPreviewStreamId(), transform);
@@ -2317,7 +2320,7 @@
     if (rotateAndCrop > ANDROID_SCALER_ROTATE_AND_CROP_AUTO) return BAD_VALUE;
 
     {
-        Mutex::Autolock icl(mBinderSerializationLock);
+        Mutex::Autolock icl(mRotateAndCropLock);
         if (mRotateAndCropIsSupported) {
             mRotateAndCropMode = rotateAndCrop;
         } else {