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=h5jKcnaA; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by passt.top (Postfix) with ESMTPS id A80B55A026D for ; Thu, 05 Mar 2026 13:56:54 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772715413; 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; bh=Y1JdCccBm/BIhdozeKx7raQt/kIWRxkcigfT7aw0L2o=; b=h5jKcnaAeSw8SxX3T6ByoFmb4Hft8stYDgoss1W/ZJ2w5HiPV4Zqe1dc+tQ5OAjp1Glv5k zyKLaIWQtdnOv+zUydJYbGB8z1cgCkgvgmFTye95RNs4g1EXet2Pg4ard5+XlavJXzGx/s U5NPyrZOXV6kwrzDlhcRMghruJT2RbQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-632-XLvnWkkeNKmPcR-Grp6cjA-1; Thu, 05 Mar 2026 07:56:52 -0500 X-MC-Unique: XLvnWkkeNKmPcR-Grp6cjA-1 X-Mimecast-MFC-AGG-ID: XLvnWkkeNKmPcR-Grp6cjA_1772715411 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 67D5C180035D for ; Thu, 5 Mar 2026 12:56:51 +0000 (UTC) Received: from lenovo-t14s.redhat.com (unknown [10.44.32.107]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6C18D180049D; Thu, 5 Mar 2026 12:56:50 +0000 (UTC) From: Laurent Vivier To: passt-dev@passt.top Subject: [PATCH v3] iov: Add iov_truncate() helper and use it in vu handlers Date: Thu, 5 Mar 2026 13:56:48 +0100 Message-ID: <20260305125648.3720714-1-lvivier@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: gZImmk7FINp1dnWUoNKtEliQr9Xgs26ACDPibP9iLeU_1772715411 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Message-ID-Hash: TWXMZGCVUMT43KW6TWINFCN74OIVKCGL X-Message-ID-Hash: TWXMZGCVUMT43KW6TWINFCN74OIVKCGL 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: Add a generic iov_truncate() function that truncates an IO vector to a given number of bytes, returning the number of iov entries that contain data after truncation. Use it in udp_vu_sock_recv() and tcp_vu_sock_recv() to replace the open-coded truncation logic that adjusted iov entries after recvmsg(). Also convert the direct iov_len assignment in tcp_vu_send_flag() to use iov_truncate() for consistency. Signed-off-by: Laurent Vivier --- Notes: v3: use in tcp_vu_send_flag() too v2: use iov_truncate() in udp_vu_sock_recv() too iov.c | 22 ++++++++++++++++++++++ iov.h | 1 + tcp_vu.c | 14 +++----------- udp_vu.c | 12 +++--------- 4 files changed, 29 insertions(+), 20 deletions(-) diff --git a/iov.c b/iov.c index ad726daa4cd8..31a3f5bc29e5 100644 --- a/iov.c +++ b/iov.c @@ -147,6 +147,28 @@ size_t iov_size(const struct iovec *iov, size_t iov_cnt) return len; } +/** + * iov_truncate() - Truncate an IO vector to a given number of bytes + * @iov: IO vector (modified) + * @iov_cnt: Number of entries in @iov + * @size: Total number of bytes to keep + * + * Return: number of iov entries that contain data after truncation + */ +size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size) +{ + size_t i, offset; + + i = iov_skip_bytes(iov, iov_cnt, size, &offset); + + if (i < iov_cnt) { + iov[i].iov_len = offset; + i += !!offset; + } + + return i; +} + /** * iov_tail_prune() - Remove any unneeded buffers from an IOV tail * @tail: IO vector tail (modified) diff --git a/iov.h b/iov.h index d1ab91a94e22..b4e50b0fca5a 100644 --- a/iov.h +++ b/iov.h @@ -29,6 +29,7 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt, size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt, size_t offset, void *buf, size_t bytes); size_t iov_size(const struct iovec *iov, size_t iov_cnt); +size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size); /* * DOC: Theory of Operation, struct iov_tail diff --git a/tcp_vu.c b/tcp_vu.c index 88be232dca66..8ca4170f13f6 100644 --- a/tcp_vu.c +++ b/tcp_vu.c @@ -131,7 +131,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) return ret; } - flags_elem[0].in_sg[0].iov_len = hdrlen + optlen; + iov_truncate(&flags_iov[0], 1, hdrlen + optlen); payload = IOV_TAIL(flags_elem[0].in_sg, 1, hdrlen); if (flags & KEEPALIVE) @@ -192,9 +192,9 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, struct msghdr mh_sock = { 0 }; uint16_t mss = MSS_GET(conn); int s = conn->sock; - ssize_t ret, len; size_t hdrlen; int elem_cnt; + ssize_t ret; int i; *iov_cnt = 0; @@ -247,15 +247,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, ret -= already_sent; /* adjust iov number and length of the last iov */ - len = ret; - for (i = 0; len && i < elem_cnt; i++) { - struct iovec *iov = &elem[i].in_sg[0]; - - if (iov->iov_len > (size_t)len) - iov->iov_len = len; - - len -= iov->iov_len; - } + i = iov_truncate(&iov_vu[DISCARD_IOV_NUM], elem_cnt, ret); /* adjust head count */ while (*head_cnt > 0 && head[*head_cnt - 1] >= i) diff --git a/udp_vu.c b/udp_vu.c index 3520f89e5671..5effca777e0a 100644 --- a/udp_vu.c +++ b/udp_vu.c @@ -71,9 +71,9 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s, bool v6, ssize_t *dlen) { const struct vu_dev *vdev = c->vdev; - int iov_cnt, idx, iov_used; - size_t off, hdrlen, l2len; struct msghdr msg = { 0 }; + int iov_cnt, iov_used; + size_t hdrlen, l2len; ASSERT(!c->no_udp); @@ -115,13 +115,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s, iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen; iov_vu[0].iov_len += hdrlen; - /* count the numbers of buffer filled by recvmsg() */ - idx = iov_skip_bytes(iov_vu, iov_cnt, *dlen + hdrlen, &off); - - /* adjust last iov length */ - if (idx < iov_cnt) - iov_vu[idx].iov_len = off; - iov_used = idx + !!off; + iov_used = iov_truncate(iov_vu, iov_cnt, *dlen + hdrlen); /* pad frame to 60 bytes: first buffer is at least ETH_ZLEN long */ l2len = *dlen + hdrlen - VNET_HLEN; -- 2.53.0