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 92AF1F9D0DA for ; Tue, 14 Apr 2026 16:11:20 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 942AC40689; Tue, 14 Apr 2026 18:10:28 +0200 (CEST) Received: from mail-oi1-f172.google.com (mail-oi1-f172.google.com [209.85.167.172]) by mails.dpdk.org (Postfix) with ESMTP id C67FB40684 for ; Tue, 14 Apr 2026 18:10:25 +0200 (CEST) Received: by mail-oi1-f172.google.com with SMTP id 5614622812f47-4648447e29bso1651137b6e.0 for ; Tue, 14 Apr 2026 09:10:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20251104.gappssmtp.com; s=20251104; t=1776183025; x=1776787825; 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=gtaFhdZkLIAEHLd0zRLhNnVUG2SF8PIImY0KvvxG1OlRO+P9Tgsffj5us8DzaopYiE g2VZgK8JN4UJqavIVwTFUUHD+CkFGSC8Hzz7ykghq14syNckVMAP5ZMG27rr5pnBtXW1 GF4M7urO7Qs1G0hPN/y/MctVKTHaW2RwRLcBCOF0IaebWPCo/Pgc0LQDdYRfkLkjeuvS rDuxLS+GyL9/2b+NTxM0lYS7Bu7e4N5yHSJibu/0o7vciEGhDMWeBSMhtCfftEiR7W80 iUHY6KTx18iJXX5ZkTngRk5lOhyEBPqtmZFk/HrvclTOjgn2PM1qwzu225a6bG+/BSAu AdDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776183025; x=1776787825; 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=qLp3DdwUrwnnRyQLdrCOIHwIFJnmw03U2QKqHWWtra9TC/Lsm315jPlhQMxCf8cbeL 8UKVrc09OaXeUsI4Z2MWB0r3G7iiLt+bB+TD1GE5I6tKRkaUZTaBl4lT4yWqUTSavOiu Q9mvOOTqgP0ZysKJiHTDcztAUMCM1nWaBLb7Au2298b6PTejmhF1RsgKQ1e18h8vqAZQ wBWWyLVHJ/fYe/4PZJQ2XG5zPXJhVPg23ahMgrAk4xKKEQUgb5+gzKtPUV24fU6FoVHJ oOQyw4Qo47xq2IbGHoX+GKY7GTJbJ+nXYIwMKB4KlN/WFqxrpfbcplCXH3l0/tDURZSw MiCg== X-Gm-Message-State: AOJu0Yw2zfhW81h39+YhegJMM/R/pjyykGcCe3EPLFmGamLaalRoqS7y KFQji8lpniUoDFki496Eg42jpMyWJkDz2UmpoNJqZKhm27N8ZlpVzkZbr1zNaL79FBHOKTI+UKT nMGy3 X-Gm-Gg: AeBDies0hWXO2y2RwTXw4hokhOrbspAkG8OlWlVuKFvQZDoHwT9ek5YS72MAJLnyib+ VGG1P5hBIy6BV4ACO7vNz1VpZ2csjYKZNEWxUK5Bspw/G7eyk6UdkBIdP21UwFyBX1FtPGBucSj uJNwC13gC/GxIocsbIioNIv5LtiiZXS5yo2m0ZBLbdURrTVBRhOKqe1eq/I/4J97bJifNOZBaEq 3FqtsAN2VDSDHZmBX5zP9pmYesBVwjexhQblD6h85fQl9bZpM/WwXiu+jbPJ3t5Vkg7Zq/dioVj mDYjlWFdisVruDh10rpScUCPq8ShmdGL6iUX4GDY0nYJN0aQ5HAxL53FQvBYNZhPM1nmhJvQKbZ siDZkRJIQfDb8WO+r9094mf/YIZUPw9sNUIuLSq2GnY3c71DnQ1MAZbXB5zH6KpavUOG3y6w7er X2TEbB83AU9y8O0e6lQ6ZGok1du73tkDA0/s1BT51zlSY= X-Received: by 2002:a05:6808:192a:b0:45c:8f03:1e18 with SMTP id 5614622812f47-4789f40f64fmr8895794b6e.44.1776183024969; Tue, 14 Apr 2026 09:10:24 -0700 (PDT) Received: from phoenix.lan ([104.202.41.210]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-423dd396960sm11809554fac.2.2026.04.14.09.10.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 09:10:24 -0700 (PDT) From: Stephen Hemminger To: dev@dpdk.org Cc: Stephen Hemminger , stable@dpdk.org, David Marchand , Ferruh Yigit Subject: [PATCH v22 09/24] net/pcap: fix error accounting and backpressure on transmit Date: Tue, 14 Apr 2026 09:08:00 -0700 Message-ID: <20260414161011.756101-10-stephen@networkplumber.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260414161011.756101-1-stephen@networkplumber.org> References: <20260106182823.192350-1-stephen@networkplumber.org> <20260414161011.756101-1-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