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=-15.2 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_SANE_1 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 218F3C4361B for ; Mon, 7 Dec 2020 08:54:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD6502311B for ; Mon, 7 Dec 2020 08:54:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726358AbgLGIx6 (ORCPT ); Mon, 7 Dec 2020 03:53:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726168AbgLGIx6 (ORCPT ); Mon, 7 Dec 2020 03:53:58 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14B7FC0613D0 for ; Mon, 7 Dec 2020 00:53:18 -0800 (PST) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kmCGe-0005Eb-At; Mon, 07 Dec 2020 09:53:12 +0100 Received: from mtr by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1kmCGc-0007ZD-L1; Mon, 07 Dec 2020 09:53:10 +0100 Date: Mon, 7 Dec 2020 09:53:10 +0100 From: Michael Tretter To: Thomas Haemmerle Cc: laurent.pinchart@ideasonboard.com, gregkh@linuxfoundation.org, balbi@kernel.org, hverkuil@xs4all.nl, linux-usb@vger.kernel.org, linux-media@vger.kernel.org Subject: Re: [PATCH v4] usb: gadget: uvc: fix multiple opens Message-ID: <20201207085310.GD1553@pengutronix.de> Mail-Followup-To: Michael Tretter , Thomas Haemmerle , laurent.pinchart@ideasonboard.com, gregkh@linuxfoundation.org, balbi@kernel.org, hverkuil@xs4all.nl, linux-usb@vger.kernel.org, linux-media@vger.kernel.org References: <2920c6ea-d191-a6cb-ec90-dda22bb9df55@wolfvision.net> <20201201192730.5633-1-thomas.haemmerle@wolfvision.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201201192730.5633-1-thomas.haemmerle@wolfvision.net> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 09:36:18 up 4 days, 21:03, 56 users, load average: 0.25, 0.62, 0.81 User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: mtr@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-usb@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, 01 Dec 2020 20:27:30 +0100, Thomas Haemmerle wrote: > Currently, the UVC function is activated when open on the corresponding > v4l2 device is called. > On another open the activation of the function fails since the > deactivation counter in `usb_function_activate` equals 0. However the > error is not returned to userspace since the open of the v4l2 device is > successful. > > On a close the function is deactivated (since deactivation counter still > equals 0) and the video is disabled in `uvc_v4l2_release`, although the > UVC application potentially is streaming. > > Move activation of UVC function to subscription on UVC_EVENT_SETUP > because there we can guarantee for a userspace application utilizing > UVC. > Block subscription on UVC_EVENT_SETUP while another application already > is subscribed to it, indicated by `bool func_connected` in > `struct uvc_device`. > Extend the `struct uvc_file_handle` with member `bool is_uvc_app_handle` > to tag it as the handle used by the userspace UVC application. > > With this a process is able to check capabilities of the v4l2 device > without deactivating the function for the actual UVC application. > > Signed-off-by: Thomas Haemmerle While I agree that this driver overall could really use some love, this patch at least fixes the driver for user space applications that scan for v4l2 devices. Reviewed-By: Michael Tretter > --- > v4: > - remove unnecessary inner parentheses > - keep and use the local video variable in `uvc_v4l2_release()` > > v3: > - replace `unsigned int connections` with `bool func_connected` > - rename `bool connected` to `bool is_uvc_app_handle` > > v2: > - fix deadlock in `uvc_v4l2_unsubscribe_event()` (mutex is already > locked in v4l2-core) introduced in v1 > - lock mutex in `uvc_v4l2_release()` to suppress ioctls and protect > connected > > drivers/usb/gadget/function/uvc.h | 2 ++ > drivers/usb/gadget/function/uvc_v4l2.c | 49 ++++++++++++++++++++++---- > 2 files changed, 44 insertions(+), 7 deletions(-) > > diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h > index 23ee25383c1f..893aaa70f81a 100644 > --- a/drivers/usb/gadget/function/uvc.h > +++ b/drivers/usb/gadget/function/uvc.h > @@ -117,6 +117,7 @@ struct uvc_device { > enum uvc_state state; > struct usb_function func; > struct uvc_video video; > + bool func_connected; > > /* Descriptors */ > struct { > @@ -147,6 +148,7 @@ static inline struct uvc_device *to_uvc(struct usb_function *f) > struct uvc_file_handle { > struct v4l2_fh vfh; > struct uvc_video *device; > + bool is_uvc_app_handle; > }; > > #define to_uvc_file_handle(handle) \ > diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c > index 4ca89eab6159..197c26f7aec6 100644 > --- a/drivers/usb/gadget/function/uvc_v4l2.c > +++ b/drivers/usb/gadget/function/uvc_v4l2.c > @@ -227,17 +227,55 @@ static int > uvc_v4l2_subscribe_event(struct v4l2_fh *fh, > const struct v4l2_event_subscription *sub) > { > + struct uvc_device *uvc = video_get_drvdata(fh->vdev); > + struct uvc_file_handle *handle = to_uvc_file_handle(fh); > + int ret; > + > if (sub->type < UVC_EVENT_FIRST || sub->type > UVC_EVENT_LAST) > return -EINVAL; > > - return v4l2_event_subscribe(fh, sub, 2, NULL); > + if (sub->type == UVC_EVENT_SETUP && uvc->func_connected) > + return -EBUSY; > + > + ret = v4l2_event_subscribe(fh, sub, 2, NULL); > + if (ret < 0) > + return ret; > + > + if (sub->type == UVC_EVENT_SETUP) { > + uvc->func_connected = true; > + handle->is_uvc_app_handle = true; > + uvc_function_connect(uvc); > + } > + > + return 0; > +} > + > +static void uvc_v4l2_disable(struct uvc_device *uvc) > +{ > + uvc->func_connected = false; > + uvc_function_disconnect(uvc); > + uvcg_video_enable(&uvc->video, 0); > + uvcg_free_buffers(&uvc->video.queue); > } > > static int > uvc_v4l2_unsubscribe_event(struct v4l2_fh *fh, > const struct v4l2_event_subscription *sub) > { > - return v4l2_event_unsubscribe(fh, sub); > + struct uvc_device *uvc = video_get_drvdata(fh->vdev); > + struct uvc_file_handle *handle = to_uvc_file_handle(fh); > + int ret; > + > + ret = v4l2_event_unsubscribe(fh, sub); > + if (ret < 0) > + return ret; > + > + if (sub->type == UVC_EVENT_SETUP && handle->is_uvc_app_handle) { > + uvc_v4l2_disable(uvc); > + handle->is_uvc_app_handle = false; > + } > + > + return 0; > } > > static long > @@ -292,7 +330,6 @@ uvc_v4l2_open(struct file *file) > handle->device = &uvc->video; > file->private_data = &handle->vfh; > > - uvc_function_connect(uvc); > return 0; > } > > @@ -304,11 +341,9 @@ uvc_v4l2_release(struct file *file) > struct uvc_file_handle *handle = to_uvc_file_handle(file->private_data); > struct uvc_video *video = handle->device; > > - uvc_function_disconnect(uvc); > - > mutex_lock(&video->mutex); > - uvcg_video_enable(video, 0); > - uvcg_free_buffers(&video->queue); > + if (handle->is_uvc_app_handle) > + uvc_v4l2_disable(uvc); > mutex_unlock(&video->mutex); > > file->private_data = NULL; > -- > 2.25.1 > >