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 7A8C9C433F5 for ; Tue, 22 Mar 2022 17:08:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239393AbiCVRJ0 (ORCPT ); Tue, 22 Mar 2022 13:09:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239202AbiCVRJQ (ORCPT ); Tue, 22 Mar 2022 13:09:16 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F6AE71ED1 for ; Tue, 22 Mar 2022 10:07:48 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 3AB67210F0; Tue, 22 Mar 2022 17:07:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1647968867; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OKjFtB5KBr9W4w3NflnR7TkFxvAb0C5HMxfUzYIzr7s=; b=Vw95QBvC7cbTiU9SNUtLQSonYr3TkhQcan8iNTv8RiCH8N1dR+YThU56V5EDKHoqkvvrUO ZzvOcAW8EFpXpuZUKdhywBM/+IHGdAZM+/2uurakRCxllv4CKA5qHde1H122A1vQsT1pdO W0wKG48wPmQeihrQTEG9036FwahmFNk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1647968867; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OKjFtB5KBr9W4w3NflnR7TkFxvAb0C5HMxfUzYIzr7s=; b=OU5aFBrDmu/SozBe6LOmSsOl+7vDH57qPQHFE/j9z8rXUuMYXfJbFMfrYXrZUo6aRgnhzl wdUl6cLEyeF+L9DQ== Received: from alsa1.nue.suse.com (alsa1.suse.de [10.160.4.42]) by relay2.suse.de (Postfix) with ESMTP id 29758A3B89; Tue, 22 Mar 2022 17:07:47 +0000 (UTC) From: Takashi Iwai To: alsa-devel@alsa-project.org Cc: Hu Jiahui , linux-kernel@vger.kernel.org Subject: [PATCH 3/4] ALSA: pcm: Fix races among concurrent prepare and hw_params/hw_free calls Date: Tue, 22 Mar 2022 18:07:19 +0100 Message-Id: <20220322170720.3529-4-tiwai@suse.de> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220322170720.3529-1-tiwai@suse.de> References: <20220322170720.3529-1-tiwai@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); @@ -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); } + 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; } -- 2.31.1