NekoCWD/libcamera
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libcamera: camera_manager: Do not emit signals while holding lock

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Both `CameraManager::Private::{add,remove}Camera()` emit the
`camera{Added,Removed}` signals, respectively, while holding the
lock protecting the list of cameras.

This is problematic because if a callback tries to call `cameras()`,
then the same (non-recursive) lock would be locked again.

Furthermore, there is no real need to hold the lock while user code
is running, so release the lock as soon as possible.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Harvey Yang <chenghaoyang@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Barnabás Pőcze 2025-02-06 15:59:42 +01:00
parent b3272f7827
commit d505bd5360
1 changed files with 23 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

14
src/libcamera/camera_manager.cpp
View file

@ -202,6 +202,7 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera)
{
ASSERT(Thread::current() == this);
{
MutexLocker locker(mutex_);
for (const std::shared_ptr<Camera> &c : cameras_) {
@ -213,13 +214,12 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera)
}
}
cameras_.push_back(std::move(camera));
unsigned int index = cameras_.size() - 1;
cameras_.push_back(camera);
}
/* Report the addition to the public signal */
CameraManager *const o = LIBCAMERA_O_PTR();
o->cameraAdded.emit(cameras_[index]);
o->cameraAdded.emit(camera);
}
/**
@ -236,6 +236,7 @@ void CameraManager::Private::removeCamera(std::shared_ptr<Camera> camera)
{
ASSERT(Thread::current() == this);
{
MutexLocker locker(mutex_);
auto iter = std::find_if(cameras_.begin(), cameras_.end(),
@ -245,11 +246,12 @@ void CameraManager::Private::removeCamera(std::shared_ptr<Camera> camera)
if (iter == cameras_.end())
return;
cameras_.erase(iter);
}
LOG(Camera, Debug)
<< "Unregistering camera '" << camera->id() << "'";
cameras_.erase(iter);
/* Report the removal to the public signal */
CameraManager *const o = LIBCAMERA_O_PTR();
o->cameraRemoved.emit(camera);