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(p200300ea8f2328008d7e0efd393d7a36.dip0.t-ipconnect.de. [2003:ea:8f23:2800:8d7e:efd:393d:7a36]) by smtp.googlemail.com with ESMTPSA id o20sm383127eja.34.2020.11.06.00.27.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Nov 2020 00:27:51 -0800 (PST) Subject: Re: [PATCH net-next v2 03/10] tun: switch to net core provided statistics counters From: Heiner Kallweit To: Jakub Kicinski , Willem de Bruijn Cc: David Miller , Alexey Kuznetsov , Hideaki YOSHIFUJI , Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , Russell King , Pablo Neira Ayuso , Harald Welte , "Jason A. Donenfeld" , Herbert Xu , "netdev@vger.kernel.org" , osmocom-net-gprs@lists.osmocom.org, wireguard@lists.zx2c4.com, Steffen Klassert References: <059fcb95-fba8-673e-0cd6-fb26e8ed4861@gmail.com> <30fd49be-f467-95f5-9586-fec9fbde8e48@gmail.com> <20201105171446.5f78f1a6@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Message-ID: Date: Fri, 6 Nov 2020 09:27:45 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Mon, 09 Nov 2020 23:40:12 +0100 X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" On 06.11.2020 08:48, Heiner Kallweit wrote: > On 06.11.2020 02:14, Jakub Kicinski wrote: >> On Wed, 4 Nov 2020 15:25:24 +0100 Heiner Kallweit wrote: >>> @@ -1066,7 +1054,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) >>> return NETDEV_TX_OK; >>> >>> drop: >>> - this_cpu_inc(tun->pcpu_stats->tx_dropped); >>> + dev->stats.tx_dropped++; >>> skb_tx_error(skb); >>> kfree_skb(skb); >>> rcu_read_unlock(); >> >> This is no longer atomic. Multiple CPUs may try to update it at the >> same time. >> >> Do you know what the story on dev->rx_dropped is? The kdoc says drivers >> are not supposed to use it but: >> >> drivers/net/ipvlan/ipvlan_core.c: atomic_long_inc(&skb->dev->rx_dropped); >> drivers/net/macvlan.c: atomic_long_inc(&skb->dev->rx_dropped); >> drivers/net/vxlan.c: atomic_long_inc(&vxlan->dev->rx_dropped); >> >> Maybe tun can use it, too? >> > Thanks, yes that should be possible. Here we speak about tx_dropped, > but AFAICS the same applies as for rx_dropped. Will change it accordingly > in a v3. > For rx_dropped and tx_dropped it's easy, however tun also has a per-cpu counter for rx_frame_errors that is incremented if virtio_net_hdr_to_skb() fails. Not sure how to deal best with this one.