From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: passt.top; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=X/MoZHmn; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by passt.top (Postfix) with ESMTPS id E228B5A0269 for ; Fri, 27 Mar 2026 18:58:46 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774634325; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SO4EEOXf7yWgAGbu63+ESp8wlaQTSBxQ+k5vke/bZyw=; b=X/MoZHmnwk2ffc0gCNnq/nUIBAYCh8pjeZx06KT246vKWo7rwimv0J9yyVdNBiyhUsVeMh j3u1anbFpJD6h6Z6ZolQofEx96i4fO/Kf6GGta2d8XYYMxcBq3WifUgRtBvmOcVDUqyoKM 2nt8yenTpHIYJFAGdc/dpdX6c2Ol8Pw= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-225-EZXm70u0PRCFMpE6szUxkg-1; Fri, 27 Mar 2026 13:58:44 -0400 X-MC-Unique: EZXm70u0PRCFMpE6szUxkg-1 X-Mimecast-MFC-AGG-ID: EZXm70u0PRCFMpE6szUxkg_1774634323 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6547C19560A2 for ; Fri, 27 Mar 2026 17:58:43 +0000 (UTC) Received: from lenovo-t14s.redhat.com (unknown [10.44.32.96]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6F585180035F; Fri, 27 Mar 2026 17:58:42 +0000 (UTC) From: Laurent Vivier To: passt-dev@passt.top Subject: [PATCH v5 4/8] udp_vu: Move virtqueue management from udp_vu_sock_recv() to its caller Date: Fri, 27 Mar 2026 18:58:30 +0100 Message-ID: <20260327175834.831995-5-lvivier@redhat.com> In-Reply-To: <20260327175834.831995-1-lvivier@redhat.com> References: <20260327175834.831995-1-lvivier@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: uAP3tLmhNjjx-xLpuPlsYM_bXBSle0tf7yz6e5dbbLc_1774634323 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Message-ID-Hash: DZCCDQI3ZDT7MK6TMFXPGHCFIB6GO3VD X-Message-ID-Hash: DZCCDQI3ZDT7MK6TMFXPGHCFIB6GO3VD X-MailFrom: lvivier@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Laurent Vivier X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: udp_vu_sock_recv() currently mixes two concerns: receiving data from the socket and managing virtqueue buffers (collecting, rewinding, releasing). This makes the function harder to reason about and couples socket I/O with virtqueue state. Move all virtqueue operations, vu_collect(), vu_init_elem(), vu_queue_rewind(), vu_set_vnethdr(), and the queue-readiness check, into udp_vu_sock_to_tap(), which is the only caller. This turns udp_vu_sock_recv() into a pure socket receive function that simply reads into the provided iov array and adjusts its length. Signed-off-by: Laurent Vivier --- udp_vu.c | 96 +++++++++++++++++++++++++++++--------------------------- 1 file changed, 49 insertions(+), 47 deletions(-) diff --git a/udp_vu.c b/udp_vu.c index 537e9c92cfa6..90d5cd71bab2 100644 --- a/udp_vu.c +++ b/udp_vu.c @@ -58,45 +58,22 @@ static size_t udp_vu_hdrlen(bool v6) /** * udp_vu_sock_recv() - Receive datagrams from socket into vhost-user buffers - * @c: Execution context - * @vq: virtqueue to use to receive data * @s: Socket to receive from * @v6: Set for IPv6 connections - * @dlen: Size of received data (output) + * @iov_cnt: Number of collected iov in iov_vu (input) + * Number of iov entries used to store the datagram (output) * - * Return: number of iov entries used to store the datagram, 0 if the datagram - * was discarded because the virtqueue is not ready, -1 on error + * Return: size of received data, -1 on error */ -static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s, - bool v6, ssize_t *dlen) +static ssize_t udp_vu_sock_recv(int s, bool v6, size_t *iov_cnt) { - const struct vu_dev *vdev = c->vdev; - int elem_cnt, elem_used, iov_used; struct msghdr msg = { 0 }; - size_t iov_cnt, hdrlen; - - assert(!c->no_udp); - - if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) { - debug("Got UDP packet, but RX virtqueue not usable yet"); - - if (recvmsg(s, &msg, MSG_DONTWAIT) < 0) - debug_perror("Failed to discard datagram"); - - return 0; - } + size_t hdrlen; + ssize_t dlen; /* compute L2 header length */ hdrlen = udp_vu_hdrlen(v6); - elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem), - iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt, - IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL); - if (elem_cnt == 0) - return -1; - - assert((size_t)elem_cnt == iov_cnt); /* one iovec per element */ - /* reserve space for the headers */ assert(iov_vu[0].iov_len >= MAX(hdrlen, ETH_ZLEN + VNET_HLEN)); iov_vu[0].iov_base = (char *)iov_vu[0].iov_base + hdrlen; @@ -104,25 +81,19 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s, /* read data from the socket */ msg.msg_iov = iov_vu; - msg.msg_iovlen = iov_cnt; + msg.msg_iovlen = *iov_cnt; - *dlen = recvmsg(s, &msg, 0); - if (*dlen < 0) { - vu_queue_rewind(vq, elem_cnt); + dlen = recvmsg(s, &msg, 0); + if (dlen < 0) return -1; - } /* restore the pointer to the headers address */ iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen; iov_vu[0].iov_len += hdrlen; - iov_used = vu_pad(iov_vu, iov_cnt, 0, *dlen + hdrlen); - elem_used = iov_used; /* one iovec per element */ + *iov_cnt = vu_pad(iov_vu, *iov_cnt, 0, dlen + hdrlen); - /* release unused buffers */ - vu_queue_rewind(vq, elem_cnt - elem_used); - - return iov_used; + return dlen; } /** @@ -208,21 +179,52 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx) struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE]; int i; + assert(!c->no_udp); + + if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) { + struct msghdr msg = { 0 }; + + debug("Got UDP packet, but RX virtqueue not usable yet"); + + for (i = 0; i < n; i++) { + if (recvmsg(s, &msg, MSG_DONTWAIT) < 0) + debug_perror("Failed to discard datagram"); + } + + return; + } + for (i = 0; i < n; i++) { + unsigned elem_cnt, elem_used; + size_t iov_cnt; ssize_t dlen; - int iov_used; - iov_used = udp_vu_sock_recv(c, vq, s, v6, &dlen); - if (iov_used < 0) + elem_cnt = vu_collect(vdev, vq, elem, ARRAY_SIZE(elem), + iov_vu, ARRAY_SIZE(iov_vu), &iov_cnt, + IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL); + if (elem_cnt == 0) + break; + + assert((size_t)elem_cnt == iov_cnt); /* one iovec per element */ + + dlen = udp_vu_sock_recv(s, v6, &iov_cnt); + if (dlen < 0) { + vu_queue_rewind(vq, iov_cnt); break; + } + + elem_used = iov_cnt; /* one iovec per element */ + + /* release unused buffers */ + vu_queue_rewind(vq, elem_cnt - elem_used); - if (iov_used > 0) { + if (iov_cnt > 0) { udp_vu_prepare(c, toside, dlen); if (*c->pcap) { - udp_vu_csum(toside, iov_used); - pcap_iov(iov_vu, iov_used, VNET_HLEN); + udp_vu_csum(toside, iov_cnt); + pcap_iov(iov_vu, iov_cnt, VNET_HLEN); } - vu_flush(vdev, vq, elem, iov_used); + vu_flush(vdev, vq, elem, iov_cnt); vu_queue_notify(vdev, vq); } } -- 2.53.0