From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx2.suse.de ([195.135.220.15]:47004 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751182AbeEPJXs (ORCPT ); Wed, 16 May 2018 05:23:48 -0400 Message-ID: <1526462623.25281.5.camel@suse.com> Subject: Re: [PATCH] [Patch v2] usbtv: Fix refcounting mixup From: Oliver Neukum To: Hans Verkuil , ben.hutchings@codethink.co.uk, gregkh@linuxfoundation.org, mchehab@s-opensource.com, linux-media@vger.kernel.org Cc: stable@vger.kernel.org Date: Wed, 16 May 2018 11:23:43 +0200 In-Reply-To: <1ee4b00d-9a55-92cf-e708-1e0c60ca4bfd@xs4all.nl> References: <20180515130744.19342-1-oneukum@suse.com> <85dd974b-c251-47a5-600d-77b009e2dfcd@xs4all.nl> <1526399190.31771.2.camel@suse.com> <1ee4b00d-9a55-92cf-e708-1e0c60ca4bfd@xs4all.nl> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Am Dienstag, den 15.05.2018, 18:01 +0200 schrieb Hans Verkuil: > On 05/15/2018 05:46 PM, Oliver Neukum wrote: > > Am Dienstag, den 15.05.2018, 16:28 +0200 schrieb Hans Verkuil: > > > On 05/15/18 15:07, Oliver Neukum wrote: > > > > usbtv_audio_fail: > > > > /* we must not free at this point */ > > > > - usb_get_dev(usbtv->udev); > > > > + v4l2_device_get(&usbtv->v4l2_dev); > > > > > > This is very confusing. I think it is much better to move the > > > > Yes. It confused me. > > > > > v4l2_device_register() call from usbtv_video_init to this probe function. > > > > Yes, but it is called here. So you want to do it after registering the > > audio? > > No, before. It's a global data structure, so this can be done before the > call to usbtv_video_init() as part of the top-level initialization of the > driver. Eh, but we cannot create a V4L device before the first device is connected and we must certainly create multiple V4L devices if multiple physical devices are connected. Maybe I am dense. Please elaborate. It seem to me that the driver is confusing because it uses multiple refcounts. Regards Oliver