From patchwork Sun Jan 26 03:58:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Fastabend X-Patchwork-Id: 1229326 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) 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; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=b5xE6ckT; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 484zfJ6vCwz9sP3 for ; Sun, 26 Jan 2020 14:59:36 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729163AbgAZD7e (ORCPT ); Sat, 25 Jan 2020 22:59:34 -0500 Received: from mail-pj1-f67.google.com ([209.85.216.67]:36582 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728842AbgAZD7e (ORCPT ); Sat, 25 Jan 2020 22:59:34 -0500 Received: by mail-pj1-f67.google.com with SMTP id gv17so1670902pjb.1; Sat, 25 Jan 2020 19:59:34 -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:in-reply-to:references; bh=6ApWfuJ0D0g3QrelwnDPlSG8OOKZaWuA97rVS5nYc4w=; b=b5xE6ckT9q7fSwYL8kV8uFXEWZvFzT+xtwqoUiQ8iosIvkKb9R0wtLynHYpiRMTTZw 7LvHDc8INM/jI3yS4RoqcEFizA1kwmxSxZU8a6wlzEQmilrFIB7lV/vqJ9yQHFGQwQuh CXvxdqic5v7eikaP2Te9y93lV4FMUDmqBAwcgC6fjScQlMi4+8s0k/h9ED2z01J/mBM8 hJud0dEi5ff3b9DLOSIWzrjiTl6uz8GRcMqV0WChmfzrmrPoz+QBTd6c2avuhuQ8qiR4 sYqTLsbgT6ss+9AQAO9KZi2QPPkxw2kJshrsjxNS7kCrVy7WuD4zhYsrhP3nJhNlVeEP SlGQ== 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:in-reply-to :references; bh=6ApWfuJ0D0g3QrelwnDPlSG8OOKZaWuA97rVS5nYc4w=; b=edrzuHGpl269YEeY3Qdr7h3PuQiX3sQd2OwCn61rGS2VB1CwaV1q+DUWKJhMLjwftf xPLbmkvOfbwvMx9XFPacF8lKCeATNj2GfagozSMEKtiSDnoKUmFPkpjfCjZnB1MnQsVv IiZBFfXVW+MBjCjzan2EtWWQ9ycCORPBZX0I9WLSNtjAvvWKMgKeJWwG+aSki/b3MmlP +Ed1eR/O3nPjgLdGD3DL8dCCaK6dpED1I+qDhCEWjuTu7MYZpgn+oTEoeOF8JIkTJDV8 2vcZgE5iapJzEw8F7sCV6Uv1nIcaIpX1imGzNudHmPc1wTzZQx18RONe4WyDhS8A8JI8 9EWg== X-Gm-Message-State: APjAAAX9LO+SgrzNzHgdHL0UgH0OKb3P6JWC3qOS5qxO2d9KVmGE5zfn PIonejWeMfhDNaKtM8LoMe8VEDJh X-Google-Smtp-Source: APXvYqwQvqQAxXTiDWY4asxbKBSqelPMmlT5UsNNQijJD9uQ1DtcN6V9TMS9RBEjgaRoB0Z57s1Yaw== X-Received: by 2002:a17:902:9a42:: with SMTP id x2mr12085789plv.194.1580011173480; Sat, 25 Jan 2020 19:59:33 -0800 (PST) Received: from localhost.localdomain ([184.63.162.180]) by smtp.gmail.com with ESMTPSA id 64sm11078650pfd.48.2020.01.25.19.59.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sat, 25 Jan 2020 19:59:33 -0800 (PST) From: John Fastabend To: bpf@vger.kernel.org Cc: bjorn.topel@intel.com, songliubraving@fb.com, john.fastabend@gmail.com, ast@kernel.org, daniel@iogearbox.net, toke@redhat.com, maciej.fijalkowski@intel.com, netdev@vger.kernel.org Subject: [PATCH bpf-next v2 2/3] bpf: xdp, virtio_net use access ptr macro for xdp enable check Date: Sat, 25 Jan 2020 19:58:52 -0800 Message-Id: <1580011133-17784-3-git-send-email-john.fastabend@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1580011133-17784-1-git-send-email-john.fastabend@gmail.com> References: <1580011133-17784-1-git-send-email-john.fastabend@gmail.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org virtio_net currently relies on rcu critical section to access the xdp program in its xdp_xmit handler. However, the pointer to the xdp program is only used to do a NULL pointer comparison to determine if xdp is enabled or not. Use rcu_access_pointer() instead of rcu_dereference() to reflect this. Then later when we drop rcu_read critical section virtio_net will not need in special handling. Signed-off-by: John Fastabend Acked-by: Jesper Dangaard Brouer --- drivers/net/virtio_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 4d7d5434..945eabc 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -501,7 +501,7 @@ static int virtnet_xdp_xmit(struct net_device *dev, /* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this * indicate XDP resources have been successfully allocated. */ - xdp_prog = rcu_dereference(rq->xdp_prog); + xdp_prog = rcu_access_pointer(rq->xdp_prog); if (!xdp_prog) return -ENXIO;