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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 A0B99C433E0 for ; Fri, 8 Jan 2021 03:42:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7045F23601 for ; Fri, 8 Jan 2021 03:42:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727489AbhAHDmS (ORCPT ); Thu, 7 Jan 2021 22:42:18 -0500 Received: from mga12.intel.com ([192.55.52.136]:47617 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727236AbhAHDmS (ORCPT ); Thu, 7 Jan 2021 22:42:18 -0500 IronPort-SDR: 3e7xUh+hmmpzmmzNebRbx4lFweDcuBwrS2bCjcJJGqGrlDfm/2aTWQwN0dNZ/CZhAqIx3/TQcD ZwVK1qe59qqg== X-IronPort-AV: E=McAfee;i="6000,8403,9857"; a="156718750" X-IronPort-AV: E=Sophos;i="5.79,330,1602572400"; d="scan'208";a="156718750" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jan 2021 19:41:37 -0800 IronPort-SDR: 3Ps9BcQoldNuUzkLTt/ZDENe5nblFF2iLHxdw9VV0drtLwUtEKx4y+6Cw/0Y+5D0/VnWCsoJHO X+bk1teW0ZYw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.79,330,1602572400"; d="scan'208";a="463270096" Received: from unknown (HELO coxu-arch-shz.sh.intel.com) ([10.239.160.33]) by fmsmga001.fm.intel.com with ESMTP; 07 Jan 2021 19:41:35 -0800 From: Colin Xu To: virtualization@lists.linux-foundation.org Cc: kraxel@redhat.com, mst@redhat.com, jasowang@redhat.com, linux-kernel@vger.kernel.org, colin.xu@intel.com Subject: [PATCH] virtio_input: Prevent EV_MSC/MSC_TIMESTAMP loop storm for MT. Date: Fri, 8 Jan 2021 11:41:30 +0800 Message-Id: <20210108034130.499055-1-colin.xu@intel.com> X-Mailer: git-send-email 2.30.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In 'commit 29cc309d8bf1 ("HID: hid-multitouch: forward MSC_TIMESTAMP")', EV_MSC/MSC_TIMESTAMP is added to each before EV_SYN event. EV_MSC is configured as INPUT_PASS_TO_ALL. In case of a touch device which report MSC_TIMESTAMP: BE pass EV_MSC/MSC_TIMESTAMP to FE on receiving event from evdev. FE pass EV_MSC/MSC_TIMESTAMP back to BE. BE writes EV_MSC/MSC_TIMESTAMP to evdev due to INPUT_PASS_TO_ALL. BE receives extra EV_MSC/MSC_TIMESTAMP and pass to FE. >>> Each new frame becomes larger and larger. Disable EV_MSC/MSC_TIMESTAMP forwarding for MT. Signed-off-by: Colin Xu --- drivers/virtio/virtio_input.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c index f1f6208edcf5..244965c20d9b 100644 --- a/drivers/virtio/virtio_input.c +++ b/drivers/virtio/virtio_input.c @@ -64,6 +64,21 @@ static int virtinput_send_status(struct virtio_input *vi, unsigned long flags; int rc; + /* + * Since 29cc309d8bf1 (HID: hid-multitouch: forward MSC_TIMESTAMP), + * EV_MSC/MSC_TIMESTAMP is added to each before EV_SYN event. + * EV_MSC is configured as INPUT_PASS_TO_ALL. + * In case of touch device: + * BE pass EV_MSC/MSC_TIMESTAMP to FE on receiving event from evdev. + * FE pass EV_MSC/MSC_TIMESTAMP back to BE. + * BE writes EV_MSC/MSC_TIMESTAMP to evdev due to INPUT_PASS_TO_ALL. + * BE receives extra EV_MSC/MSC_TIMESTAMP and pass to FE. + * >>> Each new frame becomes larger and larger. + * Disable EV_MSC/MSC_TIMESTAMP forwarding for MT. + */ + if (vi->idev->mt && type == EV_MSC && code == MSC_TIMESTAMP) + return 0; + stsbuf = kzalloc(sizeof(*stsbuf), GFP_ATOMIC); if (!stsbuf) return -ENOMEM; -- 2.30.0