camera2: Add camera client eviction enforcement.

- This updates the CameraService to implement client
  eviction behavior based on process priority.

Bug: 19186859

Change-Id: I646939b1cdf1a2237c4e5044164d55a2542cf36e

1 files changed, 15 insertions, 36 deletions

diff --git a/services/camera/libcameraservice/api1/CameraClient.cpp b/services/camera/libcameraservice/api1/CameraClient.cpp
index 6bea3b6..e552633 100644
--- a/services/camera/libcameraservice/api1/CameraClient.cpp
+++ b/services/camera/libcameraservice/api1/CameraClient.cpp
@@ -99,12 +99,7 @@ status_t CameraClient::initialize(CameraModule *module) {
 
 // tear down the client
 CameraClient::~CameraClient() {
-    // this lock should never be NULL
-    Mutex* lock = mCameraService->getClientLockById(mCameraId);
-    lock->lock();
     mDestructionStarted = true;
-    // client will not be accessed from callback. should unlock to prevent dead-lock in disconnect
-    lock->unlock();
     int callingPid = getCallingPid();
     LOG1("CameraClient::~CameraClient E (pid %d, this %p)", callingPid, this);
 
@@ -116,11 +111,11 @@ status_t CameraClient::dump(int fd, const Vector<String16>& args) {
     const size_t SIZE = 256;
     char buffer[SIZE];
 
-    size_t len = snprintf(buffer, SIZE, "Client[%d] (%p) PID: %d\n",
+    size_t len = snprintf(buffer, SIZE, "Client[%d] (%p) with UID %d\n",
             mCameraId,
             (getRemoteCallback() != NULL ?
                     IInterface::asBinder(getRemoteCallback()).get() : NULL),
-            mClientPid);
+            mClientUid);
     len = (len > SIZE - 1) ? SIZE - 1 : len;
     write(fd, buffer, len);
 
@@ -677,6 +672,13 @@ bool CameraClient::lockIfMessageWanted(int32_t msgType) {
                 LOG1("lockIfMessageWanted(%d): waited for %d ms",
                     msgType, sleepCount * CHECK_MESSAGE_INTERVAL);
             }
+
+            // If messages are no longer enabled after acquiring lock, release and drop message
+            if ((mMsgEnabled & msgType) == 0) {
+                mLock.unlock();
+                break;
+            }
+
             return true;
         }
         if (sleepCount++ == 0) {
@@ -702,26 +704,13 @@ bool CameraClient::lockIfMessageWanted(int32_t msgType) {
 //      (others)                        c->dataCallback
 // dataCallbackTimestamp
 //      (others)                        c->dataCallbackTimestamp
-//
-// NOTE: the *Callback functions grab mLock of the client before passing
-// control to handle* functions. So the handle* functions must release the
-// lock before calling the ICameraClient's callbacks, so those callbacks can
-// invoke methods in the Client class again (For example, the preview frame
-// callback may want to releaseRecordingFrame). The handle* functions must
-// release the lock after all accesses to member variables, so it must be
-// handled very carefully.
 
 void CameraClient::notifyCallback(int32_t msgType, int32_t ext1,
         int32_t ext2, void* user) {
     LOG2("notifyCallback(%d)", msgType);
 
-    Mutex* lock = getClientLockFromCookie(user);
-    if (lock == NULL) return;
-    Mutex::Autolock alock(*lock);
-
-    CameraClient* client =
-            static_cast<CameraClient*>(getClientFromCookie(user));
-    if (client == NULL) return;
+    sp<CameraClient> client = static_cast<CameraClient*>(getClientFromCookie(user).get());
+    if (client.get() == nullptr) return;
 
     if (!client->lockIfMessageWanted(msgType)) return;
 
@@ -740,13 +729,8 @@ void CameraClient::dataCallback(int32_t msgType,
         const sp<IMemory>& dataPtr, camera_frame_metadata_t *metadata, void* user) {
     LOG2("dataCallback(%d)", msgType);
 
-    Mutex* lock = getClientLockFromCookie(user);
-    if (lock == NULL) return;
-    Mutex::Autolock alock(*lock);
-
-    CameraClient* client =
-            static_cast<CameraClient*>(getClientFromCookie(user));
-    if (client == NULL) return;
+    sp<CameraClient> client = static_cast<CameraClient*>(getClientFromCookie(user).get());
+    if (client.get() == nullptr) return;
 
     if (!client->lockIfMessageWanted(msgType)) return;
     if (dataPtr == 0 && metadata == NULL) {
@@ -778,13 +762,8 @@ void CameraClient::dataCallbackTimestamp(nsecs_t timestamp,
         int32_t msgType, const sp<IMemory>& dataPtr, void* user) {
     LOG2("dataCallbackTimestamp(%d)", msgType);
 
-    Mutex* lock = getClientLockFromCookie(user);
-    if (lock == NULL) return;
-    Mutex::Autolock alock(*lock);
-
-    CameraClient* client =
-            static_cast<CameraClient*>(getClientFromCookie(user));
-    if (client == NULL) return;
+    sp<CameraClient> client = static_cast<CameraClient*>(getClientFromCookie(user).get());
+    if (client.get() == nullptr) return;
 
     if (!client->lockIfMessageWanted(msgType)) return;