From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:48817 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751678AbaLBKCF (ORCPT ); Tue, 2 Dec 2014 05:02:05 -0500 Message-ID: <547D8E1A.5050307@iki.fi> Date: Tue, 02 Dec 2014 12:02:02 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Akihiro TSUKADA , Benjamin Larsson , linux-media@vger.kernel.org Subject: Re: Random memory corruption of fe[1]->dvb pointer References: <547BAC79.50702@southpole.se> <547CF9FC.5010101@southpole.se> <547D8AA0.4000403@gmail.com> In-Reply-To: <547D8AA0.4000403@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 12/02/2014 11:47 AM, Akihiro TSUKADA wrote: >> So at first it would be nice if someone could confirm my findings. >> Applying the same kind of code like my patch and unplug something that >> uses the affected frontend should be enough. > > I tried that for tc90522, and I could remove earth-pt3 > (which uses tc90522), tc90522 and tuner modules without any problem, > although earth-pt3 is a pci driver and does not use dvb-usb-v2. > >>>From your log(?) output, > I guess that rtl28xxu_exit() removed the attached demod module > (mn88472) and thus free'ed fe BEFORE calling dvb_usbv2_exit(), > from where dvb_unregister_frontend(fe) is called. > I think that the demod i2c device is removed automatically by > dvb_usbv2_i2c_exit() in dvb_usbv2_exit(), if you registered > the demod i2c device, and your adapter/bridge driver > should not try to remove it. Yes. You must unregister frontend before you remove driver. I have already added new callbacks detach tuner and frontend to avoid that, but there was yet again new issue as it removes rtl2832 demod driver first and mn88472 slave demod was put to i2c bus / adapter which is owned by rtl2832. So it will crash too. Solution is to convert rtl2832 to I2C binding (or convert mn88472 legacy DVB binding (which I don't allow :)). When rtl2832 driver is converted to I2C model it is not unloaded automatically and you could remove those in a correct order. But hey, mn88472 is still on staging :D regards Antti -- http://palosaari.fi/