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GET /api/1.1/patches/19459/?format=api
{ "id": 19459, "url": "https://patchwork.libcamera.org/api/1.1/patches/19459/?format=api", "web_url": "https://patchwork.libcamera.org/patch/19459/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20240123011249.22716-12-laurent.pinchart@ideasonboard.com>", "date": "2024-01-23T01:12:48", "name": "[v2,11/12] libcamera: object: Document and ensure Object deletion constraints", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": false, "hash": "3a9d3f9b9819506795a1f29fd6da67e8c9ab0c25", "submitter": { "id": 2, "url": "https://patchwork.libcamera.org/api/1.1/people/2/?format=api", "name": "Laurent Pinchart", "email": "laurent.pinchart@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/19459/mbox/", "series": [ { "id": 4157, "url": "https://patchwork.libcamera.org/api/1.1/series/4157/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=4157", "date": "2024-01-23T01:12:37", "name": "libcamera: Hardening against thread race conditions", "version": 2, "mbox": "https://patchwork.libcamera.org/series/4157/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/19459/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/19459/checks/", "tags": {}, "headers": { "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>", "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 66702C32C4\n\tfor <parsemail@patchwork.libcamera.org>;\n\tTue, 23 Jan 2024 01:13:05 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 9335A62955;\n\tTue, 23 Jan 2024 02:13:04 +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 B185362981\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tTue, 23 Jan 2024 02:13:00 +0100 (CET)", "from pendragon.ideasonboard.com (89-27-53-110.bb.dnainternet.fi\n\t[89.27.53.110])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 579661574;\n\tTue, 23 Jan 2024 02:11:47 +0100 (CET)" ], "Authentication-Results": "lancelot.ideasonboard.com;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"SetXkB8W\"; dkim-atps=neutral", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1705972307;\n\tbh=yXzNLkAmP8fw3TYEP74DzvSAHQQJcmQkyhNtpFZydJM=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=SetXkB8Wb28GD/4sS1Cdl1D01jBoC5YQa6EcPKWV2b00sY9kUkAjM2IvgnHPUPKvU\n\to941w1qyrt2fa6uzqCAGKy/y7donBWkmNG74JoWbsdCO9qEfCZfFu8T/5SZLaDGccq\n\ti8N6znhNobvgh3cAFNtz71VxrBHigoHmQwhnsGSo=", "From": "Laurent Pinchart <laurent.pinchart@ideasonboard.com>", "To": "libcamera-devel@lists.libcamera.org", "Subject": "[PATCH v2 11/12] libcamera: object: Document and ensure Object\n\tdeletion constraints", "Date": "Tue, 23 Jan 2024 03:12:48 +0200", "Message-ID": "<20240123011249.22716-12-laurent.pinchart@ideasonboard.com>", "X-Mailer": "git-send-email 2.43.0", "In-Reply-To": "<20240123011249.22716-1-laurent.pinchart@ideasonboard.com>", "References": "<20240123011249.22716-1-laurent.pinchart@ideasonboard.com>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "content": "Object instances are meant to be deleted from the thread they are bound\nto, and this requirement is documented. There are however exceptions to\nthe rule, as threads may be stopped and restarted, with objects bound to\nthem not being deleted and recreated for every stop/restart cycle. Bound\nobjects may therefore need to be deleted after the thread has stopped,\nmaking it impossible to use Object::deleteLater().\n\nDocument the lifetime requirements more precisely, and enforce them with\nan assertion.\n\nSigned-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>\nReviewed-by: Milan Zamazal <mzamazal@redhat.com>\n---\n src/libcamera/base/object.cpp | 16 ++++++++++++++--\n 1 file changed, 14 insertions(+), 2 deletions(-)", "diff": "diff --git a/src/libcamera/base/object.cpp b/src/libcamera/base/object.cpp\nindex 14399d750e03..c6040fc6a78b 100644\n--- a/src/libcamera/base/object.cpp\n+++ b/src/libcamera/base/object.cpp\n@@ -40,8 +40,9 @@ LOG_DEFINE_CATEGORY(Object)\n * Object class.\n *\n * Deleting an object from a thread other than the one the object is bound to is\n- * unsafe, unless the caller ensures that the object isn't processing any\n- * message concurrently.\n+ * unsafe, unless the caller ensures that the object's thread is stopped and no\n+ * parent or child of the object gets deleted concurrently. See\n+ * Object::~Object() for more information.\n *\n * Object slots connected to signals will also run in the context of the\n * object's thread, regardless of whether the signal is emitted in the same or\n@@ -84,9 +85,20 @@ Object::Object(Object *parent)\n * Object instances shall be destroyed from the thread they are bound to,\n * otherwise undefined behaviour may occur. If deletion of an Object needs to\n * be scheduled from a different thread, deleteLater() shall be used.\n+ *\n+ * As an exception to this rule, Object instances may be deleted from a\n+ * different thread if the thread the instance is bound to is stopped through\n+ * the whole duration of the object's destruction, *and* the parent and children\n+ * of the object do not get deleted concurrently. The caller is responsible for\n+ * fulfilling those requirements.\n+ *\n+ * In all cases Object instances shall be deleted before the Thread they are\n+ * bound to.\n */\n Object::~Object()\n {\n+\tASSERT(Thread::current() == thread_ || !thread_->isRunning());\n+\n \t/*\n \t * Move signals to a private list to avoid concurrent iteration and\n \t * deletion of items from Signal::disconnect().\n", "prefixes": [ "v2", "11/12" ] }