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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 24845C33CB2 for ; Tue, 14 Jan 2020 10:12:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE57720678 for ; Tue, 14 Jan 2020 10:12:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578996738; bh=k18qRjP/nywpIHZ3grDId+QnddItalWgK5eGRgAKNkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EP3Ek4kgFHOSzq5XqLw0e8dt1IQJaM9YERdwqSbefyhJWDIPnlZzb77ZuRs8yH9V9 FiKz9GwS9hWfL+5iJFE4BGK3TYiJRLfO8zY8tFF6zkdhDcjarJNH5y4/0kNusp+2e2 eAbjMiUoi2iCX+rQJ8L2ob8qzDeqFyuZmPQFqJzk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732925AbgANKMR (ORCPT ); Tue, 14 Jan 2020 05:12:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:48304 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732908AbgANKMN (ORCPT ); Tue, 14 Jan 2020 05:12:13 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 47B19207FF; Tue, 14 Jan 2020 10:12:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578996732; bh=k18qRjP/nywpIHZ3grDId+QnddItalWgK5eGRgAKNkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v2dRy8DIc4r3NOWH6D2FFXi9oHOovTIcY+bDmbxkyxf66tMM6Y0QtDfG4KmX1cZQM nFNoVgfhf3d/jtDnmJfHd4g/yBuOWG1EVhTCoRYorIZ2Ni9RsZDQFCJ7NgIUz+/NnY RpWV/13yzYvKGBGQ4M7y/3l2PhPdHXKncWF5ity0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Florian Faber , Marc Kleine-Budde Subject: [PATCH 4.9 14/31] can: mscan: mscan_rx_poll(): fix rx path lockup when returning from polling to irq mode Date: Tue, 14 Jan 2020 11:02:06 +0100 Message-Id: <20200114094342.408517831@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200114094334.725604663@linuxfoundation.org> References: <20200114094334.725604663@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Florian Faber commit 2d77bd61a2927be8f4e00d9478fe6996c47e8d45 upstream. Under load, the RX side of the mscan driver can get stuck while TX still works. Restarting the interface locks up the system. This behaviour could be reproduced reliably on a MPC5121e based system. The patch fixes the return value of the NAPI polling function (should be the number of processed packets, not constant 1) and the condition under which IRQs are enabled again after polling is finished. With this patch, no more lockups were observed over a test period of ten days. Fixes: afa17a500a36 ("net/can: add driver for mscan family & mpc52xx_mscan") Signed-off-by: Florian Faber Cc: linux-stable Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/mscan/mscan.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) --- a/drivers/net/can/mscan/mscan.c +++ b/drivers/net/can/mscan/mscan.c @@ -392,13 +392,12 @@ static int mscan_rx_poll(struct napi_str struct net_device *dev = napi->dev; struct mscan_regs __iomem *regs = priv->reg_base; struct net_device_stats *stats = &dev->stats; - int npackets = 0; - int ret = 1; + int work_done = 0; struct sk_buff *skb; struct can_frame *frame; u8 canrflg; - while (npackets < quota) { + while (work_done < quota) { canrflg = in_8(®s->canrflg); if (!(canrflg & (MSCAN_RXF | MSCAN_ERR_IF))) break; @@ -419,18 +418,18 @@ static int mscan_rx_poll(struct napi_str stats->rx_packets++; stats->rx_bytes += frame->can_dlc; - npackets++; + work_done++; netif_receive_skb(skb); } - if (!(in_8(®s->canrflg) & (MSCAN_RXF | MSCAN_ERR_IF))) { - napi_complete(&priv->napi); - clear_bit(F_RX_PROGRESS, &priv->flags); - if (priv->can.state < CAN_STATE_BUS_OFF) - out_8(®s->canrier, priv->shadow_canrier); - ret = 0; + if (work_done < quota) { + if (likely(napi_complete_done(&priv->napi, work_done))) { + clear_bit(F_RX_PROGRESS, &priv->flags); + if (priv->can.state < CAN_STATE_BUS_OFF) + out_8(®s->canrier, priv->shadow_canrier); + } } - return ret; + return work_done; } static irqreturn_t mscan_isr(int irq, void *dev_id)