From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:58357 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752349AbdDCIht (ORCPT ); Mon, 3 Apr 2017 04:37:49 -0400 Date: Mon, 03 Apr 2017 10:37:42 +0200 Message-ID: From: Takashi Iwai To: Kuninori Morimoto Cc: Mark Brown , Linux-Renesas , Linux-ALSA , Lars-Peter , Simon Subject: Re: [alsa-devel] [RFC][PATCH] ASoC: soc-core: verify Sound Card normality In-Reply-To: <87fuhpnbnu.wl%kuninori.morimoto.gx@renesas.com> References: <87vaqsajo0.wl%kuninori.morimoto.gx@renesas.com> <20170330215334.zwashvjerpfnkk3u@sirena.org.uk> <878tninh21.wl%kuninori.morimoto.gx@renesas.com> <87fuhpnbnu.wl%kuninori.morimoto.gx@renesas.com> MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: On Mon, 03 Apr 2017 10:26:05 +0200, Kuninori Morimoto wrote: > > > Hi Takashi-san > > > > So, we can call snd_soc_unregister_card() whenever CPU/Codec/Platform > > > were unregsiterd. > > > > In theory yes, but you should be careful to do so, e.g. make sure that > > it won't be called again by the removal/unbind of other components / > > drivers. > > > > I suggested snd_card_disconnect() because it doesn't release resources > > by itself, but it just disconnects from the further accesses. So, > > double-free won't happen in this case. It makes the hotunplug safer > > as long as the drivers manage the resource releases properly. > > I had checked many unbind/bind pattern/order on 2nd [RFC] patch which I posted. > At first, I believe Oops on unbind/bind issue was solved on it. > 2nd, if my understanding was correct, it doesn't have double-free issue, > or something like that. > But, I'm not 100% sure about 2nd, thus it has [RFC] on patch. Ah, I see that snd_soc_unregister_card() has the check of card->instantiated, so it should be fine to call multiple times. thanks, Takashi