libcamera: pipeline_handler: Make lock() and unlock() thread-safe

The PipelineHandler lock() and unlock() functions are documented as
thread-safe, but they're not. Fix them using a mutex.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
index fc6d476b..b473eb70 100644
--- a/include/libcamera/internal/pipeline_handler.h
+++ b/include/libcamera/internal/pipeline_handler.h
@@ -14,6 +14,7 @@
 #include <vector>
 
 #include <libcamera/base/object.h>
+#include <libcamera/base/thread.h>
 
 #include <libcamera/controls.h>
 #include <libcamera/stream.h>
@@ -73,6 +74,8 @@ protected:
 	CameraManager *manager_;
 
 private:
+	void unlockLocked();
+
 	void mediaDeviceDisconnected(MediaDevice *media);
 	virtual void disconnect();
 
@@ -81,6 +84,7 @@ private:
 
 	const char *name_;
 
+	Mutex lock_;
 	bool lockOwner_;
 
 	friend class PipelineHandlerFactory;
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 3d61311c..2d2bb940 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -10,6 +10,7 @@
 #include <sys/sysmacros.h>
 
 #include <libcamera/base/log.h>
+#include <libcamera/base/thread.h>
 #include <libcamera/base/utils.h>
 
 #include <libcamera/camera.h>
@@ -150,6 +151,8 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,
  */
 bool PipelineHandler::lock()
 {
+	MutexLocker locker(lock_);
+
 	/* Do not allow nested locking in the same libcamera instance. */
 	if (lockOwner_)
 		return false;
@@ -178,6 +181,13 @@ bool PipelineHandler::lock()
  */
 void PipelineHandler::unlock()
 {
+	MutexLocker locker(lock_);
+
+	unlockLocked();
+}
+
+void PipelineHandler::unlockLocked()
+{
 	if (lockOwner_)
 		return;