[{"id":5041,"web_url":"https://patchwork.libcamera.org/comment/5041/","msgid":"<20200605101603.GF5852@pendragon.ideasonboard.com>","date":"2020-06-05T10:16:03","subject":"Re: [libcamera-devel] [PATCH v2 4/7] v4l2: v4l2_camera_proxy:\n\tAcquire only one buffer semaphore on VIDIOC_DQBUF","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Paul,\n\nThank you for the patch.\n\nOn Fri, Jun 05, 2020 at 06:01:03PM +0900, Paul Elder wrote:\n> We use a semaphore to atomically keep track of how many buffers are\n> available for dequeueing. The check for how to acquire the semaphore was\n> incorrect, leading to a double acquire upon a successful nonblocking\n> acquire. Fix this.\n> \n> Signed-off-by: Paul Elder \n\nReviewed-by: Laurent Pinchart \n\n> \n> ---\n> Changes in v2: restructured the if block so it's easier to read\n> ---\n> src/v4l2/v4l2_camera_proxy.cpp | 6 +++---\n> 1 file changed, 3 insertions(+), 3 deletions(-)\n> \n> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp\n> index ec6d265d..a0c6deea 100644\n> --- a/src/v4l2/v4l2_camera_proxy.cpp\n> +++ b/src/v4l2/v4l2_camera_proxy.cpp\n> @@ -426,10 +426,10 @@ int V4L2CameraProxy::vidioc_dqbuf(struct v4l2_buffer *arg)\n> \t !validateMemoryType(arg->memory))\n> \t\treturn -EINVAL;\n> \n> -\tif (nonBlocking_ && !vcam_->bufferSema_.tryAcquire())\n> -\t\treturn -EAGAIN;\n> -\telse\n> +\tif (!nonBlocking_)\n> \t\tvcam_->bufferSema_.acquire();\n> +\telse if (!vcam_->bufferSema_.tryAcquire())\n> +\t\treturn -EAGAIN;\n> \n> \tupdateBuffers();\n>","headers":{"Return-Path":"","Received":["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 06BBB603C9\n\tfor ;\n\tFri, 5 Jun 2020 12:16:21 +0200 (CEST)","from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi\n\t[81.175.216.236])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 9C79B27C;\n\tFri, 5 Jun 2020 12:16:20 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"vDxRWaS7\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1591352180;\n\tbh=6HIIB7rWEVDjN5qyaiLOTrBg9HFuNbdoV0Ukn4LueA4=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=vDxRWaS74cfeDZo99DWaF+z/RUNwupT2eZGIfO7PK/fLt6CIKG3hiHxRk2OK8OO0m\n\tsgvNriiG6TdU/EYyBHaRup6l73m8YqPtzDzQE41sGqevV+yzOMPiJPigMJE1NmsTOn\n\tI4kO0dOw7HozFEXSikgDV2bLtgKGh5nv0nA6FSZ8=","Date":"Fri, 5 Jun 2020 13:16:03 +0300","From":"Laurent Pinchart ","To":"Paul Elder ","Cc":"libcamera-devel@lists.libcamera.org","Message-ID":"<20200605101603.GF5852@pendragon.ideasonboard.com>","References":"<20200605090106.15424-1-paul.elder@ideasonboard.com>\n\t<20200605090106.15424-5-paul.elder@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<20200605090106.15424-5-paul.elder@ideasonboard.com>","Subject":"Re: [libcamera-devel] [PATCH v2 4/7] v4l2: v4l2_camera_proxy:\n\tAcquire only one buffer semaphore on VIDIOC_DQBUF","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","X-List-Received-Date":"Fri, 05 Jun 2020 10:16:21 -0000"}},{"id":5056,"web_url":"https://patchwork.libcamera.org/comment/5056/","msgid":"<20200605181824.GG5864@oden.dyn.berto.se>","date":"2020-06-05T18:18:24","subject":"Re: [libcamera-devel] [PATCH v2 4/7] v4l2: v4l2_camera_proxy:\n\tAcquire only one buffer semaphore on VIDIOC_DQBUF","submitter":{"id":5,"url":"https://patchwork.libcamera.org/api/people/5/","name":"Niklas Söderlund","email":"niklas.soderlund@ragnatech.se"},"content":"Hi Paul,\n\nThanks for your patch.\n\nOn 2020-06-05 18:01:03 +0900, Paul Elder wrote:\n> We use a semaphore to atomically keep track of how many buffers are\n> available for dequeueing. The check for how to acquire the semaphore was\n> incorrect, leading to a double acquire upon a successful nonblocking\n> acquire. Fix this.\n> \n> Signed-off-by: Paul Elder \n\nReviewed-by: Niklas Söderlund \n\n> \n> ---\n> Changes in v2: restructured the if block so it's easier to read\n> ---\n> src/v4l2/v4l2_camera_proxy.cpp | 6 +++---\n> 1 file changed, 3 insertions(+), 3 deletions(-)\n> \n> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp\n> index ec6d265d..a0c6deea 100644\n> --- a/src/v4l2/v4l2_camera_proxy.cpp\n> +++ b/src/v4l2/v4l2_camera_proxy.cpp\n> @@ -426,10 +426,10 @@ int V4L2CameraProxy::vidioc_dqbuf(struct v4l2_buffer *arg)\n> \t !validateMemoryType(arg->memory))\n> \t\treturn -EINVAL;\n> \n> -\tif (nonBlocking_ && !vcam_->bufferSema_.tryAcquire())\n> -\t\treturn -EAGAIN;\n> -\telse\n> +\tif (!nonBlocking_)\n> \t\tvcam_->bufferSema_.acquire();\n> +\telse if (!vcam_->bufferSema_.tryAcquire())\n> +\t\treturn -EAGAIN;\n> \n> \tupdateBuffers();\n> \n> -- \n> 2.20.1\n> \n> _______________________________________________\n> libcamera-devel mailing list\n> libcamera-devel@lists.libcamera.org\n> https://lists.libcamera.org/listinfo/libcamera-devel","headers":{"Return-Path":"","Received":["from mail-lj1-x244.google.com (mail-lj1-x244.google.com\n\t[IPv6:2a00:1450:4864:20::244])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 30F82603C6\n\tfor ;\n\tFri, 5 Jun 2020 20:18:26 +0200 (CEST)","by mail-lj1-x244.google.com with SMTP id z9so12856458ljh.13\n\tfor ;\n\tFri, 05 Jun 2020 11:18:26 -0700 (PDT)","from localhost (h-209-203.A463.priv.bahnhof.se. 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