From patchwork Mon Jan 27 00:14:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Fastabend X-Patchwork-Id: 1229478 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.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=bpf-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=b2/IUtdu; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 485VcM0wgSz9sRR for ; Mon, 27 Jan 2020 11:14:42 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727250AbgA0AOm (ORCPT ); Sun, 26 Jan 2020 19:14:42 -0500 Received: from mail-pj1-f66.google.com ([209.85.216.66]:50519 "EHLO mail-pj1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726444AbgA0AOl (ORCPT ); Sun, 26 Jan 2020 19:14:41 -0500 Received: by mail-pj1-f66.google.com with SMTP id r67so2271747pjb.0; Sun, 26 Jan 2020 16:14:41 -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=g9j0lMDO8NoNU4KTbS42+2WezLD8kVVyGGPJ2HPGp/M=; b=b2/IUtdu18/t4bYGGOQ7x5MWjXe0RvXpuaSe36Y2GK8n+4PhxfH23p2ePlTepBHC9q S8WwMTyHRkmfSV2OdzyW3aFwb+4DtzOHYElM/CD1yDEf0LsPZx5tGnVFtQ1dcYGvHcvY mkW33Ggd1dL5n5llbrjzKwY/XwY4vp614NKRj8GEAdYgdk6AdmzRjpw+bnm+x2kjGiJ2 egbuub+FkmL4vIA4kFXkT8zFuJGpOtTJV++TOTFCDBw3/YgOg41GcfikeSQcARLRKikC k1ySwv6tKO2uiFp37lJvVdTeT8WmHBjTX4R8p5uZw/0JFUsK+7pW5YIetVQ7eiY7hXTE vf4g== 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=g9j0lMDO8NoNU4KTbS42+2WezLD8kVVyGGPJ2HPGp/M=; b=BTJbTO04uLtwUN2QK8R2ecEBBXBTif3dW/yFbIHloo3fdGtFgxe1N1IZ8oCJBXHhi2 lKDkjciR2ca0ZKHRGCm9uYrYIQDW5PzwhJ8kvocb67tYHaub+vLufvQ4XI6bOHmhMYMk TTSCavNLYB7KLJdJ3r5Z7IRwfgsPfxFPFpb7EPQ8hu8gzNQG4yl0fKLDen1AxjcawZrh hhT2NfnFQhD0Klk8IG+ukexhEd26IwIey29++2DewDFTgrNZYgE7XZmMrq+NFiQMRE+9 lcIUXvXWQ+dCRvz0k1nYcZpcBccUA4dPkj/9vSVq3x4ZlCmouv03XdHt6ba65McRjDYg TRtQ== X-Gm-Message-State: APjAAAUKnZaGZOZn/VVSQWS6VULJfl46SJPn8C1k+zQaZ8+JrmOEdl4+ bpJEgjvD+zIbST+KegQdUBsjnpGA X-Google-Smtp-Source: APXvYqztDq2yJzJ1c3OzJhrSUTP0qhBn1h/Gxq5DXts3xNuqVcULO20YQ5lUODekPeFyzBao8+iGUA== X-Received: by 2002:a17:902:8f8a:: with SMTP id z10mr15532830plo.169.1580084080980; Sun, 26 Jan 2020 16:14:40 -0800 (PST) Received: from localhost.localdomain ([184.63.162.180]) by smtp.gmail.com with ESMTPSA id i23sm13326949pfo.11.2020.01.26.16.14.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 26 Jan 2020 16:14:40 -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 v3 2/3] bpf: xdp, virtio_net use access ptr macro for xdp enable check Date: Sun, 26 Jan 2020 16:14:01 -0800 Message-Id: <1580084042-11598-3-git-send-email-john.fastabend@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1580084042-11598-1-git-send-email-john.fastabend@gmail.com> References: <1580084042-11598-1-git-send-email-john.fastabend@gmail.com> Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@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. Acked-by: Jesper Dangaard Brouer Signed-off-by: John Fastabend Acked-by: Maciej Fijalkowski --- 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;