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=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 D3294C48BDF for ; Fri, 18 Jun 2021 16:27:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B5741613E9 for ; Fri, 18 Jun 2021 16:27:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235887AbhFRQ3N (ORCPT ); Fri, 18 Jun 2021 12:29:13 -0400 Received: from mx12.kaspersky-labs.com ([91.103.66.155]:45597 "EHLO mx12.kaspersky-labs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234001AbhFRQ3H (ORCPT ); Fri, 18 Jun 2021 12:29:07 -0400 Received: from relay12.kaspersky-labs.com (unknown [127.0.0.10]) by relay12.kaspersky-labs.com (Postfix) with ESMTP id 8702976954; Fri, 18 Jun 2021 19:26:52 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kaspersky.com; s=mail202102; t=1624033612; bh=iQmltOvrHzvEY/ZPm+V981Olell4SUkDQ4jPxSiWNMY=; h=Subject:To:From:Message-ID:Date:MIME-Version:Content-Type; b=R2Mpqp5u+torzDWgAgQxzxrOxBjrjC6c+zgyQrdYRTfyMW1EUzTSiBq7taNUyGy2D PuiCW68X0LnnhVbSpKoMNirzjoWUI4/kFvpLJySB16WEyPhQVBN9OTj+pT3yQkszFF SvIQ3uH+8pyc/MSrGiyvJqXcxpgXH4Lq6DU6Op2GvRlUm37kEhMM1jD2o3SP3t8K9n 1UkcZvGerWxOCENvIrGRW28bPP/fEwIm25IshGQw+eaoLlfCZbk+lmk21hxD0n8rey s7BOhCd9/IDHrzzc5w5oi4yVOq6jf1tQOz3o1RVVbTFnU9LrfUAlUFCXfHdy3D5hER hEKEi5oVUS9cw== Received: from mail-hq2.kaspersky.com (unknown [91.103.66.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (Client CN "mail-hq2.kaspersky.com", Issuer "Kaspersky MailRelays CA G3" (verified OK)) by mailhub12.kaspersky-labs.com (Postfix) with ESMTPS id C23077694F; Fri, 18 Jun 2021 19:26:51 +0300 (MSK) Received: from [10.16.171.77] (10.64.64.121) by hqmailmbx3.avp.ru (10.64.67.243) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.14; Fri, 18 Jun 2021 19:26:50 +0300 Subject: Re: [MASSMAIL KLMS] Re: [PATCH v11 11/18] virtio/vsock: dequeue callback for SOCK_SEQPACKET To: Stefano Garzarella CC: Stefan Hajnoczi , "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Norbert Slusarek , Andra Paraschiv , Colin Ian King , "kvm@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "oxffffaa@gmail.com" References: <20210611110744.3650456-1-arseny.krasnov@kaspersky.com> <20210611111241.3652274-1-arseny.krasnov@kaspersky.com> <20210618134423.mksgnbmchmow4sgh@steredhat.lan> <20210618155555.j5p4v6j5gk2dboj3@steredhat.lan> <650673dc-8b29-657e-5bbd-2cc974628ec9@kaspersky.com> <20210618162509.yppkajmvcbzvidy4@steredhat.lan> From: Arseny Krasnov Message-ID: <31f58b17-02e6-4246-5ad8-7e8d7892ecb7@kaspersky.com> Date: Fri, 18 Jun 2021 19:26:49 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210618162509.yppkajmvcbzvidy4@steredhat.lan> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.64.64.121] X-ClientProxiedBy: hqmailmbx2.avp.ru (10.64.67.242) To hqmailmbx3.avp.ru (10.64.67.243) X-KSE-ServerInfo: hqmailmbx3.avp.ru, 9 X-KSE-AntiSpam-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.20, Database issued on: 06/18/2021 16:10:37 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 0 X-KSE-AntiSpam-Info: Lua profiles 164483 [Jun 18 2021] X-KSE-AntiSpam-Info: Version: 5.9.20.0 X-KSE-AntiSpam-Info: Envelope from: arseny.krasnov@kaspersky.com X-KSE-AntiSpam-Info: LuaCore: 448 448 71fb1b37213ce9a885768d4012c46ac449c77b17 X-KSE-AntiSpam-Info: {Tracking_uf_ne_domains} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: kaspersky.com:7.1.1;lore.kernel.org:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;127.0.0.199:7.1.2 X-KSE-AntiSpam-Info: Rate: 0 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Deterministic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 06/18/2021 16:12:00 X-KSE-AttachmentFiltering-Interceptor-Info: no applicable attachment filtering rules found X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean, bases: 18.06.2021 12:17:00 X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit X-KSE-AttachmentFiltering-Interceptor-Info: no applicable attachment filtering rules found X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit X-KLMS-Rule-ID: 52 X-KLMS-Message-Action: clean X-KLMS-AntiSpam-Status: not scanned, disabled by settings X-KLMS-AntiSpam-Interceptor-Info: not scanned X-KLMS-AntiPhishing: Clean, bases: 2021/06/18 14:20:00 X-KLMS-AntiVirus: Kaspersky Security for Linux Mail Server, version 8.0.3.30, bases: 2021/06/18 12:17:00 #16756757 X-KLMS-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18.06.2021 19:25, Stefano Garzarella wrote: > On Fri, Jun 18, 2021 at 07:08:30PM +0300, Arseny Krasnov wrote: >> On 18.06.2021 18:55, Stefano Garzarella wrote: >>> On Fri, Jun 18, 2021 at 06:04:37PM +0300, Arseny Krasnov wrote: >>>> On 18.06.2021 16:44, Stefano Garzarella wrote: >>>>> Hi Arseny, >>>>> the series looks great, I have just a question below about >>>>> seqpacket_dequeue. >>>>> >>>>> I also sent a couple a simple fixes, it would be great if you can review >>>>> them: >>>>> https://lore.kernel.org/netdev/20210618133526.300347-1-sgarzare@redhat.com/ >>>>> >>>>> >>>>> On Fri, Jun 11, 2021 at 02:12:38PM +0300, Arseny Krasnov wrote: >>>>>> Callback fetches RW packets from rx queue of socket until whole record >>>>>> is copied(if user's buffer is full, user is not woken up). This is done >>>>>> to not stall sender, because if we wake up user and it leaves syscall, >>>>>> nobody will send credit update for rest of record, and sender will wait >>>>>> for next enter of read syscall at receiver's side. So if user buffer is >>>>>> full, we just send credit update and drop data. >>>>>> >>>>>> Signed-off-by: Arseny Krasnov >>>>>> --- >>>>>> v10 -> v11: >>>>>> 1) 'msg_count' field added to count current number of EORs. >>>>>> 2) 'msg_ready' argument removed from callback. >>>>>> 3) If 'memcpy_to_msg()' failed during copy loop, there will be >>>>>> no next attempts to copy data, rest of record will be freed. >>>>>> >>>>>> include/linux/virtio_vsock.h | 5 ++ >>>>>> net/vmw_vsock/virtio_transport_common.c | 84 +++++++++++++++++++++++++ >>>>>> 2 files changed, 89 insertions(+) >>>>>> >>>>>> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h >>>>>> index dc636b727179..1d9a302cb91d 100644 >>>>>> --- a/include/linux/virtio_vsock.h >>>>>> +++ b/include/linux/virtio_vsock.h >>>>>> @@ -36,6 +36,7 @@ struct virtio_vsock_sock { >>>>>> u32 rx_bytes; >>>>>> u32 buf_alloc; >>>>>> struct list_head rx_queue; >>>>>> + u32 msg_count; >>>>>> }; >>>>>> >>>>>> struct virtio_vsock_pkt { >>>>>> @@ -80,6 +81,10 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk, >>>>>> struct msghdr *msg, >>>>>> size_t len, int flags); >>>>>> >>>>>> +ssize_t >>>>>> +virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk, >>>>>> + struct msghdr *msg, >>>>>> + int flags); >>>>>> s64 virtio_transport_stream_has_data(struct vsock_sock *vsk); >>>>>> s64 virtio_transport_stream_has_space(struct vsock_sock *vsk); >>>>>> >>>>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >>>>>> index ad0d34d41444..1e1df19ec164 100644 >>>>>> --- a/net/vmw_vsock/virtio_transport_common.c >>>>>> +++ b/net/vmw_vsock/virtio_transport_common.c >>>>>> @@ -393,6 +393,78 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, >>>>>> return err; >>>>>> } >>>>>> >>>>>> +static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk, >>>>>> + struct msghdr *msg, >>>>>> + int flags) >>>>>> +{ >>>>>> + struct virtio_vsock_sock *vvs = vsk->trans; >>>>>> + struct virtio_vsock_pkt *pkt; >>>>>> + int dequeued_len = 0; >>>>>> + size_t user_buf_len = msg_data_left(msg); >>>>>> + bool copy_failed = false; >>>>>> + bool msg_ready = false; >>>>>> + >>>>>> + spin_lock_bh(&vvs->rx_lock); >>>>>> + >>>>>> + if (vvs->msg_count == 0) { >>>>>> + spin_unlock_bh(&vvs->rx_lock); >>>>>> + return 0; >>>>>> + } >>>>>> + >>>>>> + while (!msg_ready) { >>>>>> + pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list); >>>>>> + >>>>>> + if (!copy_failed) { >>>>>> + size_t pkt_len; >>>>>> + size_t bytes_to_copy; >>>>>> + >>>>>> + pkt_len = (size_t)le32_to_cpu(pkt->hdr.len); >>>>>> + bytes_to_copy = min(user_buf_len, pkt_len); >>>>>> + >>>>>> + if (bytes_to_copy) { >>>>>> + int err; >>>>>> + >>>>>> + /* sk_lock is held by caller so no one else can dequeue. >>>>>> + * Unlock rx_lock since memcpy_to_msg() may sleep. >>>>>> + */ >>>>>> + spin_unlock_bh(&vvs->rx_lock); >>>>>> + >>>>>> + err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy); >>>>>> + if (err) { >>>>>> + /* Copy of message failed, set flag to skip >>>>>> + * copy path for rest of fragments. Rest of >>>>>> + * fragments will be freed without copy. >>>>>> + */ >>>>>> + copy_failed = true; >>>>>> + dequeued_len = err; >>>>> If we fail to copy the message we will discard the entire packet. >>>>> Is it acceptable for the user point of view, or we should leave the >>>>> packet in the queue and the user can retry, maybe with a different >>>>> buffer? >>>>> >>>>> Then we can remove the packets only when we successfully copied all the >>>>> fragments. >>>>> >>>>> I'm not sure make sense, maybe better to check also other >>>>> implementations :-) >>>>> >>>>> Thanks, >>>>> Stefano >>>> Understand, i'll check it on weekend, anyway I think it is >>>> not critical for implementation. >>> Yep, I agree. >>> >>>> I have another question: may be it is useful to research for >>>> approach where packets are not queued until whole message >>>> is received, but copied to user's buffer thus freeing memory. >>>> (like previous implementation, of course with solution of problem >>>> where part of message still in queue, while reader was woken >>>> by timeout or signal). >>>> >>>> I think it is better, because  in current version, sender may set >>>> 'peer_alloc_buf' to  for example 1MB, so at receiver we get >>>> 1MB of 'kmalloc()' memory allocated, while having user's buffer >>>> to copy data there or drop it(if user's buffer is full). This way >>>> won't change spec(e.g. no message id or SEQ_BEGIN will be added). >>>> >>>> What do You think? >>> Yep, I see your point and it would be great, but I think the main issues >>> to fix is how to handle a signal while we are waiting other fragments >>> since the other peer can take unspecified time to send them. >> What about transport callback, something like 'seqpacket_drain()' or >> >> 'seqpacket_drop_curr()' - when we got signal or timeout, notify transport >> >> to drop current message. In virtio case this will set special flag in transport, >> >> so on next dequeue, this flag is checked and if it is set - we drop all packets >> >> until EOR found. Then we can copy untouched new record. >> > But in this way, we will lose the entire message. > > Is it acceptable for seqpacket? > > Stefano Hm, i'll check it. At least for unix domain sockets - it supports SEQPACKET > >