From patchwork Tue Jan 17 09:25:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Magnus Karlsson X-Patchwork-Id: 13104408 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB504C678D4 for ; Tue, 17 Jan 2023 09:28:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236419AbjAQJ2F (ORCPT ); Tue, 17 Jan 2023 04:28:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236601AbjAQJ1g (ORCPT ); Tue, 17 Jan 2023 04:27:36 -0500 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 558591E1ED; Tue, 17 Jan 2023 01:26:02 -0800 (PST) Received: by mail-wm1-x331.google.com with SMTP id o17-20020a05600c511100b003db021ef437so2549514wms.4; Tue, 17 Jan 2023 01:26:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Lf+DfBr7EiMoGbNIDvvLlIXu7J9dT9iJQIWXw6brQfg=; b=bPFSAcWHTn+xs92Sh1lDRG6xAyGayL0MRYw5UGd3RHdEYEUk6obwfMQS3RClnrNJl4 4fPcGGnbEB3ja/5aFsxgltIARJxHiDS8H7uUPCmCFb1BU+fT9mxP64ySh94tnRi62hh1 hrYRwaQ5fRMgvRG0GFlhV4Dhj8zZCEuYhsMywAbdql8pBY2FeiV+BbMsLjnz2v28ZJ8t Xz4NIy1qjBeBwXrwPVPQWRuQ80yRC9Zo+gCv77X1bOnJXeEP369HzzLztlzlfmmP/VVq axrRKf4H2YbTPgOdaVZx8pQHNYcADg/iaKQ5hv1YbVlcBj/hWBr880eqYGvXIvLd/87n SPHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Lf+DfBr7EiMoGbNIDvvLlIXu7J9dT9iJQIWXw6brQfg=; b=vFgI1IO2cAQKYA/AFaTxjftXpW4IR0lsIXHgmWmvh0TaQLBM09+/Oghmd1DaFcZUcC bSBzwfGZ9W9XK/L9iUksWOu5ct3yFLIzSUo0ZIvlWONJUran8oRcDHAeIQlimLHK5eQo p+pOnyn75E/qC6vRcyvfhLMEhHV1MMwLQXgTQlOfqMGg1qw+m4UWSuf8szAiBlBSj3ac k91cQY/krqlHAJ7WMB3VtAJOR7Ltr/ktgcfPqcM0VdhSdbykj5NP8yladQ9DHZyfEUeD NlqFYeIv15er1/EAfqqbiwurgsq1bHd2F7ei1Z6bYkTREnTvS4SRbNpj/M7j36Dm4EUG VbiA== X-Gm-Message-State: AFqh2kp+ZULxUcbBXPH8NPvGxq/nHZH1ZhMJVsA06Y4XEdMEWiD17jJW X4Qhk2MvPzDPdS3g3FEka/w= X-Google-Smtp-Source: AMrXdXsbGElYmFMwcKgfKSb/g0qJNV9oeYIXA1MZkaJB57yzw2vwFUS0+0EMZAZLWd9y+SElwx5NGw== X-Received: by 2002:a1c:cc17:0:b0:3d9:fb8a:b2c5 with SMTP id h23-20020a1ccc17000000b003d9fb8ab2c5mr2364821wmb.16.1673947560649; Tue, 17 Jan 2023 01:26:00 -0800 (PST) Received: from localhost.localdomain (h-176-10-254-193.A165.priv.bahnhof.se. [176.10.254.193]) by smtp.gmail.com with ESMTPSA id u21-20020a7bc055000000b003d9aa76dc6asm48008881wmc.0.2023.01.17.01.25.58 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Jan 2023 01:25:59 -0800 (PST) From: Magnus Karlsson To: magnus.karlsson@intel.com, bjorn@kernel.org, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, jonathan.lemon@gmail.com, maciej.fijalkowski@intel.com, kuba@kernel.org, toke@redhat.com, pabeni@redhat.com, davem@davemloft.net, aelior@marvell.com, manishc@marvell.com, horatiu.vultur@microchip.com, UNGLinuxDriver@microchip.com, mst@redhat.com, jasowang@redhat.com, ioana.ciornei@nxp.com, madalin.bucur@nxp.com Cc: bpf@vger.kernel.org Subject: [PATCH net 2/5] lan966x: execute xdp_do_flush() before napi_complete_done() Date: Tue, 17 Jan 2023 10:25:30 +0100 Message-Id: <20230117092533.5804-3-magnus.karlsson@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230117092533.5804-1-magnus.karlsson@gmail.com> References: <20230117092533.5804-1-magnus.karlsson@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Magnus Karlsson Make sure that xdp_do_flush() is always executed before napi_complete_done(). This is important for two reasons. First, a redirect to an XSKMAP assumes that a call to xdp_do_redirect() from napi context X on CPU Y will be follwed by a xdp_do_flush() from the same napi context and CPU. This is not guaranteed if the napi_complete_done() is executed before xdp_do_flush(), as it tells the napi logic that it is fine to schedule napi context X on another CPU. Details from a production system triggering this bug using the veth driver can be found following the first link below. The second reason is that the XDP_REDIRECT logic in itself relies on being inside a single NAPI instance through to the xdp_do_flush() call for RCU protection of all in-kernel data structures. Details can be found in the second link below. Fixes: a825b611c7c1 ("net: lan966x: Add support for XDP_REDIRECT") Signed-off-by: Magnus Karlsson Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/ Acked-by: Steen Hegelund --- drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c index 5314c064ceae..55b484b10562 100644 --- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c @@ -608,12 +608,12 @@ static int lan966x_fdma_napi_poll(struct napi_struct *napi, int weight) lan966x_fdma_rx_reload(rx); } - if (counter < weight && napi_complete_done(napi, counter)) - lan_wr(0xff, lan966x, FDMA_INTR_DB_ENA); - if (redirect) xdp_do_flush(); + if (counter < weight && napi_complete_done(napi, counter)) + lan_wr(0xff, lan966x, FDMA_INTR_DB_ENA); + return counter; }