From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 79B23308F2E for ; Mon, 13 Oct 2025 14:15:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760364948; cv=none; b=a8G7jfm/iyfJnTbqn9QZ43kBl4iCG9m6/z2ghaGQn+MGRrC1GXGwuTp0JhaSEZ6KZLoAudOK1NUXQeQy3xdSNK6/z9esWAwH95BvZEti7kp/II4qj9Ifa1Ekn3nwgMLvxgjomWCYn5PnhLndolvcA2LVCDWDt4HMyu8nBBGSTgk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760364948; c=relaxed/simple; bh=X6/q1bHsLK+ZhgGEzfdnTYkllaQ39VA9H94eFOB9hyg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ep8/iGJVckgOaqSAa704p/NKaQsPkU6NQOOlO1cqci9diYNf2ITSACUvqEKbGDe5VX2rw9gbjr44IsOoanrtr/Op8d4LoNZsH4ZeW0j8wRsIRNEdZSVBM4oWeuAf96CZQ4EYnJJLYBkHI0U5aQjh+d5yinbYixAQfTNEf/8ob44= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OxvJ9B5+; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OxvJ9B5+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1760364945; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9uIgQtAlSBtKcFSO9NiV0X395eAsPo0/3pZRzpykst8=; b=OxvJ9B5+Ov0+JYuUbY/CpHKdEMN8k9UsUM/YcDt+ySUsd//bH/N+I23vdQmxQPitI2GkdM 6rLS0m44nKF2PFpiHdY9wM8mXdrCEqqpTgZCrq+m0igJmHAkn94ZIOATPfRn8Z+HdV9pBU QBvUt5nU8mDSsb6+enDMKP2R6ktuFeY= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-237-C4xh4F-QMm-CDU2SV2wIIQ-1; Mon, 13 Oct 2025 10:15:44 -0400 X-MC-Unique: C4xh4F-QMm-CDU2SV2wIIQ-1 X-Mimecast-MFC-AGG-ID: C4xh4F-QMm-CDU2SV2wIIQ_1760364943 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-46b303f6c9cso39068105e9.2 for ; Mon, 13 Oct 2025 07:15:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760364943; x=1760969743; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=9uIgQtAlSBtKcFSO9NiV0X395eAsPo0/3pZRzpykst8=; b=AzZKx7QOlF3OJT7Bd2pzVuOMYjxqaCnl2/5aAFgyZNCjAAFI9FIXmBYhTPzZaPZ4pu tcvRft3D9cNBX+8sbKAPFO6xzsPOS7siU86cbUX2l/T//hTtcbVjTDtxBw33VuaRSzot hdb2BltZxb6V7gpc1dr75Y1Y26P5gfDkJ9rGwA9bbzdbBt3BAb0XXEUmf9fvqjC5rA+c s69OB5e6Jtccyfn0kJXdWUVcMkn86NQgbEA9G/67C5qrUNrgqxDGZHVSUdNyZLFoLeAZ Qd94B9g6NWZ44AFUmMWtAaM9AJXmfJTJxmYsCH4UuAVHDK54zlYDnDsEXaaioPYWyaPz PzEw== X-Forwarded-Encrypted: i=1; AJvYcCUIC3fRsHgJ+vayoKBWkDei9tSZmC+ukz7FL89EXuam/IBeAJaKzHWujjV8OtP986Fp0FaJDRA=@vger.kernel.org X-Gm-Message-State: AOJu0YxxWDnipF2KGG6iDL+Evp0feaDmI8kw82jbzcHACfkk4wGiF7B2 3Y/BRqpzCR8K0xs3eZLIraS0i5K+mSzL8xQLHg8jY5zKYh0WqqdJK249QJuNuoh4u5IePQvZG6n BJpDTaUCZqLB70YgYoqauX///rtsZ4vP7yuBiqcGWf79BRI8vK64UA8z6yw== X-Gm-Gg: ASbGncuMFaAjmQ17gq4IxRZ/fds8qpyu7YHQhtfsbP7MpclDNeYNbujONGz85nojsP1 xUSmdHfZCF3sMqK0VPh8yNMVd9f1Jpox3Y0z9w++K/JqwLTx9VZReoJEzAReHju8U/zQnS35It5 e79yKa+cBr3jXK4MxPp7BTKBPmHmx0hLRNmym0fhdftYI/J66N0OI8Mtnjix2qWYM8Dcvs6y+yL JYfmizDCzJ6GSUDsb4tlhvIrHzHu4brjpU00kQfCCUpRxqcktxBw7+uaiVLtvgb9k/Q8YKScIra 0wsVIMw8DvbVYoMVv+DWdNjUamfldd6uFw== X-Received: by 2002:a05:600c:502c:b0:46e:3d41:5fe6 with SMTP id 5b1f17b1804b1-46fa9a9ebb8mr139543335e9.9.1760364942887; Mon, 13 Oct 2025 07:15:42 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFR9AfQG1bPxhSVGiAWctJCWR2+PTWw1bYga2tLxdTe6Ieug+DROBY5xi12o8AGOXPV/OiFfQ== X-Received: by 2002:a05:600c:502c:b0:46e:3d41:5fe6 with SMTP id 5b1f17b1804b1-46fa9a9ebb8mr139543115e9.9.1760364942471; Mon, 13 Oct 2025 07:15:42 -0700 (PDT) Received: from fedora ([2a01:e0a:257:8c60:80f1:cdf8:48d0:b0a1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fab3e3520sm136542145e9.2.2025.10.13.07.15.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Oct 2025 07:15:41 -0700 (PDT) Date: Mon, 13 Oct 2025 16:15:40 +0200 From: Matias Ezequiel Vara Larsen To: Francesco Valla Cc: Marc Kleine-Budde , Paolo Abeni , Harald Mommer , Mikhail Golubev-Ciuchea , Wolfgang Grandegger , Eric Dumazet , Jakub Kicinski , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Damir Shaikhutdinov , linux-kernel@vger.kernel.org, linux-can@vger.kernel.org, netdev@vger.kernel.org, virtualization@lists.linux.dev, development@redaril.me Subject: Re: [PATCH v5] can: virtio: Initial virtio CAN driver. Message-ID: References: <20240108131039.2234044-1-Mikhail.Golubev-Ciuchea@opensynergy.com> <2243144.yiUUSuA9gR@fedora.fritz.box> <2318164.vFx2qVVIhK@fedora.fritz.box> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2318164.vFx2qVVIhK@fedora.fritz.box> On Fri, Oct 10, 2025 at 11:20:22PM +0200, Francesco Valla wrote: > On Friday, 10 October 2025 at 17:46:25 Matias Ezequiel Vara Larsen wrote: > > On Thu, Sep 11, 2025 at 10:59:40PM +0200, Francesco Valla wrote: > > > Hello Mikhail, Harald, > > > > > > hoping there will be a v6 of this patch soon, a few comments: > > > > > > > I am working on the v6 by addressing the comments in this thread. > > > > > On Monday, 8 January 2024 at 14:10:35 Mikhail Golubev-Ciuchea wrote: > > > > > > [...] > > > > > > > + > > > > +/* virtio_can private data structure */ > > > > +struct virtio_can_priv { > > > > + struct can_priv can; /* must be the first member */ > > > > + /* NAPI for RX messages */ > > > > + struct napi_struct napi; > > > > + /* NAPI for TX messages */ > > > > + struct napi_struct napi_tx; > > > > + /* The network device we're associated with */ > > > > + struct net_device *dev; > > > > + /* The virtio device we're associated with */ > > > > + struct virtio_device *vdev; > > > > + /* The virtqueues */ > > > > + struct virtqueue *vqs[VIRTIO_CAN_QUEUE_COUNT]; > > > > + /* I/O callback function pointers for the virtqueues */ > > > > + vq_callback_t *io_callbacks[VIRTIO_CAN_QUEUE_COUNT]; > > > > + /* Lock for TX operations */ > > > > + spinlock_t tx_lock; > > > > + /* Control queue lock. Defensive programming, may be not needed */ > > > > + struct mutex ctrl_lock; > > > > + /* Wait for control queue processing without polling */ > > > > + struct completion ctrl_done; > > > > + /* List of virtio CAN TX message */ > > > > + struct list_head tx_list; > > > > + /* Array of receive queue messages */ > > > > + struct virtio_can_rx rpkt[128]; > > > > > > This array should probably be allocated dynamically at probe - maybe > > > using a module parameter instead of a hardcoded value as length? > > > > > > > If I allocate this array in probe(), I would not know sdu[] in advance > > if I defined it as a flexible array. That made me wonder: can sdu[] be > > defined as flexible array for rx? > > > > Thanks. > > > > One thing that can be done is to define struct virtio_can_rx as: > > struct virtio_can_rx { > #define VIRTIO_CAN_RX 0x0101 > __le16 msg_type; > __le16 length; /* 0..8 CC, 0..64 CAN-FD, 0..2048 CAN-XL, 12 bits */ > __u8 reserved_classic_dlc; /* If CAN classic length = 8 then DLC can be 8..15 */ > __u8 padding; > __le16 reserved_xl_priority; /* May be needed for CAN XL priority */ > __le32 flags; > __le32 can_id; > __u8 sdu[] __counted_by(length); > }; > > and then allocate the rpkt[] array using the maximum length for SDU: > > priv->rpkt = kcalloc(num_rx_buffers, > sizeof(struct virtio_can_rx) + VIRTIO_CAN_MAX_DLEN, > GFP_KERNEL); > > In this way, the size of each member of rpkt[] is known and is thus > suitable for virtio_can_populate_vqs(). > > >From the spec, VIRTIO_CAN_MAX_DLEN shall be 2048 bytes that corresponds with CAN-XL frame. Matias