From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC163C07E9B for ; Sun, 4 Jul 2021 09:54:42 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7E9E661248 for ; Sun, 4 Jul 2021 09:54:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E9E661248 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 3B365402C1; Sun, 4 Jul 2021 09:54:42 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id C6qFn1_s67oD; Sun, 4 Jul 2021 09:54:41 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp2.osuosl.org (Postfix) with ESMTPS id 8F0BD40001; Sun, 4 Jul 2021 09:54:40 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6105AC001A; Sun, 4 Jul 2021 09:54:40 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6C768C000E for ; Sun, 4 Jul 2021 09:54:39 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 5989B60737 for ; Sun, 4 Jul 2021 09:54:39 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp3.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 46uUTdaYrPHJ for ; Sun, 4 Jul 2021 09:54:38 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by smtp3.osuosl.org (Postfix) with ESMTPS id 4B1246072C for ; Sun, 4 Jul 2021 09:54:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625392476; 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=VYPXgNYdb3c09oXqHPIxazq2MDtMHdph5d1ic1D1Bi8=; b=hu4Qn8oQ7Vk9HRFIRoKRhWEcu57eAc2nYE/E571CyiU7FQLtGxU1W87flSGDIdB4ikLDlE YXHbC3RZ7U3IWUTi64ELM0xGm3f1cn+nZEGMSHXOXQ+u8r8KV1REzDnf1dI1W+RjmifL17 umvRdSQobi1XqxqUlvHGoDvUlVAGXHU= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-121-dZGRRxXAP4-TIGOWXecT6g-1; Sun, 04 Jul 2021 05:54:35 -0400 X-MC-Unique: dZGRRxXAP4-TIGOWXecT6g-1 Received: by mail-wr1-f69.google.com with SMTP id x8-20020a5d54c80000b029012583535285so5421399wrv.8 for ; Sun, 04 Jul 2021 02:54:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=VYPXgNYdb3c09oXqHPIxazq2MDtMHdph5d1ic1D1Bi8=; b=fPKISynlLgmepjEd5HDnIB/Eor/D78OMpCWlM1lwZ1SknpAB/E3p8mEz+s3HwOoYUG Cm7YxHZ3+d5BWY361Q4MoDxffUL+JnIb1pOTcoRlQIU39/V2P/uWYVWVIVPC+B4r2Crw 6M7BEwcObUd81eQCsgCHr/ic37FoqnRmbSypRWWYx4g+6hunIvNCVu/YIb7TbX7xej+u KlUx+qkkBAfgDnnhUNkdSi0r+E3/fXM8J5XVXMYxAtIMtLnR196iQx00nYRzX4fKGmgo /EVb3ojxfP1+oSo9hKWqQxi0962cTISpyVg5Y48NQG59KoiavLiJk9Zv8fPjadSLSVyv /n7Q== X-Gm-Message-State: AOAM533hdjqJEC2W+OuuSGMr9hRkc6S1xbGyWkNr0zXIdNttNAbNepfw mGtilTMhEkiyF21jTJFGnQHcyYVtg4NVjdlrC/8CGpfQv/H7m9ua0KRM3yKDFnpLrM6eUv/iQZF zYJDdgPCYbuIBYpKz3ATNQ+5liMIAKIramssCW1K3Ww== X-Received: by 2002:a7b:c8d9:: with SMTP id f25mr8743139wml.153.1625392474342; Sun, 04 Jul 2021 02:54:34 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyWmhMPJZJ9uEg3kxS9p3QQw859N5k7H/UO+tCXIvTNNDhdZj57iiThsIDoBtYfE9gIxTqrUg== X-Received: by 2002:a7b:c8d9:: with SMTP id f25mr8743122wml.153.1625392474177; Sun, 04 Jul 2021 02:54:34 -0700 (PDT) Received: from redhat.com ([2.55.4.39]) by smtp.gmail.com with ESMTPSA id c12sm10458200wrr.90.2021.07.04.02.54.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jul 2021 02:54:33 -0700 (PDT) Date: Sun, 4 Jul 2021 05:54:29 -0400 From: "Michael S. Tsirkin" To: Arseny Krasnov Subject: Re: [RFC PATCH v2 0/6] Improve SOCK_SEQPACKET receive logic Message-ID: <20210704055037-mutt-send-email-mst@kernel.org> References: <20210704080820.88746-1-arseny.krasnov@kaspersky.com> <20210704042843-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: Andra Paraschiv , "kvm@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "oxffffaa@gmail.com" , Norbert Slusarek , Stefan Hajnoczi , Colin Ian King , Jakub Kicinski , "David S. Miller" X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Sun, Jul 04, 2021 at 12:23:03PM +0300, Arseny Krasnov wrote: > > On 04.07.2021 11:30, Michael S. Tsirkin wrote: > > On Sun, Jul 04, 2021 at 11:08:13AM +0300, Arseny Krasnov wrote: > >> This patchset modifies receive logic for SOCK_SEQPACKET. > >> Difference between current implementation and this version is that > >> now reader is woken up when there is at least one RW packet in rx > >> queue of socket and data is copied to user's buffer, while merged > >> approach wake up user only when whole message is received and kept > >> in queue. New implementation has several advantages: > >> 1) There is no limit for message length. Merged approach requires > >> that length must be smaller than 'peer_buf_alloc', otherwise > >> transmission will stuck. > >> 2) There is no need to keep whole message in queue, thus no > >> 'kmalloc()' memory will be wasted until EOR is received. > >> > >> Also new approach has some feature: as fragments of message > >> are copied until EOR is received, it is possible that part of > >> message will be already in user's buffer, while rest of message > >> still not received. And if user will be interrupted by signal or > >> timeout with part of message in buffer, it will exit receive loop, > >> leaving rest of message in queue. To solve this problem special > >> callback was added to transport: it is called when user was forced > >> to leave exit loop and tells transport to drop any packet until > >> EOR met. > > Sorry about commenting late in the game. I'm a bit lost > > > > > > SOCK_SEQPACKET > > Provides sequenced, reliable, bidirectional, connection-mode transmission paths for records. A record can be sent using one or more output operations and received using one or more input operations, but a single operation never transfers part of more than one record. Record boundaries are visible to the receiver via the MSG_EOR flag. > > > > it's supposed to be reliable - how is it legal to drop packets? > > Sorry, seems i need to rephrase description. "Packet" here means fragment of record(message) at transport > > layer. As this is SEQPACKET mode, receiver could get only whole message or error, so if only several fragments > > of message was copied (if signal received for example) we can't return it to user - it breaks SEQPACKET sense. I think, > > in this case we can drop rest of record's fragments legally. > > > Thank You Would not that violate the reliable property? IIUC it's only ok to return an error if socket gets closed. Just like e.g. TCP ... > > > > > >> When EOR is found, this mode is disabled and normal packet > >> processing started. Note, that when 'drop until EOR' mode is on, > >> incoming packets still inserted in queue, reader will be woken up, > >> tries to copy data, but nothing will be copied until EOR found. > >> It was possible to drain such unneeded packets it rx work without > >> kicking user, but implemented way is simplest. Anyway, i think > >> such cases are rare. > > > >> New test also added - it tries to copy to invalid user's > >> buffer. > >> > >> Arseny Krasnov (16): > >> af_vsock/virtio/vsock: change seqpacket receive logic > >> af_vsock/virtio/vsock: remove 'seqpacket_has_data' callback > >> virtio/vsock: remove 'msg_count' based logic > >> af_vsock/virtio/vsock: add 'seqpacket_drop()' callback > >> virtio/vsock: remove record size limit for SEQPACKET > >> vsock_test: SEQPACKET read to broken buffer > >> > >> drivers/vhost/vsock.c | 2 +- > >> include/linux/virtio_vsock.h | 7 +- > >> include/net/af_vsock.h | 4 +- > >> net/vmw_vsock/af_vsock.c | 44 ++++---- > >> net/vmw_vsock/virtio_transport.c | 2 +- > >> net/vmw_vsock/virtio_transport_common.c | 103 ++++++++----------- > >> net/vmw_vsock/vsock_loopback.c | 2 +- > >> tools/testing/vsock/vsock_test.c | 120 ++++++++++++++++++++++ > >> 8 files changed, 193 insertions(+), 91 deletions(-) > >> > >> v1 -> v2: > >> Patches reordered and reorganized. > >> > >> Signed-off-by: Arseny Krasnov > >> --- > >> cv.txt | 0 > >> 1 file changed, 0 insertions(+), 0 deletions(-) > >> create mode 100644 cv.txt > >> > >> diff --git a/cv.txt b/cv.txt > >> new file mode 100644 > >> index 000000000000..e69de29bb2d1 > >> -- > >> 2.25.1 > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization