1 files changed, 34 insertions, 12 deletions

diff --git a/third_party/libwebrtc/modules/video_capture/linux/video_capture_v4l2.cc b/third_party/libwebrtc/modules/video_capture/linux/video_capture_v4l2.cc
index 08d23f7f58..b6e7e79a2a 100644
--- a/third_party/libwebrtc/modules/video_capture/linux/video_capture_v4l2.cc
+++ b/third_party/libwebrtc/modules/video_capture/linux/video_capture_v4l2.cc
@@ -62,6 +62,7 @@ VideoCaptureModuleV4L2::VideoCaptureModuleV4L2()
       _deviceId(-1),
       _deviceFd(-1),
       _buffersAllocatedByDevice(-1),
+      _streaming(false),
       _captureStarted(false),
       _pool(NULL) {}
 
@@ -110,6 +111,7 @@ int32_t VideoCaptureModuleV4L2::Init(const char* deviceUniqueIdUTF8) {
 
 VideoCaptureModuleV4L2::~VideoCaptureModuleV4L2() {
   RTC_DCHECK_RUN_ON(&api_checker_);
+  RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
 
   StopCapture();
   if (_deviceFd != -1)
@@ -128,6 +130,14 @@ int32_t VideoCaptureModuleV4L2::StartCapture(
     }
   }
 
+  {
+  // We don't want members above to be guarded by capture_checker_ as
+  // it's meant to be for members that are accessed on the API thread
+  // only when we are not capturing. The code above can be called many
+  // times while sharing instance of VideoCaptureV4L2 between websites
+  // and therefore it would not follow the requirements of this checker.
+  RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
+
   // Set a baseline of configured parameters. It is updated here during
   // configuration, then read from the capture thread.
   configured_capability_ = capability;
@@ -289,18 +299,23 @@ int32_t VideoCaptureModuleV4L2::StartCapture(
 
   _requestedCapability = capability;
   _captureStarted = true;
+  _streaming = true;
 
   // start capture thread;
-  if (_captureThread.empty()) {
-    quit_ = false;
-    _captureThread = rtc::PlatformThread::SpawnJoinable(
-        [self = scoped_refptr(this)] {
-          while (self->CaptureProcess()) {
-          }
-        },
-        "CaptureThread",
-        rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kHigh));
+  if (!_captureThread.empty()) {
+    return 0;
+  }
+
+  quit_ = false;
   }
+
+  _captureThread = rtc::PlatformThread::SpawnJoinable(
+      [self = scoped_refptr(this)] {
+        while (self->CaptureProcess()) {
+        }
+      },
+      "CaptureThread",
+      rtc::ThreadAttributes().SetPriority(rtc::ThreadPriority::kHigh));
   return 0;
 }
 
@@ -316,9 +331,12 @@ int32_t VideoCaptureModuleV4L2::StopCapture() {
     _captureThread.Finalize();
   }
 
+  _captureStarted = false;
+
+  RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
   MutexLock lock(&capture_lock_);
-  if (_captureStarted) {
-    _captureStarted = false;
+  if (_streaming) {
+    _streaming = false;
 
     DeAllocateVideoBuffers();
     close(_deviceFd);
@@ -333,6 +351,7 @@ int32_t VideoCaptureModuleV4L2::StopCapture() {
 // critical section protected by the caller
 
 bool VideoCaptureModuleV4L2::AllocateVideoBuffers() {
+  RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
   struct v4l2_requestbuffers rbuffer;
   memset(&rbuffer, 0, sizeof(v4l2_requestbuffers));
 
@@ -383,6 +402,7 @@ bool VideoCaptureModuleV4L2::AllocateVideoBuffers() {
 }
 
 bool VideoCaptureModuleV4L2::DeAllocateVideoBuffers() {
+  RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
   // unmap buffers
   for (int i = 0; i < _buffersAllocatedByDevice; i++)
     munmap(_pool[i].start, _pool[i].length);
@@ -400,10 +420,12 @@ bool VideoCaptureModuleV4L2::DeAllocateVideoBuffers() {
 }
 
 bool VideoCaptureModuleV4L2::CaptureStarted() {
+  RTC_DCHECK_RUN_ON(&api_checker_);
   return _captureStarted;
 }
 
 bool VideoCaptureModuleV4L2::CaptureProcess() {
+  RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
 
   int retVal = 0;
   struct pollfd rSet;
@@ -432,7 +454,7 @@ bool VideoCaptureModuleV4L2::CaptureProcess() {
       return true;
     }
 
-    if (_captureStarted) {
+    if (_streaming) {
       struct v4l2_buffer buf;
       memset(&buf, 0, sizeof(struct v4l2_buffer));
       buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;