On 7/13/2021 4:28 PM, Takashi Iwai wrote:
...
+
+/**
+ * snd_devm_card_new - managed snd_card object creation
+ * @parent: the parent device object
+ * @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
+ * @xid: card identification (ASCII string)
+ * @module: top level module for locking
+ * @extra_size: allocate this extra size after the main soundcard structure
+ * @card_ret: the pointer to store the created card instance
+ *
+ * This function works like snd_card_new() but manages the allocated resource
+ * via devres, i.e. you don't need to free explicitly.
+ *
+ * When a snd_card object is created with this function and registered via
+ * snd_card_register(), the very first devres action to call snd_card_free()
+ * is added automatically. In that way, the resource disconnection is assured
+ * at first, then released in the expected order.
+ */
+int snd_devm_card_new(struct device *parent, int idx, const char *xid,
+ struct module *module, int extra_size,
+ struct snd_card **card_ret)
+{
+ struct snd_card *card;
+ int err;
+
+ *card_ret = NULL;
+ if (extra_size < 0)
+ extra_size = 0;
Maybe just make extra_size unsigned or even better size_t?
...
/**
* snd_card_ref - Get the card object from the index
@@ -481,6 +547,7 @@ EXPORT_SYMBOL_GPL(snd_card_disconnect_sync);
static int snd_card_do_free(struct snd_card *card)
{
+ card->releasing = true;
#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
if (snd_mixer_oss_notify_callback)
snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
@@ -498,7 +565,8 @@ static int snd_card_do_free(struct snd_card *card)
#endif
if (card->release_completion)
complete(card->release_completion);
- kfree(card);
+ if (!card->managed)
+ kfree(card);
return 0;
}
@@ -539,6 +607,9 @@ int snd_card_free(struct snd_card *card)
DECLARE_COMPLETION_ONSTACK(released);
int ret;
+ if (card->releasing)
+ return 0;
+
"card->releasing" use feels bit racy to me... something like below would
break it?
thread1 thread2
snd_card_free()
if(card->releasing) == false
thread1 goes sleep
snd_card_do_free()
card->releasing = true
run until the end
thread1 resume
continues with trying to release
card->release_completion = &released;
ret = snd_card_free_when_closed(card);
if (ret)
@@ -745,6 +816,11 @@ int snd_card_add_dev_attr(struct snd_card *card,
}
EXPORT_SYMBOL_GPL(snd_card_add_dev_attr);
+static void trigger_card_free(void *data)
+{
+ snd_card_free(data);
+}
+
/**
* snd_card_register - register the soundcard
* @card: soundcard structure
@@ -768,6 +844,15 @@ int snd_card_register(struct snd_card *card)
if (err < 0)
return err;
card->registered = true;
+ } else {
+ if (card->managed)
+ devm_remove_action(card->dev, trigger_card_free, card);
Not sure I understand, we are in _register function, so why do we remove
action?
+ }
+
+ if (card->managed) {
+ err = devm_add_action(card->dev, trigger_card_free, card);
+ if (err < 0)
+ return err;
}
err = snd_device_register_all(card);
