[PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

On 03/13/18 22:23, Andy Shevchenko wrote:

On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
[off-list ref] wrote:

quoted

In the current implementation, `rmmod snd_bcm2835` does not release
resources properly. It causes an oops when trying to list sound devices.

This commit fixes it.

Nice catch!

See my comments below.

quoted

 static void snd_devm_unregister_child(struct device *dev, void *res)
 {
        struct device *childdev = *(struct device **)res;
+       struct bcm2835_chip *chip = dev_get_drvdata(childdev);
+       struct snd_card *card = chip->card;
+
+       snd_card_free(card);
+       dev_set_drvdata(childdev, NULL);

AFAIU this is done by device core.

Maybe you are right. But I don't know, which function in the device core does it.
It is safe to have this line. So, I suggest to keep it.

quoted

        device_unregister(childdev);
 }
+static void snd_devm_release(struct device *dev)
+{
+       struct bcm2835_chip *chip = dev_get_drvdata(dev);
+
+       kfree(chip);
+}

quoted

 /* chip-specific constructor

@@ -122,7 +136,7 @@ static int snd_bcm2835_create(struct snd_card *card,

        err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
        if (err) {
-               snd_bcm2835_free(chip);
+               kfree(chip);

Do you call device_register() inside snd_device_new()?
In this case you might need put_device() here instead of simple kfree().

No, from what I see, device_register() does not happen inside snd_device_new().

quoted

                return err;
        }