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Commit 37eca249 authored by Jayant Chowdhary's avatar Jayant Chowdhary
Browse files

Functions called by RequestThread::threadLoop must not hold mInterfaceMutex. 



Functions called by RequestThread::threadLoop must not hold
mInterfaceMutex since the following deadlock scenario may occur:

T1: disconnect() -> holds mInterfaceMutex and waits for RequestThread to
    exit
  T2: RequestThread::threadLoop()->reconfigureCamera (or any other function) that waits on
      mInterfaceMutex

leading to a deadlock

Bug: 143513518

Test: GCA
Test: CTS

Change-Id: I4bd856e5263934a54cd7087a01d35cfe10936196
Signed-off-by: default avatarJayant Chowdhary <jchowdhary@google.com>
parent 3066e206

services/camera/libcameraservice/device3/Camera3Device.cpp

+9 −2
Original line number Diff line number Diff line
@@ -2165,7 +2165,9 @@ void Camera3Device::internalUpdateStatusLocked(Status status) { 
}



void Camera3Device::pauseStateNotify(bool enable) {

    Mutex::Autolock il(mInterfaceLock);

    // We must not hold mInterfaceLock here since this function is called from

    // RequestThread::threadLoop and holding mInterfaceLock could lead to

    // deadlocks (http://b/143513518)

    Mutex::Autolock l(mLock);



    mPauseStateNotify = enable;
@@ -2742,7 +2744,9 @@ bool Camera3Device::reconfigureCamera(const CameraMetadata& sessionParams) { 
    ATRACE_CALL();

    bool ret = false;



    Mutex::Autolock il(mInterfaceLock);

    // We must not hold mInterfaceLock here since this function is called from

    // RequestThread::threadLoop and holding mInterfaceLock could lead to

    // deadlocks (http://b/143513518)

    nsecs_t maxExpectedDuration = getExpectedInFlightDuration();



    Mutex::Autolock l(mLock);
@@ -5371,6 +5375,9 @@ bool Camera3Device::RequestThread::updateSessionParameters(const CameraMetadata& 
bool Camera3Device::RequestThread::threadLoop() {

    ATRACE_CALL();

    status_t res;

    // Any function called from threadLoop() must not hold mInterfaceLock since

    // it could lead to deadlocks (disconnect() -> hold mInterfaceMutex -> wait for request thread

    // to finish -> request thread waits on mInterfaceMutex) http://b/143513518



    // Handle paused state.

    if (waitIfPaused()) {