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 X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60007C432C0 for ; Sun, 17 Nov 2019 08:57:49 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DA1C620740 for ; Sun, 17 Nov 2019 08:57:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="fzUs5+r/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA1C620740 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 2D8E61691; Sun, 17 Nov 2019 09:56:57 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 2D8E61691 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1573981067; bh=FYLyKGgCC1XjSaRMrQ+IDGPtJhI07WJhX5/reBWTqPE=; h=From:To:Date:In-Reply-To:References:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=fzUs5+r/r0/bxD5Q2SoyPn/oQpJlFsEi3AIXKIJmx8EmHhWRALzcNVyMVbAxX4Zyi iFki39YBRmN6E3s1+gHrraFk62WjdSzzhdvXy/CWcI1/rJEvcfYxF4gGzxhO66DPkf 14YyhCM/iQtDn9AqW5O6CBjEOm2wYuR1hDBbeyF4= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id B419FF8014F; Sun, 17 Nov 2019 09:53:35 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id DB150F8013A; Sun, 17 Nov 2019 09:53:30 +0100 (CET) Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id A3E33F800F1 for ; Sun, 17 Nov 2019 09:53:21 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz A3E33F800F1 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1EC44B234 for ; Sun, 17 Nov 2019 08:53:19 +0000 (UTC) From: Takashi Iwai To: alsa-devel@alsa-project.org Date: Sun, 17 Nov 2019 09:53:06 +0100 Message-Id: <20191117085308.23915-7-tiwai@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20191117085308.23915-1-tiwai@suse.de> References: <20191117085308.23915-1-tiwai@suse.de> Subject: [alsa-devel] [PATCH 6/8] ALSA: pcm: Add the support for sync-stop operation X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" The standard programming model of a PCM sound driver is to process snd_pcm_period_elapsed() from an interrupt handler. When a running stream is stopped, PCM core calls the trigger-STOP PCM ops, sets the stream state to SETUP, and moves on to the next step. This is performed in an atomic manner -- this could be called from the interrupt context, after all. The problem is that, if the stream goes further and reaches to the CLOSE state immediately, the stream might be still being processed in snd_pcm_period_elapsed() in the interrupt context, and hits a NULL dereference. Such a crash happens because of the atomic operation, and we can't wait until the stream-stop finishes. For addressing such a problem, this commit adds a new PCM ops, sync_stop. This gets called at the appropriate places that need a sync with the stream-stop, i.e. at hw_params, prepare and hw_free. Some drivers already have a similar mechanism implemented locally, and we'll refactor the code later. Signed-off-by: Takashi Iwai --- include/sound/pcm.h | 2 ++ sound/core/pcm_native.c | 15 +++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 25563317782c..8a89fa6fdd5e 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -59,6 +59,7 @@ struct snd_pcm_ops { int (*hw_free)(struct snd_pcm_substream *substream); int (*prepare)(struct snd_pcm_substream *substream); int (*trigger)(struct snd_pcm_substream *substream, int cmd); + int (*sync_stop)(struct snd_pcm_substream *substream); snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *substream); int (*get_time_info)(struct snd_pcm_substream *substream, struct timespec *system_ts, struct timespec *audio_ts, @@ -395,6 +396,7 @@ struct snd_pcm_runtime { wait_queue_head_t sleep; /* poll sleep */ wait_queue_head_t tsleep; /* transfer sleep */ struct fasync_struct *fasync; + bool stop_operating; /* sync_stop will be called */ /* -- private section -- */ void *private_data; diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 704ea75199e4..163d621ff238 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -568,6 +568,15 @@ static inline void snd_pcm_timer_notify(struct snd_pcm_substream *substream, #endif } +static void snd_pcm_sync_stop(struct snd_pcm_substream *substream) +{ + if (substream->runtime->stop_operating) { + substream->runtime->stop_operating = false; + if (substream->ops->sync_stop) + substream->ops->sync_stop(substream); + } +} + /** * snd_pcm_hw_param_choose - choose a configuration defined by @params * @pcm: PCM instance @@ -660,6 +669,8 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream, if (atomic_read(&substream->mmap_count)) return -EBADFD; + snd_pcm_sync_stop(substream); + params->rmask = ~0U; err = snd_pcm_hw_refine(substream, params); if (err < 0) @@ -788,6 +799,7 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream) snd_pcm_stream_unlock_irq(substream); if (atomic_read(&substream->mmap_count)) return -EBADFD; + snd_pcm_sync_stop(substream); if (substream->ops->hw_free) result = substream->ops->hw_free(substream); if (substream->managed_buffer_alloc) @@ -1313,6 +1325,7 @@ static void snd_pcm_post_stop(struct snd_pcm_substream *substream, int state) runtime->status->state = state; snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTOP); } + runtime->stop_operating = true; wake_up(&runtime->sleep); wake_up(&runtime->tsleep); } @@ -1589,6 +1602,7 @@ static void snd_pcm_post_resume(struct snd_pcm_substream *substream, int state) snd_pcm_trigger_tstamp(substream); runtime->status->state = runtime->status->suspended_state; snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MRESUME); + snd_pcm_sync_stop(substream); } static const struct action_ops snd_pcm_action_resume = { @@ -1709,6 +1723,7 @@ static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream, static int snd_pcm_do_prepare(struct snd_pcm_substream *substream, int state) { int err; + snd_pcm_sync_stop(substream); err = substream->ops->prepare(substream); if (err < 0) return err; -- 2.16.4 _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org https://mailman.alsa-project.org/mailman/listinfo/alsa-devel