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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCFBEC4167B for ; Thu, 30 Nov 2023 13:51:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345694AbjK3Nvc (ORCPT ); Thu, 30 Nov 2023 08:51:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345581AbjK3Nvb (ORCPT ); Thu, 30 Nov 2023 08:51:31 -0500 Received: from mx1.sberdevices.ru (mx2.sberdevices.ru [45.89.224.132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3D63137; Thu, 30 Nov 2023 05:51:34 -0800 (PST) Received: from p-infra-ksmg-sc-msk02 (localhost [127.0.0.1]) by mx1.sberdevices.ru (Postfix) with ESMTP id 66BAF120008; Thu, 30 Nov 2023 16:51:33 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.sberdevices.ru 66BAF120008 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=salutedevices.com; s=mail; t=1701352293; bh=lgDstG8AR2X5fihUSohCw6miMFgwYXoychpQoa6AkGk=; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type:From; b=C1K7xIV45lCyg1A2rsM3Pkar5oj2PIvpUiWMb7hifeyUdUtGCtEt+05hk+m8/M2WS d5phS+D9JlLACnb6Ak+Pbjw9a4FgBJ3HfrWRsHWui+mY7ND0VUfp69H2nE4zJBspZs GryrdWbsuFh0S8cT31VrSaauAuCvzuG1RryXgt98lYIXwD6jb6mX3CUw9DkVhWu4UD vldew2SgqTsMECEw/t63+UbBDCOL9onJoxwuRj/NXFCWTOHjMIcEO2Itr/WLul10IQ u27he/ipy+9sGCbsaz6Ops2CQ/LAdZUQgulgEyBIOTvb2zxiwg19MvPCb8iOdV8BgT TgyAldTFXBbpg== Received: from p-i-exch-sc-m01.sberdevices.ru (p-i-exch-sc-m01.sberdevices.ru [172.16.192.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.sberdevices.ru (Postfix) with ESMTPS; Thu, 30 Nov 2023 16:51:33 +0300 (MSK) Received: from [192.168.0.106] (100.64.160.123) by p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 30 Nov 2023 16:51:32 +0300 Message-ID: <02de8982-ec4a-b3b2-e8e5-1bca28cfc01b@salutedevices.com> Date: Thu, 30 Nov 2023 16:43:34 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH net-next v5 2/3] virtio/vsock: send credit update during setting SO_RCVLOWAT Content-Language: en-US To: "Michael S. Tsirkin" CC: Stefan Hajnoczi , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jason Wang , Bobby Eshleman , , , , , , References: <20231130130840.253733-1-avkrasnov@salutedevices.com> <20231130130840.253733-3-avkrasnov@salutedevices.com> <20231130084044-mutt-send-email-mst@kernel.org> From: Arseniy Krasnov In-Reply-To: <20231130084044-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [100.64.160.123] X-ClientProxiedBy: p-i-exch-sc-m02.sberdevices.ru (172.16.192.103) To p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) X-KSMG-Rule-ID: 10 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Lua-Profiles: 181739 [Nov 30 2023] X-KSMG-AntiSpam-Version: 6.0.0.2 X-KSMG-AntiSpam-Envelope-From: avkrasnov@salutedevices.com X-KSMG-AntiSpam-Rate: 0 X-KSMG-AntiSpam-Status: not_detected X-KSMG-AntiSpam-Method: none X-KSMG-AntiSpam-Auth: dkim=none X-KSMG-AntiSpam-Info: LuaCore: 5 0.3.5 98d108ddd984cca1d7e65e595eac546a62b0144b, {Tracking_from_domain_doesnt_match_to}, 127.0.0.199:7.1.2;p-i-exch-sc-m01.sberdevices.ru:5.0.1,7.1.1;100.64.160.123:7.1.2;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;salutedevices.com:7.1.1, FromAlignment: s, ApMailHostAddress: 100.64.160.123 X-MS-Exchange-Organization-SCL: -1 X-KSMG-AntiSpam-Interceptor-Info: scan successful X-KSMG-AntiPhishing: Clean X-KSMG-LinksScanning: Clean X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 2.0.1.6960, bases: 2023/11/30 11:05:00 #22583687 X-KSMG-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30.11.2023 16:42, Michael S. Tsirkin wrote: > On Thu, Nov 30, 2023 at 04:08:39PM +0300, Arseniy Krasnov wrote: >> Send credit update message when SO_RCVLOWAT is updated and it is bigger >> than number of bytes in rx queue. It is needed, because 'poll()' will >> wait until number of bytes in rx queue will be not smaller than >> SO_RCVLOWAT, so kick sender to send more data. Otherwise mutual hungup >> for tx/rx is possible: sender waits for free space and receiver is >> waiting data in 'poll()'. >> >> Signed-off-by: Arseniy Krasnov >> --- >> Changelog: >> v1 -> v2: >> * Update commit message by removing 'This patch adds XXX' manner. >> * Do not initialize 'send_update' variable - set it directly during >> first usage. >> v3 -> v4: >> * Fit comment in 'virtio_transport_notify_set_rcvlowat()' to 80 chars. >> v4 -> v5: >> * Do not change callbacks order in transport structures. >> >> drivers/vhost/vsock.c | 1 + >> include/linux/virtio_vsock.h | 1 + >> net/vmw_vsock/virtio_transport.c | 1 + >> net/vmw_vsock/virtio_transport_common.c | 27 +++++++++++++++++++++++++ >> net/vmw_vsock/vsock_loopback.c | 1 + >> 5 files changed, 31 insertions(+) >> >> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c >> index f75731396b7e..4146f80db8ac 100644 >> --- a/drivers/vhost/vsock.c >> +++ b/drivers/vhost/vsock.c >> @@ -451,6 +451,7 @@ static struct virtio_transport vhost_transport = { >> .notify_buffer_size = virtio_transport_notify_buffer_size, >> >> .read_skb = virtio_transport_read_skb, >> + .notify_set_rcvlowat = virtio_transport_notify_set_rcvlowat >> }, >> >> .send_pkt = vhost_transport_send_pkt, >> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h >> index ebb3ce63d64d..c82089dee0c8 100644 >> --- a/include/linux/virtio_vsock.h >> +++ b/include/linux/virtio_vsock.h >> @@ -256,4 +256,5 @@ void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit); >> void virtio_transport_deliver_tap_pkt(struct sk_buff *skb); >> int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *list); >> int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t read_actor); >> +int virtio_transport_notify_set_rcvlowat(struct vsock_sock *vsk, int val); >> #endif /* _LINUX_VIRTIO_VSOCK_H */ >> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >> index af5bab1acee1..8007593a3a93 100644 >> --- a/net/vmw_vsock/virtio_transport.c >> +++ b/net/vmw_vsock/virtio_transport.c >> @@ -539,6 +539,7 @@ static struct virtio_transport virtio_transport = { >> .notify_buffer_size = virtio_transport_notify_buffer_size, >> >> .read_skb = virtio_transport_read_skb, >> + .notify_set_rcvlowat = virtio_transport_notify_set_rcvlowat >> }, >> >> .send_pkt = virtio_transport_send_pkt, >> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >> index f6dc896bf44c..1cb556ad4597 100644 >> --- a/net/vmw_vsock/virtio_transport_common.c >> +++ b/net/vmw_vsock/virtio_transport_common.c >> @@ -1684,6 +1684,33 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto >> } >> EXPORT_SYMBOL_GPL(virtio_transport_read_skb); >> >> +int virtio_transport_notify_set_rcvlowat(struct vsock_sock *vsk, int val) >> +{ >> + struct virtio_vsock_sock *vvs = vsk->trans; >> + bool send_update; >> + >> + spin_lock_bh(&vvs->rx_lock); >> + >> + /* If number of available bytes is less than new SO_RCVLOWAT value, >> + * kick sender to send more data, because sender may sleep in its >> + * 'send()' syscall waiting for enough space at our side. >> + */ >> + send_update = vvs->rx_bytes < val; >> + >> + spin_unlock_bh(&vvs->rx_lock); >> + >> + if (send_update) { >> + int err; >> + >> + err = virtio_transport_send_credit_update(vsk); >> + if (err < 0) >> + return err; >> + } >> + >> + return 0; >> +} > > > I find it strange that this will send a credit update > even if nothing changed since this was called previously. > I'm not sure whether this is a problem protocol-wise, > but it certainly was not envisioned when the protocol was > built. WDYT? >From virtio spec I found: It is also valid to send a VIRTIO_VSOCK_OP_CREDIT_UPDATE packet without previously receiving a VIRTIO_VSOCK_OP_CREDIT_REQUEST packet. This allows communicating updates any time a change in buffer space occurs. So I guess there is no limitations to send such type of packet, e.g. it is not required to be a reply for some another packet. Please, correct me if im wrong. Thanks, Arseniy > > >> +EXPORT_SYMBOL_GPL(virtio_transport_notify_set_rcvlowat); >> + >> MODULE_LICENSE("GPL v2"); >> MODULE_AUTHOR("Asias He"); >> MODULE_DESCRIPTION("common code for virtio vsock"); >> diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c >> index 048640167411..9f4b814fbbc7 100644 >> --- a/net/vmw_vsock/vsock_loopback.c >> +++ b/net/vmw_vsock/vsock_loopback.c >> @@ -98,6 +98,7 @@ static struct virtio_transport loopback_transport = { >> .notify_buffer_size = virtio_transport_notify_buffer_size, >> >> .read_skb = virtio_transport_read_skb, >> + .notify_set_rcvlowat = virtio_transport_notify_set_rcvlowat >> }, >> >> .send_pkt = vsock_loopback_send_pkt, >> -- >> 2.25.1 >