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 121ABEA719A for ; Sun, 19 Apr 2026 16:12:03 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 018D840696; Sun, 19 Apr 2026 18:11:20 +0200 (CEST) Received: from mail-oo1-f53.google.com (mail-oo1-f53.google.com [209.85.161.53]) by mails.dpdk.org (Postfix) with ESMTP id F08B540654 for ; Sun, 19 Apr 2026 18:11:16 +0200 (CEST) Received: by mail-oo1-f53.google.com with SMTP id 006d021491bc7-689e6737446so1195964eaf.1 for ; Sun, 19 Apr 2026 09:11:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20251104.gappssmtp.com; s=20251104; t=1776615076; x=1777219876; 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=JddTF/d8ChYYa7K3LDXseSCPFApIjG1jw+34OMmtPTlLI1a4MX98AhcrOBfUxskZvy 1q/i+L3rxa15LHeIVgMV0ICmwlwxtybvirBja6Bv7RSDpgo+N2MJjM4XkDxS5b2FmJSS lYxeA7jw6sx0GnhdHIbZKkd9uh9RaGqBzh7TP4zMb85KgGYi0aUTNggzy5/8qFXkYASa r2dQ9y7snme0pcU9hcqpeUIXK/aUiPOFaTgAgzUyZM/T7gMuEAuQ14Uq7EKYOGB8IkFs 3W+sWBYBGZisIueSSeaSkctPmU64xK+qWqZuAZKsFoPQiumQUSP15ZNmldEU/9G9bmTG CUVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776615076; x=1777219876; 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=tAFdHwE7l/a0aPmxDWlUUw3CNzRNPmXCPu6A85/7gxcYAyXoqNqQ1TDK4ExN5/IPWS /wprM1UBrSWk+xEdnSb5FCmMOJ06f0CvRe8g5Wawg3iVpd3QGYC6tvVvw9QYu02rl5nn iwVcEh8k17d/2rtHaB2tBRhXD/EfG9UwoTxD7AM7tNd+apVEoZbN6Q08VrI1j4IMZTtd 9iiel8p6ClpGygbt8BVArmNn8vxaMfQCnRlqlZ6zZeb8Dt3b75IOng4lyLb/4VH/MxBi jwJpFKgams0UHmIiVqjWbWrxGIba4jkwvoUlNn2FssSIqt9me9X/worDYlJprz7sB/K1 VhYg== X-Gm-Message-State: AOJu0YxkPpmic5HwyI78HMuQdcaU7vF8OWx49A6iomCkr7LgOtniII1O r+ez8PvSKXlYHN3GklNP9MZJVxMZzwWYFY+pd36ezXxYOmSs/KbApftOVS9erhH6n6yoHMCZkB9 xoXPY X-Gm-Gg: AeBDieuw3aIcYETO968Nbky98qN7MSt8aiOwLGZh3+oZCAlDIlUWjXvF0Ph9ZegqrMq NXhDyjV7EoEzW5nrYPsJmyRD3ZubeQdZz1qEQEDvRgtnRrcTQGrI7VjzlwcCbLOpiqd7/VD4P2a NHKvpzTNKj56V9qD/FmrzGc8hvY7qY/63tPZX7m5dT6aFw3N++eLdxx17llu0mWc4B8GgKo0CdD sLTtXZurphNQos6xNdBtwGG2TLSjmBWrM2flEP6FhY2Ai/ecbiGBht1oKWABpD+fF6pOlj+l/2b s/DxRz7J+7cznmYLTq4ujMumA3r8fS8A6VDDPhLrMOM6NO34AK7bGU90WgJ5gO1C97Go9R005L+ +wbNZswdwHfgaxHAOjAL68ZdQ9S7AKTw0QeQIvnOBHrMJYLpPCD3ONfJqp3gvD4N6+t44iUrXDS r3NCZITzMmS63DiH+1LhN0ckUssaqy/vRrvxufQEOxsqc= X-Received: by 2002:a05:6820:1888:b0:67f:ab5d:1748 with SMTP id 006d021491bc7-69462f08433mr5669645eaf.48.1776615076252; Sun, 19 Apr 2026 09:11:16 -0700 (PDT) Received: from phoenix.lan ([104.202.41.210]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-42b930bca47sm5970632fac.7.2026.04.19.09.11.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Apr 2026 09:11:15 -0700 (PDT) From: Stephen Hemminger To: dev@dpdk.org Cc: Stephen Hemminger , stable@dpdk.org, Ferruh Yigit , David Marchand Subject: [PATCH v25 09/24] net/pcap: fix error accounting and backpressure on transmit Date: Sun, 19 Apr 2026 09:09:42 -0700 Message-ID: <20260419161059.205954-10-stephen@networkplumber.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260419161059.205954-1-stephen@networkplumber.org> References: <20260106182823.192350-1-stephen@networkplumber.org> <20260419161059.205954-1-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