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 mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by smtp.lore.kernel.org (Postfix) with ESMTP id C363CF43828 for ; Wed, 15 Apr 2026 14:49:16 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 99E3C40A6C; Wed, 15 Apr 2026 16:48:22 +0200 (CEST) Received: from mail-oi1-f174.google.com (mail-oi1-f174.google.com [209.85.167.174]) by mails.dpdk.org (Postfix) with ESMTP id C127F4069F for ; Wed, 15 Apr 2026 16:48:20 +0200 (CEST) Received: by mail-oi1-f174.google.com with SMTP id 5614622812f47-47018d34159so4995407b6e.2 for ; Wed, 15 Apr 2026 07:48:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20251104.gappssmtp.com; s=20251104; t=1776264500; x=1776869300; darn=dpdk.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=U8qlHnaWL3xA7pIAnsegSiJnseUdbksPPijuwVzzW1s=; b=KCwM8VssYoWNvTor7aG+TvEwKGCc/SdLnomot0GTzABi7rK5J/N8t3GIdE5OjmHc/+ 4RbAKQxkRT8ejS4Xc5YEwKgdGzYIGevLRfvWBQSMqFi9jqFF1ZWPToH9CkkUBl5DA3DV 9cKPvhpTy7a+gVMYleeO7j4oTDtr3/8PRssVWrp9njWhvAK3vPuWB3JJKfJWkTKXnhdK eAl1g2s6IcaCqbCLpArOcKvJJKcf9Kut+Qs3t9OAome8f9LlMjw40qbGVUQPrG27rbHn tkp2liMBLS9QMdjJb9NELdQmnA9uRPryFgWmK9KgjrU4LSY9jgRmVPh9ziLwzTaMvvNc O0+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776264500; x=1776869300; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=U8qlHnaWL3xA7pIAnsegSiJnseUdbksPPijuwVzzW1s=; b=ax227kCACeDv0buqOJyyNBFI3C4/YcAhOtFHFYzvzh265aLx6oBCV/itnVy3cd3cJK C+Q0Z6P3u1e5K07I+s94khgxyNzgYdet06559NU3A3l4jZmWKOOzlZ+V9ou0Otcqaem+ Z7M7HmXSThI3qdqJvkj/Kmfn4tiYl39i3SIiJ4PklJ0IWc/S+y1NIP9KbBJf+aLVJUQ+ HgWF3PBWSkpbjPWUwmPsLPkRwcF10mqWw4f8wk1yz+aXyaCSZL0WXSH2aPN0nlQE1SQo 744QoPuwyroIPy84JCvf22Z8ETCAoF0FYGmfHNj8DNmogHSj4rp30Ms6kftOv6fwwyu1 OqVA== X-Gm-Message-State: AOJu0YzhBOmAOKXDvQj/vdCZG93GEZE90+4ktGOAMj00TCWh4i54WIBS qABA1OFLRq5Tfg1RwGPo3UNth56ehR3gcqcqBPzKxrShhNiR/txFBLCvIDfSKeEFOUABFzz4RCI imjzP X-Gm-Gg: AeBDieuhkr3B0744LMrgcSYshD8IX/3IJNJRspx3AsD8tLDdsNcprcu0q8XUSeTnkcO agNnWL9gaExnWLKna13HNWIaEWnusjY5msuZLpLsEEIwzZchrtrTqtXQdBDIhx8LC4PRMLRzrpA K+9uAaggA+yLZAP6FuY9eUT79wG/mGOlfV4UTY4/QoDVjKhBRRRkz7MnTURO/HJEvMJldkYbM5P knjK65iS5WzlGr1comtn5tY/rFb2l+LlR9zprpSzSEW/FlSlX8jIwwpgHT4/Ye02TFF0KDUKpSK FHF96lNmOxktycax2uNYPa+8njHS9X5d9Tfy4/z8GMFEzfh4QLR+ivIzoFf8Td7wh/lF+UCZfky r1t7DCVnRZjvjK+UhqzARNFimlJYDiotGzdMbfXeRj7IQCE/ioU4t3ZYw1U216ZO7b5ICvzHvdj o1v/VWCAeFoFizkiJK5WMW6qg6AFqkbpxAtceMhbYI6QU= X-Received: by 2002:a05:6808:191b:b0:467:db7f:ab8b with SMTP id 5614622812f47-4789d1503admr11578307b6e.19.1776264500036; Wed, 15 Apr 2026 07:48:20 -0700 (PDT) Received: from phoenix.lan ([104.202.41.210]) by smtp.gmail.com with ESMTPSA id 5614622812f47-4797a53b1fesm945798b6e.16.2026.04.15.07.48.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2026 07:48:19 -0700 (PDT) From: Stephen Hemminger To: dev@dpdk.org Cc: Stephen Hemminger , stable@dpdk.org, Ferruh Yigit , David Marchand Subject: [PATCH v23 09/24] net/pcap: fix error accounting and backpressure on transmit Date: Wed, 15 Apr 2026 07:45:58 -0700 Message-ID: <20260415144717.226161-10-stephen@networkplumber.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260415144717.226161-1-stephen@networkplumber.org> References: <20260106182823.192350-1-stephen@networkplumber.org> <20260415144717.226161-1-stephen@networkplumber.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Fix two problems in eth_pcap_tx(): Oversized multi-segment packets that exceed the bounce buffer are dropped but were not counted as errors. Add err_pkts accounting for these drops. When pcap_sendpacket() fails due to kernel socket backpressure, the remaining unsent packets were counted as TX errors. Since backpressure is transient (EAGAIN/EBUSY/EINTR), break the loop and return the number of packets attempted so the caller retains ownership of the unsent mbufs per tx_burst semantics. Fixes: fbbbf553f268 ("net/pcap: fix concurrent multiseg Tx") Cc: stable@dpdk.org Signed-off-by: Stephen Hemminger --- drivers/net/pcap/pcap_ethdev.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/drivers/net/pcap/pcap_ethdev.c b/drivers/net/pcap/pcap_ethdev.c index 02d5cb591f..ca08b8e342 100644 --- a/drivers/net/pcap/pcap_ethdev.c +++ b/drivers/net/pcap/pcap_ethdev.c @@ -462,7 +462,17 @@ eth_tx_drop(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) } /* - * Callback to handle sending packets through a real NIC. + * Send a burst of packets to a pcap device. + * + * On Linux, pcap_sendpacket() calls send() on a blocking PF_PACKET + * socket with default kernel buffer sizes and no TX ring (PACKET_TX_RING). + * The send() call only blocks when the kernel socket send buffer is full, + * providing limited backpressure. + * + * On error, pcap_sendpacket() returns non-zero and the loop breaks, + * leaving remaining packets unsent. + * + * Bottom line: backpressure is not an error. */ static uint16_t eth_pcap_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) @@ -484,26 +494,27 @@ eth_pcap_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) for (i = 0; i < nb_pkts; i++) { struct rte_mbuf *mbuf = bufs[i]; - size_t len = rte_pktmbuf_pkt_len(mbuf); - int ret; + uint32_t len = rte_pktmbuf_pkt_len(mbuf); + const uint8_t *data; if (unlikely(!rte_pktmbuf_is_contiguous(mbuf) && len > RTE_ETH_PCAP_SNAPSHOT_LEN)) { PMD_LOG(ERR, - "Dropping multi segment PCAP packet. Size (%zd) > max size (%u).", + "Dropping multi segment PCAP packet. Size (%u) > max size (%u).", len, RTE_ETH_PCAP_SNAPSHOT_LEN); + tx_queue->tx_stat.err_pkts++; rte_pktmbuf_free(mbuf); continue; } - /* rte_pktmbuf_read() returns a pointer to the data directly - * in the mbuf (when the mbuf is contiguous) or, otherwise, - * a pointer to temp_data after copying into it. - */ - ret = pcap_sendpacket(pcap, - rte_pktmbuf_read(mbuf, 0, len, temp_data), len); - if (unlikely(ret != 0)) + data = rte_pktmbuf_read(mbuf, 0, len, temp_data); + RTE_ASSERT(data != NULL); + + if (unlikely(pcap_sendpacket(pcap, data, len) != 0)) { + /* Assume failure is backpressure */ + PMD_LOG(ERR, "pcap_sendpacket() failed: %s", pcap_geterr(pcap)); break; + } num_tx++; tx_bytes += len; rte_pktmbuf_free(mbuf); @@ -511,7 +522,6 @@ eth_pcap_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts) tx_queue->tx_stat.pkts += num_tx; tx_queue->tx_stat.bytes += tx_bytes; - tx_queue->tx_stat.err_pkts += i - num_tx; return i; } -- 2.53.0