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 BF8A1C433EF for ; Wed, 23 Mar 2022 08:08:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242444AbiCWIKI (ORCPT ); Wed, 23 Mar 2022 04:10:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242445AbiCWIKA (ORCPT ); Wed, 23 Mar 2022 04:10:00 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D935B74871 for ; Wed, 23 Mar 2022 01:08:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1648022908; x=1679558908; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=bKWUYaPmRwZBXbIQvYluCzRLQ9byY907LwzxS8aSO4k=; b=REAvQ9NyE17g5RFupR8A2MrjkFuSGo5Sx7rET5qbltc54pTtxGOTfCxC cCkcWtAqXAa/xFHk4vmqiN8glMpKkuyxfuV+wXNGqKISo6/sCnyQ8jyo6 v5lyQvut8/vK6PgkJP43l66rG/6hOA4mLSLQWdTQ1D8tc0a8uuPGXf4vT ZZgKU1kGpSavzsyQGz/D8tRvce0wgjWJERRbepaIpy/sdRtvy0Wp29SvM JtVOcRuu/kWONrkunoCAuxpRSGyS+Df+vTfIFwQ7yY3dIR11FEt45l+4/ 5LBt4OTp8v9MrtIdZJuIAhFJBR6LjnOUcdRMCoSgJa9DnTPY+B768KfXc Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10294"; a="245523663" X-IronPort-AV: E=Sophos;i="5.90,203,1643702400"; d="scan'208";a="245523663" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2022 01:08:28 -0700 X-IronPort-AV: E=Sophos;i="5.90,203,1643702400"; d="scan'208";a="560790474" Received: from arturlex-mobl1.ger.corp.intel.com (HELO [10.99.249.37]) ([10.99.249.37]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2022 01:08:27 -0700 Message-ID: Date: Wed, 23 Mar 2022 09:08:25 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH 3/4] ALSA: pcm: Fix races among concurrent prepare and hw_params/hw_free calls Content-Language: en-US To: Takashi Iwai , alsa-devel@alsa-project.org Cc: Hu Jiahui , linux-kernel@vger.kernel.org References: <20220322170720.3529-1-tiwai@suse.de> <20220322170720.3529-4-tiwai@suse.de> From: =?UTF-8?Q?Amadeusz_S=c5=82awi=c5=84ski?= In-Reply-To: <20220322170720.3529-4-tiwai@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/22/2022 6:07 PM, Takashi Iwai wrote: > Like the previous fixes to hw_params and hw_free ioctl races, we need > to paper over the concurrent prepare ioctl calls against hw_params and > hw_free, too. > > This patch implements the locking with the existing > runtime->buffer_mutex for prepare ioctls. Unlike the previous case > for snd_pcm_hw_hw_params() and snd_pcm_hw_free(), snd_pcm_prepare() is > performed to the linked streams, hence the lock can't be applied > simply on the top. For tracking the lock in each linked substream, we > modify snd_pcm_action_group() slightly and apply the buffer_mutex for > the case stream_lock=false (formerly there was no lock applied) > there. > > Cc: > Signed-off-by: Takashi Iwai > --- > sound/core/pcm_native.c | 32 ++++++++++++++++++-------------- > 1 file changed, 18 insertions(+), 14 deletions(-) > > diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c > index 266895374b83..0e4fbf5fd87b 100644 > --- a/sound/core/pcm_native.c > +++ b/sound/core/pcm_native.c > @@ -1190,15 +1190,17 @@ struct action_ops { > static int snd_pcm_action_group(const struct action_ops *ops, > struct snd_pcm_substream *substream, > snd_pcm_state_t state, > - bool do_lock) > + bool stream_lock) > { > struct snd_pcm_substream *s = NULL; > struct snd_pcm_substream *s1; > int res = 0, depth = 1; > > snd_pcm_group_for_each_entry(s, substream) { > - if (do_lock && s != substream) { > - if (s->pcm->nonatomic) > + if (s != substream) { > + if (!stream_lock) > + mutex_lock_nested(&s->runtime->buffer_mutex, depth); > + else if (s->pcm->nonatomic) > mutex_lock_nested(&s->self_group.mutex, depth); > else > spin_lock_nested(&s->self_group.lock, depth); Maybe if (!stream_lock) mutex_lock_nested(&s->runtime->buffer_mutex, depth); else snd_pcm_group_lock(&s->self_group, s->pcm->nonatomic); ? > @@ -1226,18 +1228,18 @@ static int snd_pcm_action_group(const struct action_ops *ops, > ops->post_action(s, state); > } > _unlock: > - if (do_lock) { > - /* unlock streams */ > - snd_pcm_group_for_each_entry(s1, substream) { > - if (s1 != substream) { > - if (s1->pcm->nonatomic) > - mutex_unlock(&s1->self_group.mutex); > - else > - spin_unlock(&s1->self_group.lock); > - } > - if (s1 == s) /* end */ > - break; > + /* unlock streams */ > + snd_pcm_group_for_each_entry(s1, substream) { > + if (s1 != substream) { > + if (!stream_lock) > + mutex_unlock(&s1->runtime->buffer_mutex); > + else if (s1->pcm->nonatomic) > + mutex_unlock(&s1->self_group.mutex); > + else > + spin_unlock(&s1->self_group.lock); And similarly to above, use snd_pcm_group_unlock() here? > } > + if (s1 == s) /* end */ > + break; > } > return res; > } > @@ -1367,10 +1369,12 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops, > > /* Guarantee the group members won't change during non-atomic action */ > down_read(&snd_pcm_link_rwsem); > + mutex_lock(&substream->runtime->buffer_mutex); > if (snd_pcm_stream_linked(substream)) > res = snd_pcm_action_group(ops, substream, state, false); > else > res = snd_pcm_action_single(ops, substream, state); > + mutex_unlock(&substream->runtime->buffer_mutex); > up_read(&snd_pcm_link_rwsem); > return res; > }