On Feb 20 2016 16:41, Takashi Sakamoto wrote:
> In IEC 61883-1, at bus-reset, applications can continue isochronous
> streaming by updating connections. In ALSA fireworks driver, the
> operation is executed in 'update' handler for bus driver.
>
> The connection resources are also changed in process contexts of PCM/MIDI
> applications. Therefore, bus-reset handling has race condition
> against connection. Current ALSA fireworks driver has a bug for the
> condition.
>
> This commit fixes the bug, by expand critical section with mutex. As a
> result, connection updating operation in bus-reset handler and connection
> changing operation in process context are serialized.
Oops. I forgot to add 'ALSA:' prefix to the commit title. I'm sorry but
would you please add it when merging to for-next branch?
> Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
> ---
> sound/firewire/fireworks/fireworks.c | 3 +++
> sound/firewire/fireworks/fireworks_stream.c | 6 ++----
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/sound/firewire/fireworks/fireworks.c b/sound/firewire/fireworks/fireworks.c
> index d5b19bc..8f27b67 100644
> --- a/sound/firewire/fireworks/fireworks.c
> +++ b/sound/firewire/fireworks/fireworks.c
> @@ -301,7 +301,10 @@ static void efw_update(struct fw_unit *unit)
> struct snd_efw *efw = dev_get_drvdata(&unit->device);
>
> snd_efw_transaction_bus_reset(efw->unit);
> +
> + mutex_lock(&efw->mutex);
> snd_efw_stream_update_duplex(efw);
> + mutex_unlock(&efw->mutex);
> }
>
> static void efw_remove(struct fw_unit *unit)
> diff --git a/sound/firewire/fireworks/fireworks_stream.c b/sound/firewire/fireworks/fireworks_stream.c
> index 968a40a..425db8d 100644
> --- a/sound/firewire/fireworks/fireworks_stream.c
> +++ b/sound/firewire/fireworks/fireworks_stream.c
> @@ -313,12 +313,10 @@ void snd_efw_stream_stop_duplex(struct snd_efw *efw)
>
> void snd_efw_stream_update_duplex(struct snd_efw *efw)
> {
> - if ((cmp_connection_update(&efw->out_conn) < 0) ||
> - (cmp_connection_update(&efw->in_conn) < 0)) {
> - mutex_lock(&efw->mutex);
> + if (cmp_connection_update(&efw->out_conn) < 0 ||
> + cmp_connection_update(&efw->in_conn) < 0) {
> stop_stream(efw, &efw->rx_stream);
> stop_stream(efw, &efw->tx_stream);
> - mutex_unlock(&efw->mutex);
> } else {
> amdtp_stream_update(&efw->rx_stream);
> amdtp_stream_update(&efw->tx_stream);
Regards
Takashi Sakamoto
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
