From mboxrd@z Thu Jan 1 00:00:00 1970 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 95FE7C677F1 for ; Mon, 16 Jan 2023 16:30:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233207AbjAPQaz (ORCPT ); Mon, 16 Jan 2023 11:30:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233179AbjAPQaR (ORCPT ); Mon, 16 Jan 2023 11:30:17 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 446E239B95 for ; Mon, 16 Jan 2023 08:18:32 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D562F61047 for ; Mon, 16 Jan 2023 16:18:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7334C433EF; Mon, 16 Jan 2023 16:18:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673885911; bh=Q/rRuMYWOK/w/tLWxb9Ie3tw9DniL0DJikkmVHz0wYk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Mlv+5MRZBXvuW6beXqTYDycmWbpu+h1NlVG2A/A1grtLMpJoXXk/iCmrb5G0D3jSc 6zL1JT/Q9Ou9VaVvVtpErA3MK3NUKhe7zPwqhx3P6848NDLrqc0eORbjzlBwBLclV1 aVtnTfQlYD30SB/Ljn6sVopxbZ7BtLx7ERT2SlLU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Pilmore , Dave Jiang , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 231/658] ntb_netdev: Use dev_kfree_skb_any() in interrupt context Date: Mon, 16 Jan 2023 16:45:19 +0100 Message-Id: <20230116154920.099911951@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154909.645460653@linuxfoundation.org> References: <20230116154909.645460653@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Pilmore [ Upstream commit 5f7d78b2b12a9d561f48fa00bab29b40f4616dad ] TX/RX callback handlers (ntb_netdev_tx_handler(), ntb_netdev_rx_handler()) can be called in interrupt context via the DMA framework when the respective DMA operations have completed. As such, any calls by these routines to free skb's, should use the interrupt context safe dev_kfree_skb_any() function. Previously, these callback handlers would call the interrupt unsafe version of dev_kfree_skb(). This has not presented an issue on Intel IOAT DMA engines as that driver utilizes tasklets rather than a hard interrupt handler, like the AMD PTDMA DMA driver. On AMD systems, a kernel WARNING message is encountered, which is being issued from skb_release_head_state() due to in_hardirq() being true. Besides the user visible WARNING from the kernel, the other symptom of this bug was that TCP/IP performance across the ntb_netdev interface was very poor, i.e. approximately an order of magnitude below what was expected. With the repair to use dev_kfree_skb_any(), kernel WARNINGs from skb_release_head_state() ceased and TCP/IP performance, as measured by iperf, was on par with expected results, approximately 20 Gb/s on AMD Milan based server. Note that this performance is comparable with Intel based servers. Fixes: 765ccc7bc3d91 ("ntb_netdev: correct skb leak") Fixes: 548c237c0a997 ("net: Add support for NTB virtual ethernet device") Signed-off-by: Eric Pilmore Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/20221209000659.8318-1-epilmore@gigaio.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ntb_netdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ntb_netdev.c b/drivers/net/ntb_netdev.c index 1b7d588ff3c5..b701ee83e64a 100644 --- a/drivers/net/ntb_netdev.c +++ b/drivers/net/ntb_netdev.c @@ -137,7 +137,7 @@ static void ntb_netdev_rx_handler(struct ntb_transport_qp *qp, void *qp_data, enqueue_again: rc = ntb_transport_rx_enqueue(qp, skb, skb->data, ndev->mtu + ETH_HLEN); if (rc) { - dev_kfree_skb(skb); + dev_kfree_skb_any(skb); ndev->stats.rx_errors++; ndev->stats.rx_fifo_errors++; } @@ -192,7 +192,7 @@ static void ntb_netdev_tx_handler(struct ntb_transport_qp *qp, void *qp_data, ndev->stats.tx_aborted_errors++; } - dev_kfree_skb(skb); + dev_kfree_skb_any(skb); if (ntb_transport_tx_free_entry(dev->qp) >= tx_start) { /* Make sure anybody stopping the queue after this sees the new -- 2.35.1