From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751658AbbE0F4Y (ORCPT ); Wed, 27 May 2015 01:56:24 -0400 Received: from mga09.intel.com ([134.134.136.24]:31974 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751197AbbE0F4V (ORCPT ); Wed, 27 May 2015 01:56:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,502,1427785200"; d="scan'208";a="498716881" Message-ID: <55655C82.2040705@linux.intel.com> Date: Wed, 27 May 2015 13:56:18 +0800 From: "Zhang, Yanmin" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, xinhuix.pan@intel.com, jin.can.zhuang@intel.com, gregkh@linuxfoundation.org, alan@linux.intel.com Subject: Re: [PATCH V3 0/3] cdc-acm: fix incorrect runtime wakeup in acm_tty_write References: <55654475.6060500@linux.intel.com> In-Reply-To: <55654475.6060500@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2015/5/27 12:13, Zhang, Yanmin wrote: > Resend as V1/V2 have email format issue. Sorry for bothering. Greg, We have to abandon this patchset. Zhuang Jin Can, a USB expert, reviewed the patches. He says acm_tty_write already considers it carefully. acm_tty_write puts the urb to a delayed queue when acm->susp_count is not 0. acm_suspend adds 1 to acm->susp_count and acm_resume decreases 1 from it . Sorry for the bothering. Also thank Jin Can for the comments. Yanmin > > I use Thunderbird. It has no a button to enable LKML email simply. :) > > V3: Change email config to resend. > Add a space in comment. > > --- > > There is a scenario about cdc-acm utilization.Application opens > n_gsm tty and cdc-acm tty. cdc-acm tty connects to xhci device. > The application configures cdc-adm tty to n_gsm tty as ldisc tty. > > n_gsm=>cdc-acm=>xhci driver > > acm_tty_write can be called from n_gsm driver by ldisc connection, > and from application when application opens cdc-acm tty directly. > acm_tty_write wakes up the device by calling usb_autopm_get_interface_async, > which calls pm_runtime_get. However, pm_runtime_get can't wake up > the device before returning as it's an async wake up. Then, acm_tty_write > might access the device when it is off. > > The patchset fixes it by: > 1) add a new function usb_autopm_get_interface_upgrade to deal with > above 2 requirements; > 2) wake up device in n_gsm driver if n_gsm drivers calls cdc-acm driver; > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >