[{"id":34728,"web_url":"https://patchwork.libcamera.org/comment/34728/","msgid":"<175127242065.2340557.11505298535379477422@ping.linuxembedded.co.uk>","date":"2025-06-30T08:33:40","subject":"Re: [PATCH v1 6/6] libcamera: pipeline_handler: cancel waiting\n\trequests first","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Stefan Klug (2025-06-30 09:11:21)\n> From: Kieran Bingham \n> \n> When stopping a camera, we may now find that there are requests\n> queued to the camera but not yet available in the pipeline handler.\n> \n> These are \"waitingReqeusts\" which are not yet queued to the device.\n> \n> While stopping a camera, we ask the pipeline to stop with stopDevice()\n> and then cancel any waiting requests after.\n> \n> This however can lead to a race where having stopped the camera and\n> completed the requests, the pipeline may try to further consume requests\n> from the waiting lists.\n> \n> Therefore empty the waitingRequests queue before stopping the device and\n> cancel the waitingRequests afterwards.\n> \n> Signed-off-by: Kieran Bingham \n> Signed-off-by: Stefan Klug \n\nThat's most of a rewrite - so I don't know who the author is now - but\nindeed, based on previous review comments this looks good to me!\n\n\nReviewed-by: Kieran Bingham \n\n... But I'm reviewing your modifications not a patch I wrote ;-) \n\n\n> ---\n> src/libcamera/pipeline_handler.cpp | 18 +++++++++++++-----\n> 1 file changed, 13 insertions(+), 5 deletions(-)\n> \n> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> index 383c6ad0c4aa..207a2bae96d6 100644\n> --- a/src/libcamera/pipeline_handler.cpp\n> +++ b/src/libcamera/pipeline_handler.cpp\n> @@ -364,20 +364,28 @@ void PipelineHandler::unlockMediaDevices()\n> */\n> void PipelineHandler::stop(Camera *camera)\n> {\n> + /*\n> + * Take all waiting requests so that they are not requeued in response\n> + * to completeRequest() being called inside stopDevice(). Cancel them\n> + * after the device to keep them in order.\n> + */\n> + Camera::Private *data = camera->_d();\n> + std::queue waitingRequests;\n> + waitingRequests.swap(data->waitingRequests_);\n> +\n> /* Stop the pipeline handler and let the queued requests complete. */\n> stopDevice(camera);\n> \n> - Camera::Private *data = camera->_d();\n> -\n> /* Cancel and signal as complete all waiting requests. */\n> - while (!data->waitingRequests_.empty()) {\n> - Request *request = data->waitingRequests_.front();\n> - data->waitingRequests_.pop();\n> + while (!waitingRequests.empty()) {\n> + Request *request = waitingRequests.front();\n> + waitingRequests.pop();\n> cancelRequest(request);\n> }\n> \n> /* Make sure no requests are pending. */\n> ASSERT(data->queuedRequests_.empty());\n> + ASSERT(data->waitingRequests_.empty());\n> \n> data->requestSequence_ = 0;\n> }\n> -- \n> 2.48.1\n>","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 A4166BDCBF\n\tfor ;\n\tMon, 30 Jun 2025 08:33:45 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id C685168E05;\n\tMon, 30 Jun 2025 10:33:44 +0200 (CEST)","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 5031761529\n\tfor ;\n\tMon, 30 Jun 2025 10:33:43 +0200 (CEST)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id A04456BE;\n\tMon, 30 Jun 2025 10:33:21 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"Kk7AEfrs\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1751272401;\n\tbh=kxAu9hd/juNj4nbHsZd2mvDmNSOBZ9W5qDbMgEcDgX0=;\n\th=In-Reply-To:References:Subject:From:Cc:To:Date:From;\n\tb=Kk7AEfrsle2eGd4XvHX6ThcF2O8mAT4kYMskQ1XuwVzf/XpJYPYSRCNKWPo4nJMf6\n\tr1c32t5/WKhTtIvRtZwht6QcVI1bKJa+cIjdSNxdYW9iMcaODFp3oqsiuGBYi6VdAo\n\tfzPI/JOmddfbFEtHiFCasyPCuUrc//myQEowZ+uA=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20250630081126.2384387-7-stefan.klug@ideasonboard.com>","References":"<20250630081126.2384387-1-stefan.klug@ideasonboard.com>\n\t<20250630081126.2384387-7-stefan.klug@ideasonboard.com>","Subject":"Re: [PATCH v1 6/6] libcamera: pipeline_handler: cancel waiting\n\trequests first","From":"Kieran Bingham ","Cc":"Stefan Klug ","To":"Stefan Klug ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Mon, 30 Jun 2025 09:33:40 +0100","Message-ID":"<175127242065.2340557.11505298535379477422@ping.linuxembedded.co.uk>","User-Agent":"alot/0.9.1","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\" "}}]