ALSA: fireworks/bebob/dice/oxfw: allow stream destructor after releasing runtime

Currently stream destructor in each driver has a problem to be called in
a context in which sound card object is released, because the destructors
call amdtp_stream_pcm_abort() and touch PCM runtime data.

The PCM runtime data is destroyed in application's context with
snd_pcm_close(), on the other hand PCM substream data is destroyed after
sound card object is released, in most case after all of ALSA character
devices are released. When PCM runtime is destroyed and PCM substream is
remained, amdtp_stream_pcm_abort() touches PCM runtime data and causes
Null-pointer-dereference.

This commit changes stream destructors and allows each driver to call
it after releasing runtime.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/sound/firewire/oxfw/oxfw-stream.c b/sound/firewire/oxfw/oxfw-stream.c
index bda845a..29ccb36 100644
--- a/sound/firewire/oxfw/oxfw-stream.c
+++ b/sound/firewire/oxfw/oxfw-stream.c
@@ -337,6 +337,10 @@ void snd_oxfw_stream_stop_simplex(struct snd_oxfw *oxfw,
 	stop_stream(oxfw, stream);
 }
 
+/*
+ * This function should be called before starting the stream or after stopping
+ * the streams.
+ */
 void snd_oxfw_stream_destroy_simplex(struct snd_oxfw *oxfw,
 				     struct amdtp_stream *stream)
 {
@@ -347,8 +351,6 @@ void snd_oxfw_stream_destroy_simplex(struct snd_oxfw *oxfw,
 	else
 		conn = &oxfw->in_conn;
 
-	stop_stream(oxfw, stream);
-
 	amdtp_stream_destroy(stream);
 	cmp_connection_destroy(conn);
 }