Camera: Avoid recursive deadlock during device state changes
Device state change notifications are currently triggered while
holding 'mInterfaceMutex'. In case the camera provider tries
to add or remove a certain device/devices, then the provider
manager will try to recursively obtain the same 'mInterfaceMutex'.
Also avoid holding the 'mServiceLock' when notifying the
camera provider manager, access to its public interface
is already synchronized via 'mInterfaceMutex'.
Bug: 199240726
Test: Camera CTS
Change-Id: I9c71cc93ab91adc905488f954294b641d107de72
diff --git a/services/camera/libcameraservice/common/CameraProviderManager.cpp b/services/camera/libcameraservice/common/CameraProviderManager.cpp
index 4f2b878..556ddda 100644
--- a/services/camera/libcameraservice/common/CameraProviderManager.cpp
+++ b/services/camera/libcameraservice/common/CameraProviderManager.cpp
@@ -359,7 +359,13 @@
for (auto& provider : mProviders) {
ALOGV("%s: Notifying %s for new state 0x%" PRIx64,
__FUNCTION__, provider->mProviderName.c_str(), newState);
+ // b/199240726 Camera providers can for example try to add/remove
+ // camera devices as part of the state change notification. Holding
+ // 'mInterfaceMutex' while calling 'notifyDeviceStateChange' can
+ // result in a recursive deadlock.
+ mInterfaceMutex.unlock();
status_t singleRes = provider->notifyDeviceStateChange(mDeviceState);
+ mInterfaceMutex.lock();
if (singleRes != OK) {
ALOGE("%s: Unable to notify provider %s about device state change",
__FUNCTION__,
@@ -1185,10 +1191,12 @@
}
bool CameraProviderManager::isHiddenPhysicalCamera(const std::string& cameraId) const {
+ std::lock_guard<std::mutex> lock(mInterfaceMutex);
return isHiddenPhysicalCameraInternal(cameraId).first;
}
status_t CameraProviderManager::filterSmallJpegSizes(const std::string& cameraId) {
+ std::lock_guard<std::mutex> lock(mInterfaceMutex);
for (auto& provider : mProviders) {
for (auto& deviceInfo : provider->mDevices) {
if (deviceInfo->mId == cameraId) {