cameraserver: Avoiding deadlocks while calling isPublicallyHiddenSecureCamera().
The following scenario can occur:
T1 serving Client A's disconnect() call:
T2 : serving Client B's connect() call
T2 : CameraProviderManager::openSession() locks mInterfaceMutex and waits on open() HAL
interface call
T1: updateStatus() locks mStatusListenerMutex
T1: CameraProviderManager::isPublicallyHiddenSecureCamera() waits
on mInterfaceMutex
T2: while waiting on open(), gets a torchModeStatus() callback from the camera HAL
T2: onStatusChanged()
T2: broadcastTorchModeStatus() which waits on mStatusListenerMutex
As a result there's a possible circular hold and wait between T1 and T2.
We cache isPublicallyHiddenSecureCamera in CameraState. That doesn't completely
avoid having to hold mInterfaceLock while calling isPublicallyHiddenSecureCamera() in CameraService
(cache updates), instead it reduces it. We instead need to hold mCameraStates lock which has a
smaller scope.
Bug: 141756275
Test: CTS
Test: GCA (sanity)
Merged-In: I4a697c1eaccc3603007be4a595febea981fbeb64
Change-Id: Ie5508afb126a874f76fbbfc2dd19ef79ae6255e0
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>
diff --git a/services/camera/libcameraservice/CameraService.cpp b/services/camera/libcameraservice/CameraService.cpp
index e663485..bdeb273 100644
--- a/services/camera/libcameraservice/CameraService.cpp
+++ b/services/camera/libcameraservice/CameraService.cpp
@@ -253,6 +253,15 @@
enumerateProviders();
}
+bool CameraService::isPublicallyHiddenSecureCamera(const String8& cameraId) {
+ auto state = getCameraState(cameraId);
+ if (state != nullptr) {
+ return state->isPublicallyHiddenSecureCamera();
+ }
+ // Hidden physical camera ids won't have CameraState
+ return mCameraProviderManager->isPublicallyHiddenSecureCamera(cameraId.c_str());
+}
+
void CameraService::updateCameraNumAndIds() {
Mutex::Autolock l(mServiceLock);
mNumberOfCameras = mCameraProviderManager->getCameraCount();
@@ -268,6 +277,8 @@
ALOGE("Failed to query device resource cost: %s (%d)", strerror(-res), res);
return;
}
+ bool isPublicallyHiddenSecureCamera =
+ mCameraProviderManager->isPublicallyHiddenSecureCamera(id.string());
std::set<String8> conflicting;
for (size_t i = 0; i < cost.conflictingDevices.size(); i++) {
conflicting.emplace(String8(cost.conflictingDevices[i].c_str()));
@@ -276,7 +287,8 @@
{
Mutex::Autolock lock(mCameraStatesLock);
mCameraStates.emplace(id, std::make_shared<CameraState>(id, cost.resourceCost,
- conflicting));
+ conflicting,
+ isPublicallyHiddenSecureCamera));
}
if (mFlashlight->hasFlashUnit(id)) {
@@ -514,8 +526,16 @@
"Camera subsystem is not available");;
}
- Status ret{};
+ if (shouldRejectHiddenCameraConnection(String8(cameraId))) {
+ ALOGW("Attempting to retrieve characteristics for system-only camera id %s, rejected",
+ String8(cameraId).string());
+ return STATUS_ERROR_FMT(ERROR_DISCONNECTED,
+ "No camera device with ID \"%s\" currently available",
+ String8(cameraId).string());
+ }
+
+ Status ret{};
status_t res = mCameraProviderManager->getCameraCharacteristics(
String8(cameraId).string(), cameraInfo);
if (res != OK) {
@@ -1330,7 +1350,7 @@
// publically hidden, we should reject the connection.
if (!hardware::IPCThreadState::self()->isServingCall() &&
CameraThreadState::getCallingPid() != getpid() &&
- mCameraProviderManager->isPublicallyHiddenSecureCamera(cameraId.c_str())) {
+ isPublicallyHiddenSecureCamera(cameraId)) {
return true;
}
return false;
@@ -1799,16 +1819,25 @@
{
Mutex::Autolock lock(mCameraStatesLock);
for (auto& i : mCameraStates) {
- if (!isVendorListener &&
- mCameraProviderManager->isPublicallyHiddenSecureCamera(i.first.c_str())) {
- ALOGV("Cannot add public listener for hidden system-only %s for pid %d",
- i.first.c_str(), CameraThreadState::getCallingPid());
- continue;
- }
cameraStatuses->emplace_back(i.first, mapToInterface(i.second->getStatus()));
}
}
+ // Remove the camera statuses that should be hidden from the client, we do
+ // this after collecting the states in order to avoid holding
+ // mCameraStatesLock and mInterfaceLock (held in
+ // isPublicallyHiddenSecureCamera()) at the same time.
+ cameraStatuses->erase(std::remove_if(cameraStatuses->begin(), cameraStatuses->end(),
+ [this, &isVendorListener](const hardware::CameraStatus& s) {
+ bool ret = !isVendorListener && isPublicallyHiddenSecureCamera(s.cameraId);
+ if (ret) {
+ ALOGV("Cannot add public listener for hidden system-only %s for pid %d",
+ s.cameraId.c_str(), CameraThreadState::getCallingPid());
+ }
+ return ret;
+ }),
+ cameraStatuses->end());
+
/*
* Immediately signal current torch status to this listener only
* This may be a subset of all the devices, so don't include it in the response directly
@@ -2870,8 +2899,9 @@
// ----------------------------------------------------------------------------
CameraService::CameraState::CameraState(const String8& id, int cost,
- const std::set<String8>& conflicting) : mId(id),
- mStatus(StatusInternal::NOT_PRESENT), mCost(cost), mConflicting(conflicting) {}
+ const std::set<String8>& conflicting, bool isHidden) : mId(id),
+ mStatus(StatusInternal::NOT_PRESENT), mCost(cost), mConflicting(conflicting),
+ mIsPublicallyHiddenSecureCamera(isHidden) {}
CameraService::CameraState::~CameraState() {}
@@ -2900,6 +2930,10 @@
return mId;
}
+bool CameraService::CameraState::isPublicallyHiddenSecureCamera() const {
+ return mIsPublicallyHiddenSecureCamera;
+}
+
// ----------------------------------------------------------------------------
// ClientEventListener
// ----------------------------------------------------------------------------
@@ -3235,10 +3269,10 @@
cameraId.string());
return;
}
-
+ bool isHidden = isPublicallyHiddenSecureCamera(cameraId);
// Update the status for this camera state, then send the onStatusChangedCallbacks to each
// of the listeners with both the mStatusStatus and mStatusListenerLock held
- state->updateStatus(status, cameraId, rejectSourceStates, [this]
+ state->updateStatus(status, cameraId, rejectSourceStates, [this,&isHidden]
(const String8& cameraId, StatusInternal status) {
if (status != StatusInternal::ENUMERATING) {
@@ -3260,8 +3294,7 @@
Mutex::Autolock lock(mStatusListenerLock);
for (auto& listener : mListenerList) {
- if (!listener.first &&
- mCameraProviderManager->isPublicallyHiddenSecureCamera(cameraId.c_str())) {
+ if (!listener.first && isHidden) {
ALOGV("Skipping camera discovery callback for system-only camera %s",
cameraId.c_str());
continue;