From patchwork Wed Dec 6 03:11:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Willem de Bruijn X-Patchwork-Id: 845019 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="Y5c7BD1Y"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3ys3Yf6Vzvz9ryv for ; Wed, 6 Dec 2017 14:11:50 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754594AbdLFDLs (ORCPT ); Tue, 5 Dec 2017 22:11:48 -0500 Received: from mail-yb0-f195.google.com ([209.85.213.195]:43790 "EHLO mail-yb0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754448AbdLFDLq (ORCPT ); Tue, 5 Dec 2017 22:11:46 -0500 Received: by mail-yb0-f195.google.com with SMTP id i206so1033026ybc.10 for ; Tue, 05 Dec 2017 19:11:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=ZYZx+OdXB+figU0EUieo++RlWW6nqt4fJI2JW+xbTis=; b=Y5c7BD1Y5umOsbbH1nVXKF3PcYNszQ6h/AInd5Vp+pdvIMVN9moJhLHMgKf/0B5lRK QQXUTjIuCpa1k5DxR+J13UntUSDNy8oJnji9wqbIh+LZCp2c0KUw3G0b2tmvMWa/baEP VGgR789HpPKskMFydbWNP3PoYRqAKJUMoVmTbNNSeS1d7H3UrWJoByN/JE+ik7+dbXBF /iMQEClNSm/Wjv/YbI9oURmutqOrbGZgDRmQadJallt+wRxKs582SHMkpDobtRJIwB5T 5Wx92aXGrV735d8dyqej/LcEifxE4jxlD/yPH0JWeUeCV6TJIt2MR54qWW5WA2I3BnPE uaxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=ZYZx+OdXB+figU0EUieo++RlWW6nqt4fJI2JW+xbTis=; b=P+gkuvsFeFPIFIXAqcayBph1fmnMheCecM4R0W/XhNP4uSIGoL29S+RnXJZoRTcx5e EpU0z2zx0Sfx9lelIY/H4F/F6GmqdJ3+tARcFMm6S5IZuqBqpOBlMRWEDQmYs/IEw5Yl kwuC3eQ1yoaTfaVM47BzZQLJod5ZU/u9h5B+lpZGxcR/CdT0MdNVO6womFgFddJ73UKS FUixvT+mdLmF1Kr31Y9rP4BLxSeBh9JNaXC3z46lUnDbjm9CYRl9unXT6Tm1Vo/WOw1Y FXfJlPdjSycQQiNAx58xE7V2JLpwSP5P63Jsik+DHFl+L9979pCW4tEFCdCPO4fw5Acs HSFA== X-Gm-Message-State: AJaThX7+bBsne/sB2Mra5gfBOeF/eIR/SFa6T+2Wi1Ge/NMTjWlkmtVl jgwVEOpZCjmhvIOtr6w9lU8peQlv X-Google-Smtp-Source: AGs4zMYa5iipAVN77/tK2woXPds4dC6DmDEkk3q9cWImUMPa6HJiJEg3i67y5AWWELGXuNMdLf2aNg== X-Received: by 10.37.172.132 with SMTP id x4mr13923254ybi.392.1512529905148; Tue, 05 Dec 2017 19:11:45 -0800 (PST) Received: from willemb1.nyc.corp.google.com ([100.101.212.246]) by smtp.gmail.com with ESMTPSA id l21sm864251ywc.34.2017.12.05.19.11.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 05 Dec 2017 19:11:44 -0800 (PST) From: Willem de Bruijn To: netdev@vger.kernel.org Cc: jasowang@redhat.com, davem@davemloft.net, Willem de Bruijn Subject: [PATCH net-next] tun: avoid unnecessary READ_ONCE in tun_net_xmit Date: Tue, 5 Dec 2017 22:11:17 -0500 Message-Id: <20171206031117.86588-1-willemdebruijn.kernel@gmail.com> X-Mailer: git-send-email 2.15.1.424.g9478a66081-goog Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Willem de Bruijn The statement no longer serves a purpose. Commit fa35864e0bb7 ("tuntap: Fix for a race in accessing numqueues") added the ACCESS_ONCE to avoid a race condition with skb_queue_len. Commit 436accebb530 ("tuntap: remove unnecessary sk_receive_queue length check during xmit") removed the affected skb_queue_len check. Commit 96f84061620c ("tun: add eBPF based queue selection method") split the function, reading the field a second time in the callee. The temp variable is now only read once, so just remove it. Signed-off-by: Willem de Bruijn Acked-by: Jason Wang --- drivers/net/tun.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 787cc35ef89b..c2ad8f3858d1 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -990,14 +990,12 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) struct tun_struct *tun = netdev_priv(dev); int txq = skb->queue_mapping; struct tun_file *tfile; - u32 numqueues = 0; rcu_read_lock(); tfile = rcu_dereference(tun->tfiles[txq]); - numqueues = READ_ONCE(tun->numqueues); /* Drop packet if interface is not attached */ - if (txq >= numqueues) + if (txq >= tun->numqueues) goto drop; if (!rcu_dereference(tun->steering_prog))