From e8ad415b7a55cb9a9fbfc04696518d5ea0b609b3 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 15 Jul 2021 09:58:24 +0200 Subject: ALSA: core: Add managed card creation As a second step for preliminary to widen the devres usages among sound drivers, this patch adds a new ALSA core API function, snd_devm_card_new(), to create a snd_card object via devres. When a card object is created by this new function, snd_card_free() is called automatically and the card object resource gets released at the device unbinding time. However, the story isn't that simple. A caveat is that we have to call snd_card_free() at the very first of the whole resource release procedure, in order to assure that the all exposed devices on user-space are deleted and sync with processes accessing those devices before releasing resources. For achieving it, snd_card_register() adds a new devres action to trigger snd_card_free() automatically when the given card object is a "managed" one. Since usually snd_card_register() is the last step of the initialization, this should work in most cases. With all these tricks, some drivers can get rid of the whole driver remove callback code. About a bit of implementation details: the patch adds two new flags to snd_card object: managed and releasing. The former indicates that the object was created via snd_devm_card_new(), and the latter is used for avoiding the double-free of snd_card_free() calls. Both flags are fairly internal and likely uninteresting to normal users. Link: https://lore.kernel.org/r/20210715075941.23332-3-tiwai@suse.de Signed-off-by: Takashi Iwai --- include/sound/core.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/sound/core.h') diff --git a/include/sound/core.h b/include/sound/core.h index c4ade121727d..7885f903cd5a 100644 --- a/include/sound/core.h +++ b/include/sound/core.h @@ -117,6 +117,8 @@ struct snd_card { struct device card_dev; /* cardX object for sysfs */ const struct attribute_group *dev_groups[4]; /* assigned sysfs attr */ bool registered; /* card_dev is registered? */ + bool managed; /* managed via devres */ + bool releasing; /* during card free process */ int sync_irq; /* assigned irq, used for PCM sync */ wait_queue_head_t remove_sleep; @@ -274,6 +276,9 @@ extern int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int cmd); int snd_card_new(struct device *parent, int idx, const char *xid, struct module *module, int extra_size, struct snd_card **card_ret); +int snd_devm_card_new(struct device *parent, int idx, const char *xid, + struct module *module, size_t extra_size, + struct snd_card **card_ret); int snd_card_disconnect(struct snd_card *card); void snd_card_disconnect_sync(struct snd_card *card); -- cgit v1.2.3