From patchwork Thu Nov 5 20:21:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saeed Mahameed X-Patchwork-Id: 319759 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B4C6C4741F for ; Thu, 5 Nov 2020 20:22:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFE94221F8 for ; Thu, 5 Nov 2020 20:22:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="hv2URyXK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732528AbgKEUWX (ORCPT ); Thu, 5 Nov 2020 15:22:23 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:19775 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732328AbgKEUWV (ORCPT ); Thu, 5 Nov 2020 15:22:21 -0500 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Thu, 05 Nov 2020 12:22:24 -0800 Received: from sx1.mtl.com (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 5 Nov 2020 20:22:14 +0000 From: Saeed Mahameed To: Jakub Kicinski CC: , "David S. Miller" , "Maxim Mikityanskiy" , Tariq Toukan , "Saeed Mahameed" Subject: [net v2 7/7] net/mlx5e: Fix incorrect access of RCU-protected xdp_prog Date: Thu, 5 Nov 2020 12:21:29 -0800 Message-ID: <20201105202129.23644-8-saeedm@nvidia.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201105202129.23644-1-saeedm@nvidia.com> References: <20201105202129.23644-1-saeedm@nvidia.com> MIME-Version: 1.0 X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1604607744; bh=Me4k3oBtLi1R1bUzXFhth6SnIPa/YVgeeB1Nn0ImP/A=; h=From:To:CC:Subject:Date:Message-ID:X-Mailer:In-Reply-To: References:MIME-Version:Content-Transfer-Encoding:Content-Type: X-Originating-IP:X-ClientProxiedBy; b=hv2URyXKuTW9hQgokHO+yhEyfWFjxjlqsWVsg4rIpqVB7u/mkezgSUjQLbDl/sBga 4FdHGb9pWJYWAYTDKOExPPAE3DbrsGRFwyFvBeuaGlbo2UFiX3AxsnYj/bs6GL60TI Yuadzckc1ZZapUcwBDPVNtGxaFkXi+cB0EHVSMruy/5izAajd3vEHpQyFWT3y8up5b NXRcnka6TcR2affSHo1zh+HqUc/YJi4H+kYeuy+hxX2ke0eVHUZ0gMfR5EoQ6JquxS 4Md6olo24sjhA/I4RxayeVU0QBJ/cpPlVasJCC2pU0QNhPVCzwugvzS+oLv/CFMJWm ykvpw3Bc/eFOQ== Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Maxim Mikityanskiy rq->xdp_prog is RCU-protected and should be accessed only with rcu_access_pointer for the NULL check in mlx5e_poll_rx_cq. rq->xdp_prog may change on the fly only from one non-NULL value to another non-NULL value, so the checks in mlx5e_xdp_handle and mlx5e_poll_rx_cq will have the same result during one NAPI cycle, meaning that no additional synchronization is needed. Fixes: fe45386a2082 ("net/mlx5e: Use RCU to protect rq->xdp_prog") Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan Signed-off-by: Saeed Mahameed --- drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index 599f5b5ebc97..6628a0197b4e 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -1584,7 +1584,7 @@ int mlx5e_poll_rx_cq(struct mlx5e_cq *cq, int budget) } while ((++work_done < budget) && (cqe = mlx5_cqwq_get_cqe(cqwq))); out: - if (rq->xdp_prog) + if (rcu_access_pointer(rq->xdp_prog)) mlx5e_xdp_rx_poll_complete(rq); mlx5_cqwq_update_db_record(cqwq);