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(p200300ea8f2328008d7e0efd393d7a36.dip0.t-ipconnect.de. [2003:ea:8f23:2800:8d7e:efd:393d:7a36]) by smtp.googlemail.com with ESMTPSA id v12sm752195wro.72.2020.11.05.23.48.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Nov 2020 23:48:53 -0800 (PST) Subject: Re: [PATCH net-next v2 03/10] tun: switch to net core provided statistics counters 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> From: Heiner Kallweit Message-ID: Date: Fri, 6 Nov 2020 08:48:48 +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: <20201105171446.5f78f1a6@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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.