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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D26EC7EE2A for ; Mon, 5 Jun 2023 10:44:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231684AbjFEKo4 (ORCPT ); Mon, 5 Jun 2023 06:44:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232053AbjFEKor (ORCPT ); Mon, 5 Jun 2023 06:44:47 -0400 Received: from wp530.webpack.hosteurope.de (wp530.webpack.hosteurope.de [80.237.130.52]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56DCFDB; Mon, 5 Jun 2023 03:44:45 -0700 (PDT) Received: from [2a02:8108:8980:2478:8cde:aa2c:f324:937e]; authenticated by wp530.webpack.hosteurope.de running ExIM with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) id 1q67hb-0007rj-Rz; Mon, 05 Jun 2023 12:44:43 +0200 Message-ID: <88d8a7c3-0018-cc9a-13aa-e3262e20e4aa@leemhuis.info> Date: Mon, 5 Jun 2023 12:44:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: Sometimes DVB broken with commit 6769a0b7ee0c3b Content-Language: en-US, de-DE To: Mauro Carvalho Chehab Cc: Linux regressions mailing list , Hyunwoo Kim , Linux Media Mailing List , Thomas Voegtle , linux-kernel@vger.kernel.org References: <439d143b-1de7-6365-cf64-f1b44fd6d1cf@leemhuis.info> <20230605113727.69e7f309@sal.lan> From: Thorsten Leemhuis In-Reply-To: <20230605113727.69e7f309@sal.lan> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-bounce-key: webpack.hosteurope.de;regressions@leemhuis.info;1685961885;4d5ba9fc; X-HE-SMSGID: 1q67hb-0007rj-Rz Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05.06.23 12:37, Mauro Carvalho Chehab wrote: > Em Mon, 5 Jun 2023 11:38:49 +0200 > "Linux regression tracking (Thorsten Leemhuis)" escreveu: > >> Hi, Thorsten here, the Linux kernel's regression tracker. >> >> On 30.05.23 13:12, Thomas Voegtle wrote: >>> >>> I have the problem that sometimes my DVB card does not initialize >>> properly booting Linux 6.4-rc4. >>> This is not always, maybe in 3 out of 4 attempts. >>> When this happens somehow you don't see anything special in dmesg, but >>> the card just doesn't work. >>> >>> Reverting this helps: >>> commit 6769a0b7ee0c3b31e1b22c3fadff2bfb642de23f >>> Author: Hyunwoo Kim >>> Date:   Thu Nov 17 04:59:22 2022 +0000 >>> >>>     media: dvb-core: Fix use-after-free on race condition at dvb_frontend >>> >>> >>> I have: >>> 03:00.0 Multimedia video controller [0400]: Conexant Systems, Inc. >>> CX23887/8 >>> PCIe Broadcast Audio and Video Decoder with 3D Comb [14f1:8880] (rev 04) >>>         Subsystem: Hauppauge computer works Inc. Device [0070:c138] >>>         Kernel driver in use: cx23885 >> >> Hmmm, that was posted last Tuesday and received not a single reply. :-/ >> >> Hyunwoo Kim: could you please look at it, as it's a regression caused by >> a commit of yours (one that would be good to solve before 6.4 is >> finalized!)? And in case you are unable to do so let us know? >> >> But FWIW: >> >> Mauro: I wonder if this is something you or someone else has to look >> into, as Hyunwoo Kim posted a few times per months to Linux lists, but >> according to a quick search on lore hasn't posted anything since ~two >> months now. :-/ > > Yeah, I was slow applying this one, as I was afraid of it to cause > troubles. The DVB frontend state machine is complex, and uses a > semaphore to update its state. There was some past attempts of > addressing some lifetime issues there that we ended needing to revert > or not being applied, as the fix caused more harm than good. > [...] Thx for the update. That's unfortunate, but how it is sometimes. Which leads to a follow-up question: is reverting the culprit temporarily an option? Or did those old use-after-free problems became known to be a problem we can't live with anymore for another few months? Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr If I did something stupid, please tell me, as explained on that page.