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 1462E103A99F for ; Wed, 25 Mar 2026 02:41:16 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 52B3F40E38; Wed, 25 Mar 2026 03:40:35 +0100 (CET) Received: from mail-dy1-f182.google.com (mail-dy1-f182.google.com [74.125.82.182]) by mails.dpdk.org (Postfix) with ESMTP id B026640E16 for ; Wed, 25 Mar 2026 03:40:31 +0100 (CET) Received: by mail-dy1-f182.google.com with SMTP id 5a478bee46e88-2c160cb021cso295641eec.1 for ; Tue, 24 Mar 2026 19:40:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20230601.gappssmtp.com; s=20230601; t=1774406431; x=1775011231; 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=MbKcA/t0AuHQtkfJyYpk9mF5GmMGma00uJ79EG5hXQmm+jfZG9hI7LfIGR3kw4m2sF i7tKw8rM+SMEt3tfOxFXS5TPiLOSXoMsJAK148Oz46MI8xqzOfxzPO+4+cDV4GikfOEA DIZCLSSk/g9EZKiYalt+3QlS8hVmkCxc9/ZWDhzavXU4SfTHZ1lrCySxgk+GLd0oEVCY 8eDWG+XOlXzqv8GqOzlOVWH3FWMArkO+Lzvbs01DlVkEBXEUki2woFNMhbc7PGBEjErq zJpH1F805yuWF+17WyZ+IqAyE+JeZVPOlC6HxvPCxETWLnIAzchuigwjpSsV0TK6EqCz z3aA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774406431; x=1775011231; 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=S1xZlD0b+cy9ZgE+bltYEmIyrXujxO6+IyJb/SLilZb8T1ShjL/TYlsPCKOZEz5t2C bPgvS8ZvR7TXCWOUgbKOpU8A/mwQJE4I04gqZITPjbB+HvfXaochGveStdA5Four/JJj cOSiu4mdP2imAiSxZpMd7yQS2K0aLqgDSm04qs0ihJ/ZxdUQ/WW/i2C/uI8tMOfEU6Id T2a57y/rlgQNPKKL8Y3w3YpE6/CZDEEzXo1Rl0g7JZMgz5a/rbg/68SJA7YYvEx89K8R ya5VWU095cG6PZFMMzaaQcR0F8bx+j8p9a/rfplasoR+rhum/9gcfyi7+iHUCConaQxo bC2g== X-Gm-Message-State: AOJu0YxGwTX/YbHg2CRnOQduK/6aVWMVD5/tll+4/RKFn76ixZOffsSY 9tOSijQdOxE6LaldxrPQVeeFlIOSKiPf4krm4fkmv81Jx7f5L6dCHFcKq68FZwVWhMQBzNCF+wF 1PnuS X-Gm-Gg: ATEYQzyU6wjUFyyxgnBQwgb45RfCWi/LIhjFErWpqK9/huUUQCY2ydLXUyrhRmc/ZNf 1C14EKWVWzNFtoSB6qTxQu8HZcYMX6viewMFJMMdDsc3krKeEyjHKovarY68OX1S/Ioj5xn1Cz2 IpfaycHOMwVURzUMiUqt+w6AEotzM5sYREBm4m4Frl35gIxOw9B26x50WDi9k4TWSQTbIQo+056 wm4t/5qbJrPOwmm5vi0lKrmLnYbE/QvWSIHwNqfsZwCkrdIIrQqCkhx/rBlv2SgMhqDp1sN3slf XFtY9DlFEIFwyTHLiFEYk3+XZWIPaYZUqtHAdz2mOfvARpfqvnqBfokVsmG5OJrMJNze3rPQ9Q4 x7PP6pF+O35MWvOouMJ3GlALwf5dUu8xLJ4MPMovL5NCbQVTV5RCkRXBgZaYeBi+ThxX9yWJhrY kmAX0eu53Ibk5J6TuwhsKEv0d3GTOLNiy6 X-Received: by 2002:a05:7300:dc04:b0:2bd:cfce:4c4b with SMTP id 5a478bee46e88-2c15d32b6acmr784049eec.2.1774406430523; Tue, 24 Mar 2026 19:40:30 -0700 (PDT) Received: from phoenix.lan ([104.202.29.139]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2c10b29b447sm17209452eec.16.2026.03.24.19.40.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2026 19:40:30 -0700 (PDT) From: Stephen Hemminger To: dev@dpdk.org Cc: Stephen Hemminger , stable@dpdk.org, David Marchand , Ferruh Yigit Subject: [PATCH v21 09/25] net/pcap: fix error accounting and backpressure on transmit Date: Tue, 24 Mar 2026 19:37:40 -0700 Message-ID: <20260325024018.1275209-10-stephen@networkplumber.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260325024018.1275209-1-stephen@networkplumber.org> References: <20260106182823.192350-1-stephen@networkplumber.org> <20260325024018.1275209-1-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