[{"id":34550,"web_url":"https://patchwork.libcamera.org/comment/34550/","msgid":"<20250618160916.GG22102@pendragon.ideasonboard.com>","date":"2025-06-18T16:09:16","subject":"Re: [PATCH] EncoderLibJpeg: Fix struct\n\tJPEGPixelFormatInfo::PixelFormatInfo","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Harvey,\n\nThank you for the patch.\n\nOn Wed, Jun 18, 2025 at 12:01:59PM +0000, Harvey Yang wrote:\n> Previously, JPEGPixelFormatInfo::PixelFormatInfo is a const reference.\n> However, the use cases of it are mostly from temporarily constructed\n> instances, which will be destructed right after setting up\n> JPEGPixelFormatInfo.\n\nCould you please explain in more details where those temporary instances\nare destroyed ? JPEGPixelFormatInfo::pixelFormatInfo is populated from\nPixelFormatInfo::info() calls, which should always return a reference to\na const global instance with a lifetime matching the libcamera lifetime.\n\n> To avoid data corruption, JPEGPixelFormatInfo::PixelFormatInfo should be\n> a pure constant member variable instead.\n> \n> Signed-off-by: Harvey Yang \n> ---\n> src/android/jpeg/encoder_libjpeg.cpp | 2 +-\n> 1 file changed, 1 insertion(+), 1 deletion(-)\n> \n> diff --git a/src/android/jpeg/encoder_libjpeg.cpp b/src/android/jpeg/encoder_libjpeg.cpp\n> index cb242b5ec6a8..0c088535f0be 100644\n> --- a/src/android/jpeg/encoder_libjpeg.cpp\n> +++ b/src/android/jpeg/encoder_libjpeg.cpp\n> @@ -34,7 +34,7 @@ namespace {\n> \n> struct JPEGPixelFormatInfo {\n> \tJ_COLOR_SPACE colorSpace;\n> -\tconst PixelFormatInfo &pixelFormatInfo;\n> +\tconst PixelFormatInfo pixelFormatInfo;\n> \tbool nvSwap;\n> };\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 E0142BDE6B\n\tfor ;\n\tWed, 18 Jun 2025 16:09:36 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id F1EDE68DC1;\n\tWed, 18 Jun 2025 18:09:35 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id F0CEC68DC1\n\tfor ;\n\tWed, 18 Jun 2025 18:09:33 +0200 (CEST)","from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi\n\t[81.175.209.231])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 84442752;\n\tWed, 18 Jun 2025 18:09:20 +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=\"ZOSnFswu\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1750262960;\n\tbh=O1m6G8WWAYHdtMnQ/hJo88vhEesf+VuoQQ/zZJYzyZE=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=ZOSnFswuxHeQ4qDuXRXRKoutUobRRh7uP1Ns9BBmTqV/ztNfKDEIBU8yLagHVOpDQ\n\tx50a4L8Bsx4vvf/hRbwg3g7dLEJS+lahdPNFfHi6IANYquqW8AaTy8WtZkfdNZplHL\n\tdq2SUQMelOsc8b8TJGW26lbNjc+5Kv7qwuwrUM30=","Date":"Wed, 18 Jun 2025 19:09:16 +0300","From":"Laurent Pinchart ","To":"Harvey Yang ","Cc":"libcamera-devel@lists.libcamera.org,\n\tHarvey Yang ","Subject":"Re: [PATCH] EncoderLibJpeg: Fix struct\n\tJPEGPixelFormatInfo::PixelFormatInfo","Message-ID":"<20250618160916.GG22102@pendragon.ideasonboard.com>","References":"<20250618120204.3047218-1-chenghaoyang@google.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<20250618120204.3047218-1-chenghaoyang@google.com>","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\" "}},{"id":34553,"web_url":"https://patchwork.libcamera.org/comment/34553/","msgid":"","date":"2025-06-19T05:39:52","subject":"Re: [PATCH] EncoderLibJpeg: Fix struct\n\tJPEGPixelFormatInfo::PixelFormatInfo","submitter":{"id":117,"url":"https://patchwork.libcamera.org/api/people/117/","name":"Cheng-Hao Yang","email":"chenghaoyang@chromium.org"},"content":"Hi Laurent,\n\nOn Thu, Jun 19, 2025 at 12:09 AM Laurent Pinchart\n wrote:\n>\n> Hi Harvey,\n>\n> Thank you for the patch.\n>\n> On Wed, Jun 18, 2025 at 12:01:59PM +0000, Harvey Yang wrote:\n> > Previously, JPEGPixelFormatInfo::PixelFormatInfo is a const reference.\n> > However, the use cases of it are mostly from temporarily constructed\n> > instances, which will be destructed right after setting up\n> > JPEGPixelFormatInfo.\n>\n> Could you please explain in more details where those temporary instances\n> are destroyed ? JPEGPixelFormatInfo::pixelFormatInfo is populated from\n> PixelFormatInfo::info() calls, which should always return a reference to\n> a const global instance with a lifetime matching the libcamera lifetime.\n\nAh yes, you're right. I misunderstood the failure I encountered:\nI'm running libcamera on Android, and it's that const global\n`pixelInfo` in `encoder_libjpeg.cpp` is initialized before\nconst global `pixelFormatInfo` in `formats.cpp`, even if\n`formats.cpp` is wrapped in the base libcamera shared library,\nand the android adapter (which contains `encoder_libjpeg.cpp`)\ndepends on the base libcamera shared library.\nIt seems that C++ initialization order doesn't follow the linking\nprocess...\n\nPlease check if it makes sense to you, and I'll upload another\npatch to put `pixelFormatInfo` in a static function in PixelFormatInfo.\nLet me know if there's a more proper fix.\n\nThanks,\nHarvey\n\n>\n> > To avoid data corruption, JPEGPixelFormatInfo::PixelFormatInfo should be\n> > a pure constant member variable instead.\n> >\n> > Signed-off-by: Harvey Yang \n> > ---\n> > src/android/jpeg/encoder_libjpeg.cpp | 2 +-\n> > 1 file changed, 1 insertion(+), 1 deletion(-)\n> >\n> > diff --git a/src/android/jpeg/encoder_libjpeg.cpp b/src/android/jpeg/encoder_libjpeg.cpp\n> > index cb242b5ec6a8..0c088535f0be 100644\n> > --- a/src/android/jpeg/encoder_libjpeg.cpp\n> > +++ b/src/android/jpeg/encoder_libjpeg.cpp\n> > @@ -34,7 +34,7 @@ namespace {\n> >\n> > struct JPEGPixelFormatInfo {\n> > J_COLOR_SPACE colorSpace;\n> > - const PixelFormatInfo &pixelFormatInfo;\n> > + const PixelFormatInfo pixelFormatInfo;\n> > bool nvSwap;\n> > };\n> >\n>\n> --\n> Regards,\n>\n> Laurent Pinchart","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 74D7AC3237\n\tfor ;\n\tThu, 19 Jun 2025 05:40:08 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id E940F68DCC;\n\tThu, 19 Jun 2025 07:40:06 +0200 (CEST)","from mail-lj1-x22f.google.com (mail-lj1-x22f.google.com\n\t[IPv6:2a00:1450:4864:20::22f])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 6ABAA61535\n\tfor ;\n\tThu, 19 Jun 2025 07:40:04 +0200 (CEST)","by mail-lj1-x22f.google.com with SMTP id\n\t38308e7fff4ca-32b43846e8cso3194681fa.0\n\tfor ;\n\tWed, 18 Jun 2025 22:40:04 -0700 (PDT)"],"Authentication-Results":"lancelot.ideasonboard.com; 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