From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967200AbcHBODt (ORCPT ); Tue, 2 Aug 2016 10:03:49 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:56864 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966142AbcHBODl (ORCPT ); Tue, 2 Aug 2016 10:03:41 -0400 Subject: Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error To: Oliver Neukum References: <1469729992-6228-1-git-send-email-robert.foss@collabora.com> <1470140595.30985.20.camel@suse.com> Cc: pprabhu@chromium.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org From: Robert Foss Message-ID: <04ca38d7-6538-d220-3fe7-7ece503ce4ad@collabora.com> Date: Tue, 2 Aug 2016 09:54:04 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1470140595.30985.20.camel@suse.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016-08-02 08:23 AM, Oliver Neukum wrote: > On Thu, 2016-07-28 at 14:19 -0400, robert.foss@collabora.com wrote: >> From: Prathmesh Prabhu >> >> Implemented queued response handling. This queue is processed every >> time the >> WDM_READ flag is cleared. >> >> In case of a read error, userspace may not actually read the data, >> since the >> driver returns an error through wdm_poll. After this, the underlying >> device may >> attempt to send us more data, but the queue is not processed. While >> userspace is >> also blocked, because the read error is never cleared. > > Could you explain why user space cannot just read more data? > That will clear the error. Userspace certainly could read more data, but for the case when userspace doesn't read and clear a potential an error, we still would like to not be stuck if the device sends more data. I hope that answers your question, if not I'll try to be more elaborate. > > Regards > Oliver > >