From patchwork Thu Dec 28 01:46:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Wei X-Patchwork-Id: 13505548 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68E71EDB for ; Thu, 28 Dec 2023 01:46:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=davidwei.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=davidwei.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=davidwei-uk.20230601.gappssmtp.com header.i=@davidwei-uk.20230601.gappssmtp.com header.b="fJ4eyBee" Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-1d3dee5f534so43853705ad.1 for ; Wed, 27 Dec 2023 17:46:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=davidwei-uk.20230601.gappssmtp.com; s=20230601; t=1703727999; x=1704332799; darn=vger.kernel.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=HS58+UKX3zYzrUWjdlnAGph2pSrC7waS+cUH+Y73puo=; b=fJ4eyBee2IhvMjzYjaluNxfiMMX6fivDgdFEk28pheMXerSaReV72+llUVzjJwO3jO lgeqaStMf9GWIf1NiVaK4EM+vEaBp8Tbt5zsT2fr04MmAGZPo0R8/jkZKX1FxwDL1nE3 DJHuo3DWCj6timqzZfdgUQZDrEIHh2q9NU9bwTsJxFy0Zq8eHVs2HKDcQcHyqyGsoeOh SJaiT3NLneQLMRnZDSDclg/A8ZTZnNhQnEYyvvT1bSrDVQ1ge7xaD8PksNJqemTAqzVq 8vsEro8YE7FreVt2e93IBYjhWLC5Kp7Fo4+TeEJa0G47n3AXv9UgF0z4yc6eYHhEr/7v YKtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703727999; x=1704332799; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=HS58+UKX3zYzrUWjdlnAGph2pSrC7waS+cUH+Y73puo=; b=pdh6giTgZtvUqwB2f3abo4KaHnciKo7GGLaG5G46/zDiPXnCjMlIS+srFoRh5ppd01 vkseuhv3kYh50teEEVbiOVhhn7ROBepbFJL2OtpDNm8Lmc4O4r3cYj0L8/iYHjvaJcMB aSkq/qsDP1KFgvM6+FHDDAIGyAQ0MjeNBOOeYPLW65HY9nhWS46QYJXzSVwNLDCisMQI QrYkl6TYr8AtBoJIXmBvCk1AEojQMLMN6xx018f9Qy7qss2NbWzU94iG6Yav8xXLFftr 1OZaHKkU16cnq9McZgNakTB0il3iZLCzQg2JIjNCHRk9TL8kMHSY3K4fbQYaGBbnpWV0 ZGEA== X-Gm-Message-State: AOJu0Yx/tEbO4tpCbyh4uz6UgBXCbwYHrSk6S1X4kAxY9+8usYNt/YgS kdOCt5eWmFWVxJnSduULTQxuacGzlHALwcJLQo/JtZR3Iok= X-Google-Smtp-Source: AGHT+IFnOA+MNP93s632NzdRvC0WCNfXwdY10gKVyb8pXRHMLOQl8Wj7VCzhtMpDUmfN91AXSabj6w== X-Received: by 2002:a17:903:40cc:b0:1d3:f7ce:c187 with SMTP id t12-20020a17090340cc00b001d3f7cec187mr11372196pld.17.1703727999727; Wed, 27 Dec 2023 17:46:39 -0800 (PST) Received: from localhost (fwdproxy-prn-017.fbsv.net. [2a03:2880:ff:11::face:b00c]) by smtp.gmail.com with ESMTPSA id z20-20020a170902ee1400b001d3a9676973sm12650854plb.111.2023.12.27.17.46.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Dec 2023 17:46:39 -0800 (PST) From: David Wei To: Jakub Kicinski , Jiri Pirko , Sabrina Dubroca , netdev@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Paolo Abeni Subject: [PATCH net-next v5 3/5] netdevsim: forward skbs from one connected port to another Date: Wed, 27 Dec 2023 17:46:31 -0800 Message-Id: <20231228014633.3256862-4-dw@davidwei.uk> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20231228014633.3256862-1-dw@davidwei.uk> References: <20231228014633.3256862-1-dw@davidwei.uk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Forward skbs sent from one netdevsim port to its connected netdevsim port using dev_forward_skb, in a spirit similar to veth. Add a tx_dropped variable to struct netdevsim, tracking the number of skbs that could not be forwarded using dev_forward_skb(). The xmit() function accessing the peer ptr is protected by an RCU read critical section. The rcu_read_lock() is functionally redundant as since v5.0 all softirqs are implicitly RCU read critical sections; but it is useful for human readers. If another CPU is concurrently in nsim_destroy(), then it will first set the peer ptr to NULL. This does not affect any existing readers that dereferenced a non-NULL peer. Then, in unregister_netdevice(), there is a synchronize_rcu() before the netdev is actually unregistered and freed. This ensures that any readers i.e. xmit() that got a non-NULL peer will complete before the netdev is freed. Any readers after the RCU_INIT_POINTER() but before synchronize_rcu() will dereference NULL, making it safe. The codepath to nsim_destroy() and nsim_create() takes both the newly added nsim_dev_list_lock and rtnl_lock. This makes it safe with concurrent calls to linking two netdevsims together. Signed-off-by: David Wei --- drivers/net/netdevsim/netdev.c | 21 ++++++++++++++++++--- drivers/net/netdevsim/netdevsim.h | 1 + 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c index 434322f6a565..0009d0f1243f 100644 --- a/drivers/net/netdevsim/netdev.c +++ b/drivers/net/netdevsim/netdev.c @@ -29,19 +29,34 @@ static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct netdevsim *ns = netdev_priv(dev); + struct netdevsim *peer_ns; + int ret = NETDEV_TX_OK; if (!nsim_ipsec_tx(ns, skb)) goto out; + rcu_read_lock(); + peer_ns = rcu_dereference(ns->peer); + if (!peer_ns) + goto out_stats; + + skb_tx_timestamp(skb); + if (unlikely(dev_forward_skb(peer_ns->netdev, skb) == NET_RX_DROP)) + ret = NET_XMIT_DROP; + +out_stats: + rcu_read_unlock(); u64_stats_update_begin(&ns->syncp); ns->tx_packets++; ns->tx_bytes += skb->len; + if (ret == NET_XMIT_DROP) + ns->tx_dropped++; u64_stats_update_end(&ns->syncp); + return ret; out: dev_kfree_skb(skb); - - return NETDEV_TX_OK; + return ret; } static void nsim_set_rx_mode(struct net_device *dev) @@ -70,6 +85,7 @@ nsim_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) start = u64_stats_fetch_begin(&ns->syncp); stats->tx_bytes = ns->tx_bytes; stats->tx_packets = ns->tx_packets; + stats->tx_dropped = ns->tx_dropped; } while (u64_stats_fetch_retry(&ns->syncp, start)); } @@ -302,7 +318,6 @@ static void nsim_setup(struct net_device *dev) eth_hw_addr_random(dev); dev->tx_queue_len = 0; - dev->flags |= IFF_NOARP; dev->flags &= ~IFF_MULTICAST; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h index 24fc3fbda791..083b1ee7a1a2 100644 --- a/drivers/net/netdevsim/netdevsim.h +++ b/drivers/net/netdevsim/netdevsim.h @@ -98,6 +98,7 @@ struct netdevsim { u64 tx_packets; u64 tx_bytes; + u64 tx_dropped; struct u64_stats_sync syncp; struct nsim_bus_dev *nsim_bus_dev;