From patchwork Tue May 18 16:51:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Takashi Iwai X-Patchwork-Id: 442520 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 5F818C433ED for ; Tue, 18 May 2021 16:56:01 +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 D614A6109E for ; Tue, 18 May 2021 16:56:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D614A6109E 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 71B41178A; Tue, 18 May 2021 18:55:09 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 71B41178A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1621356959; bh=6wHq/rtM5QG6NJeTsu9wYhhd7h/B4OcaWWpiColL0D0=; h=From:To:Subject:Date:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=AXDA5peT9MP6I+Rdm5nQj964Wpe+CsqSv3t3euiKieSX1THXAxHfi73MYvKqaEqzM D1OHYjyd4skJxToownZgMxFFSGzn2Yg5VKGcUjQEtlIS9hDgyj4qAREpejqk3lHEaB 0jtUBQgPjTz0d03GS2dbtQ+uhFEDIkw1/PTlGcAU= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 2B26AF804D8; Tue, 18 May 2021 18:52:20 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 656A4F804AB; Tue, 18 May 2021 18:52:15 +0200 (CEST) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 26D69F80272 for ; Tue, 18 May 2021 18:52:05 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 26D69F80272 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6C729B1C2; Tue, 18 May 2021 16:52:03 +0000 (UTC) From: Takashi Iwai To: alsa-devel@alsa-project.org Subject: [PATCH 5/7] ALSA: control: Track in-flight control read/write/tlv accesses Date: Tue, 18 May 2021 18:51:59 +0200 Message-Id: <20210518165201.24376-6-tiwai@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210518165201.24376-1-tiwai@suse.de> References: <20210518165201.24376-1-tiwai@suse.de> MIME-Version: 1.0 Cc: Andrey Grodzovsky 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: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" Although we introduced the power state check at the entrance of the common handler for control API (and other interfaces), there can be still some pending tasks that already went into the ioctl handler, and those may access the hardware even after the power state check; currently the problem is seen typically for the kcontrol access paths. If a system wants to assure the free from hw access (like the PCI rescan feature we're going to implement in future), this situation must be avoided, and we have to sync such in-flight tasks finishing. For that purpose, this patch introduces a few new things: - A refcount, power_ref, and a wait queue, power_ref_sleep, to the card object - A few new helpers, snd_power_ref(), snd_power_unref(), snd_power_ref_and_wait(), and snd_power_sync_ref() In the code paths that call kctl info/read/write/tlv ops, we check the power state again but at this time with the newly introduced snd_power_ref_and_wait() instead. This function also takes the card.power_ref refcount for tracking this in-flight task. Once after the access finishes, snd_power_unref() is called to released the refcount. So the driver can sync via snd_power_sync_ref() assuring that all in-flight tasks have been finished. As of this patch, snd_power_sync_ref() is called only at snd_card_disconnect(), but it'll be used in other places in future. Note that atomic_t is used for power_ref intentionally instead of refcount_t. It's because of the design of refcount_t type; it cannot be zero-based, and it cannot do dec_and_test() call for multiple times. Also, this patch changes snd_power_wait() to accept only SNDRV_CTL_POWER_D0, which is the only value that makes sense. In later patch, the snd_power_wait() calls will be simplified. Signed-off-by: Takashi Iwai --- include/sound/core.h | 31 ++++++++++++++++++ sound/core/control.c | 23 +++++++++++--- sound/core/control_compat.c | 5 ++- sound/core/init.c | 63 ++++++++++++++++++++++++++++++++----- 4 files changed, 108 insertions(+), 14 deletions(-) diff --git a/include/sound/core.h b/include/sound/core.h index d69dfc6c4953..430d775b3c0e 100644 --- a/include/sound/core.h +++ b/include/sound/core.h @@ -128,7 +128,9 @@ struct snd_card { #ifdef CONFIG_PM unsigned int power_state; /* power state */ + atomic_t power_ref; wait_queue_head_t power_sleep; + wait_queue_head_t power_ref_sleep; #endif #if IS_ENABLED(CONFIG_SND_MIXER_OSS) @@ -151,12 +153,41 @@ static inline void snd_power_change_state(struct snd_card *card, unsigned int st wake_up(&card->power_sleep); } +/** + * snd_power_ref - Take the reference count for power control + * @card: sound card object + * + * The power_ref reference of the card is used for managing to block + * the snd_power_sync_ref() operation. This function increments the reference. + * The counterpart snd_power_unref() has to be called appropriately later. + */ +static inline void snd_power_ref(struct snd_card *card) +{ + atomic_inc(&card->power_ref); +} + +/** + * snd_power_unref - Release the reference count for power control + * @card: sound card object + */ +static inline void snd_power_unref(struct snd_card *card) +{ + if (atomic_dec_and_test(&card->power_ref)) + wake_up(&card->power_ref_sleep); +} + /* init.c */ int snd_power_wait(struct snd_card *card, unsigned int power_state); +int snd_power_ref_and_wait(struct snd_card *card); +void snd_power_sync_ref(struct snd_card *card); #else /* ! CONFIG_PM */ static inline int snd_power_wait(struct snd_card *card, unsigned int state) { return 0; } +static inline void snd_power_ref(struct snd_card *card) {} +static inline void snd_power_unref(struct snd_card *card) {} +static inline int snd_power_ref_and_wait(struct snd_card *card) { return 0; } +static inline void snd_power_sync_ref(struct snd_card *card) {} #define snd_power_get_state(card) ({ (void)(card); SNDRV_CTL_POWER_D0; }) #define snd_power_change_state(card, state) do { (void)(card); } while (0) diff --git a/sound/core/control.c b/sound/core/control.c index 5e8b77855e5d..37f6f2ca0543 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -995,7 +995,10 @@ static int __snd_ctl_elem_info(struct snd_card *card, #ifdef CONFIG_SND_DEBUG info->access = 0; #endif - result = kctl->info(kctl, info); + result = snd_power_ref_and_wait(card); + if (!result) + result = kctl->info(kctl, info); + snd_power_unref(card); if (result >= 0) { snd_BUG_ON(info->access); index_offset = snd_ctl_get_ioff(kctl, &info->id); @@ -1085,7 +1088,10 @@ static int snd_ctl_elem_read(struct snd_card *card, if (!snd_ctl_skip_validation(&info)) fill_remaining_elem_value(control, &info, pattern); - ret = kctl->get(kctl, control); + ret = snd_power_ref_and_wait(card); + if (!ret) + ret = kctl->get(kctl, control); + snd_power_unref(card); if (ret < 0) return ret; if (!snd_ctl_skip_validation(&info) && @@ -1147,7 +1153,10 @@ static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file, } snd_ctl_build_ioff(&control->id, kctl, index_offset); - result = kctl->put(kctl, control); + result = snd_power_ref_and_wait(card); + if (!result) + result = kctl->put(kctl, control); + snd_power_unref(card); if (result < 0) { up_write(&card->controls_rwsem); return result; @@ -1658,7 +1667,7 @@ static int call_tlv_handler(struct snd_ctl_file *file, int op_flag, {SNDRV_CTL_TLV_OP_CMD, SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND}, }; struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)]; - int i; + int i, ret; /* Check support of the request for this element. */ for (i = 0; i < ARRAY_SIZE(pairs); ++i) { @@ -1676,7 +1685,11 @@ static int call_tlv_handler(struct snd_ctl_file *file, int op_flag, vd->owner != NULL && vd->owner != file) return -EPERM; - return kctl->tlv.c(kctl, op_flag, size, buf); + ret = snd_power_ref_and_wait(file->card); + if (!ret) + ret = kctl->tlv.c(kctl, op_flag, size, buf); + snd_power_unref(file->card); + return ret; } static int read_tlv_buf(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id, diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c index 57b73ab57506..b9fe1ead435b 100644 --- a/sound/core/control_compat.c +++ b/sound/core/control_compat.c @@ -184,7 +184,10 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id, return -ENOMEM; } info->id = *id; - err = kctl->info(kctl, info); + err = snd_power_ref_and_wait(card); + if (!err) + err = kctl->info(kctl, info); + snd_power_unref(card); up_read(&card->controls_rwsem); if (err >= 0) { err = info->type; diff --git a/sound/core/init.c b/sound/core/init.c index ef41f5b3a240..d11636fac608 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -220,6 +220,8 @@ int snd_card_new(struct device *parent, int idx, const char *xid, mutex_init(&card->memory_mutex); #ifdef CONFIG_PM init_waitqueue_head(&card->power_sleep); + init_waitqueue_head(&card->power_ref_sleep); + atomic_set(&card->power_ref, 0); #endif init_waitqueue_head(&card->remove_sleep); card->sync_irq = -1; @@ -442,6 +444,7 @@ int snd_card_disconnect(struct snd_card *card) #ifdef CONFIG_PM wake_up(&card->power_sleep); + snd_power_sync_ref(card); #endif return 0; } @@ -1002,21 +1005,28 @@ EXPORT_SYMBOL(snd_card_file_remove); #ifdef CONFIG_PM /** - * snd_power_wait - wait until the power-state is changed. - * @card: soundcard structure - * @power_state: expected power state + * snd_power_ref_and_wait - wait until the card gets powered up + * @card: soundcard structure + * + * Take the power_ref reference count of the given card, and + * wait until the card gets powered up to SNDRV_CTL_POWER_D0 state. + * The refcount is down again while sleeping until power-up, hence this + * function can be used for syncing the floating control ops accesses, + * typically around calling control ops. * - * Waits until the power-state is changed. + * The caller needs to pull down the refcount via snd_power_unref() later + * no matter whether the error is returned from this function or not. * - * Return: Zero if successful, or a negative error code. + * Return: Zero if successful, or a negative error code. */ -int snd_power_wait(struct snd_card *card, unsigned int power_state) +int snd_power_ref_and_wait(struct snd_card *card) { wait_queue_entry_t wait; int result = 0; + snd_power_ref(card); /* fastpath */ - if (snd_power_get_state(card) == power_state) + if (snd_power_get_state(card) == SNDRV_CTL_POWER_D0) return 0; init_waitqueue_entry(&wait, current); add_wait_queue(&card->power_sleep, &wait); @@ -1025,13 +1035,50 @@ int snd_power_wait(struct snd_card *card, unsigned int power_state) result = -ENODEV; break; } - if (snd_power_get_state(card) == power_state) + if (snd_power_get_state(card) == SNDRV_CTL_POWER_D0) break; + snd_power_unref(card); set_current_state(TASK_UNINTERRUPTIBLE); schedule_timeout(30 * HZ); + snd_power_ref(card); } remove_wait_queue(&card->power_sleep, &wait); return result; } +EXPORT_SYMBOL_GPL(snd_power_ref_and_wait); + +/** + * snd_power_wait - wait until the card gets powered up (old form) + * @card: soundcard structure + * @power_state: expected power state + * + * Wait until the card gets powered up to SNDRV_CTL_POWER_D0 state. + * @power_state must be SNDRV_CTL_POWER_D0. + * + * Return: Zero if successful, or a negative error code. + */ +int snd_power_wait(struct snd_card *card, unsigned int power_state) +{ + int ret; + + if (WARN_ON(power_state != SNDRV_CTL_POWER_D0)) + return 0; + ret = snd_power_ref_and_wait(card); + snd_power_unref(card); + return ret; +} EXPORT_SYMBOL(snd_power_wait); + +/** + * snd_power_sync_ref - wait until the card power_ref is freed + * @card: sound card object + * + * This function is used to synchronize with the pending power_ref being + * released. + */ +void snd_power_sync_ref(struct snd_card *card) +{ + wait_event(card->power_ref_sleep, !atomic_read(&card->power_ref)); +} +EXPORT_SYMBOL_GPL(snd_power_sync_ref); #endif /* CONFIG_PM */