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,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 47B84C433FF for ; Wed, 14 Aug 2019 17:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1DE6E20665 for ; Wed, 14 Aug 2019 17:21:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565803310; bh=ZOosVN0Ic6Q88AcFPeEupioIcmxpjRiFLM8kbGNB5nU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=n9pUgwB3GX72Xla2D7F26+s8iKSsNLWPsHB4ZzQhjUSTXTK975luiOFPXdleggKIY Ro/z7/P4u9b+JHKLTkDpIN76/tiEYnFL8d9rf8uEeV6Kl+ANjoh3J6jt13FzdBCxKs jRehQmM7da58RC2o+KXX7Mv5k6hB54YOtllnF8to= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729256AbfHNRVt (ORCPT ); Wed, 14 Aug 2019 13:21:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:59844 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730314AbfHNRJ1 (ORCPT ); Wed, 14 Aug 2019 13:09:27 -0400 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 869CA2133F; Wed, 14 Aug 2019 17:09:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565802567; bh=ZOosVN0Ic6Q88AcFPeEupioIcmxpjRiFLM8kbGNB5nU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c5fWbNoCc7gP+hGtJCYc0+HIEoZ6aCWYK4NqznkGPOwThydJUa9sxDI3j5SbFpT79 G80MPgWAs3sBULuMAl59Yzz1ZrJrthSme+5zizqV8xxDmRWfV2YoKn/MYYjXILXcd0 ugk2vxGqr2w1qkNCVPy76L6fINuV1lDmxRti+IBA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikita Yushchenko , Marc Kleine-Budde Subject: [PATCH 4.19 31/91] can: rcar_canfd: fix possible IRQ storm on high load Date: Wed, 14 Aug 2019 19:00:54 +0200 Message-Id: <20190814165751.018391194@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190814165748.991235624@linuxfoundation.org> References: <20190814165748.991235624@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nikita Yushchenko commit d4b890aec4bea7334ca2ca56fd3b12fb48a00cd1 upstream. We have observed rcar_canfd driver entering IRQ storm under high load, with following scenario: - rcar_canfd_global_interrupt() in entered due to Rx available, - napi_schedule_prep() is called, and sets NAPIF_STATE_SCHED in state - Rx fifo interrupts are masked, - rcar_canfd_global_interrupt() is entered again, this time due to error interrupt (e.g. due to overflow), - since scheduled napi poller has not yet executed, condition for calling napi_schedule_prep() from rcar_canfd_global_interrupt() remains true, thus napi_schedule_prep() gets called and sets NAPIF_STATE_MISSED flag in state, - later, napi poller function rcar_canfd_rx_poll() gets executed, and calls napi_complete_done(), - due to NAPIF_STATE_MISSED flag in state, this call does not clear NAPIF_STATE_SCHED flag from state, - on return from napi_complete_done(), rcar_canfd_rx_poll() unmasks Rx interrutps, - Rx interrupt happens, rcar_canfd_global_interrupt() gets called and calls napi_schedule_prep(), - since NAPIF_STATE_SCHED is set in state at this time, this call returns false, - due to that false return, rcar_canfd_global_interrupt() returns without masking Rx interrupt - and this results into IRQ storm: unmasked Rx interrupt happens again and again is misprocessed in the same way. This patch fixes that scenario by unmasking Rx interrupts only when napi_complete_done() returns true, which means it has cleared NAPIF_STATE_SCHED in state. Fixes: dd3bd23eb438 ("can: rcar_canfd: Add Renesas R-Car CAN FD driver") Signed-off-by: Nikita Yushchenko Cc: linux-stable Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/rcar/rcar_canfd.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/drivers/net/can/rcar/rcar_canfd.c +++ b/drivers/net/can/rcar/rcar_canfd.c @@ -1512,10 +1512,11 @@ static int rcar_canfd_rx_poll(struct nap /* All packets processed */ if (num_pkts < quota) { - napi_complete_done(napi, num_pkts); - /* Enable Rx FIFO interrupts */ - rcar_canfd_set_bit(priv->base, RCANFD_RFCC(ridx), - RCANFD_RFCC_RFIE); + if (napi_complete_done(napi, num_pkts)) { + /* Enable Rx FIFO interrupts */ + rcar_canfd_set_bit(priv->base, RCANFD_RFCC(ridx), + RCANFD_RFCC_RFIE); + } } return num_pkts; }