[alsa-devel] [PATCH] ALSA: fireworks/bebob: fix refering to released resources at unplugging

[Takashi Iwai]

At Wed, 21 Jan 2015 08:07:30 +0900,
Takashi Sakamoto wrote:
> 
> Unplugging devices can cause disorder by releasing streaming resources
> before stopping playbacking/capturing substreams. This commit forces
> the state of ALSA character devices into disconnect before releasing
> the resources.

This isn't enough, unfortunately.  snd_card_disconnect() itself
doesn't sync, merely disconnects and stops the streams, etc, thus the
file handles may be still opened.

In general, releasing the resources should be done in either in card's
private_free or snd_device's free callback where all files have been
already released.  For example, bebob_remove() should just call
snd_card_free_when_closed() (that invokes snd_card_disconnect()
internally) and call the reset (kfree() and *_destroy()) in a card's
free callback.


Takashi

> 
> Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
> ---
>  sound/firewire/bebob/bebob.c         | 3 ++-
>  sound/firewire/fireworks/fireworks.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/firewire/bebob/bebob.c b/sound/firewire/bebob/bebob.c
> index fc19c99..41eb1ce 100644
> --- a/sound/firewire/bebob/bebob.c
> +++ b/sound/firewire/bebob/bebob.c
> @@ -306,10 +306,11 @@ static void bebob_remove(struct fw_unit *unit)
>  	if (bebob == NULL)
>  		return;
>  
> +	snd_card_disconnect(bebob->card);
> +
>  	kfree(bebob->maudio_special_quirk);
>  
>  	snd_bebob_stream_destroy_duplex(bebob);
> -	snd_card_disconnect(bebob->card);
>  	snd_card_free_when_closed(bebob->card);
>  }
>  
> diff --git a/sound/firewire/fireworks/fireworks.c b/sound/firewire/fireworks/fireworks.c
> index 3e2ed8e..21fb50f 100644
> --- a/sound/firewire/fireworks/fireworks.c
> +++ b/sound/firewire/fireworks/fireworks.c
> @@ -289,10 +289,11 @@ static void efw_remove(struct fw_unit *unit)
>  {
>  	struct snd_efw *efw = dev_get_drvdata(&unit->device);
>  
> +	snd_card_disconnect(efw->card);
> +
>  	snd_efw_stream_destroy_duplex(efw);
>  	snd_efw_transaction_remove_instance(efw);
>  
> -	snd_card_disconnect(efw->card);
>  	snd_card_free_when_closed(efw->card);
>  }
>  
> -- 
> 2.1.0
>