{"id":22905,"url":"https://patchwork.libcamera.org/api/1.1/patches/22905/?format=json","web_url":"https://patchwork.libcamera.org/patch/22905/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20250303142010.714280-1-barnabas.pocze@ideasonboard.com>","date":"2025-03-03T14:20:10","name":"[v1] libcamera: camera_manager: Do not emit signals while holding lock","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"feef204119ffdedb2eb3bfe209ff7b51af6633ce","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/1.1/people/216/?format=json","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/22905/mbox/","series":[{"id":5033,"url":"https://patchwork.libcamera.org/api/1.1/series/5033/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5033","date":"2025-03-03T14:20:10","name":"[v1] libcamera: camera_manager: Do not emit signals while holding lock","version":1,"mbox":"https://patchwork.libcamera.org/series/5033/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/22905/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/22905/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 3B336BD808\n\tfor ;\n\tMon, 3 Mar 2025 14:20:18 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 2549A687EB;\n\tMon, 3 Mar 2025 15:20:17 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 0064268772\n\tfor ;\n\tMon, 3 Mar 2025 15:20:14 +0100 (CET)","from pb-laptop.local (185.221.143.4.nat.pool.zt.hu [185.221.143.4])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 79264346\n\tfor ;\n\tMon, 3 Mar 2025 15:18:43 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"ACTlZ9Z8\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1741011523;\n\tbh=c4r/pJEhhSyInFGPBj6pSe19gl3oxdCK4R9br25tVOg=;\n\th=From:To:Subject:Date:From;\n\tb=ACTlZ9Z8/b88q0vhkEhPqI9bJvduYKu5mD7Fl4ins99F+uIsQJxPOQmwYN05NmdaJ\n\t48k1ftdX25z83333cQ9dDOd1vfaqACIvno81GPUjvKHPus1f2S8B5E6VLyYqF07TUx\n\tS/49ywDZQdJ4qo52XT2ry286VS8dqf6l6RSWFFew=","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"libcamera-devel@lists.libcamera.org","Subject":"[PATCH v1] libcamera: camera_manager: Do not emit signals while\n\tholding lock","Date":"Mon, 3 Mar 2025 15:20:10 +0100","Message-ID":"<20250303142010.714280-1-barnabas.pocze@ideasonboard.com>","X-Mailer":"git-send-email 2.48.1","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"Both `CameraManager::Private::{add,remove}Camera()` emit the\n`camera{Added,Removed}` signals, respectively, while holding the\nlock protecting the list of cameras.\n\nThis is problematic because if a callback tries to call `cameras()`,\nthen the same (non-recursive) lock would be locked again.\n\nFurthermore, there is no real need to hold the lock while user code\nis running, so release the lock as soon as possible.\n\nSigned-off-by: Barnabás Pőcze \n---\n src/libcamera/camera_manager.cpp | 16 +++++++++-------\n 1 file changed, 9 insertions(+), 7 deletions(-)","diff":"diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp\nindex 87e6717ec..d728ac44a 100644\n--- a/src/libcamera/camera_manager.cpp\n+++ b/src/libcamera/camera_manager.cpp\n@@ -202,6 +202,7 @@ void CameraManager::Private::addCamera(std::shared_ptr camera)\n {\n \tASSERT(Thread::current() == this);\n \n+{\n \tMutexLocker locker(mutex_);\n \n \tfor (const std::shared_ptr &c : cameras_) {\n@@ -213,13 +214,12 @@ void CameraManager::Private::addCamera(std::shared_ptr camera)\n \t\t}\n \t}\n \n-\tcameras_.push_back(std::move(camera));\n-\n-\tunsigned int index = cameras_.size() - 1;\n+\tcameras_.push_back(camera);\n+}\n \n \t/* Report the addition to the public signal */\n \tCameraManager *const o = LIBCAMERA_O_PTR();\n-\to->cameraAdded.emit(cameras_[index]);\n+\to->cameraAdded.emit(std::move(camera));\n }\n \n /**\n@@ -236,6 +236,7 @@ void CameraManager::Private::removeCamera(std::shared_ptr camera)\n {\n \tASSERT(Thread::current() == this);\n \n+{\n \tMutexLocker locker(mutex_);\n \n \tauto iter = std::find_if(cameras_.begin(), cameras_.end(),\n@@ -245,14 +246,15 @@ void CameraManager::Private::removeCamera(std::shared_ptr camera)\n \tif (iter == cameras_.end())\n \t\treturn;\n \n+\tcameras_.erase(iter);\n+}\n+\n \tLOG(Camera, Debug)\n \t\t<< \"Unregistering camera '\" << camera->id() << \"'\";\n \n-\tcameras_.erase(iter);\n-\n \t/* Report the removal to the public signal */\n \tCameraManager *const o = LIBCAMERA_O_PTR();\n-\to->cameraRemoved.emit(camera);\n+\to->cameraRemoved.emit(std::move(camera));\n }\n \n /**\n","prefixes":["v1"]}