[ALSA] Add O_APPEND flag support to PCM

Added O_APPEND flag support to PCM to enable shared substreams
among multiple processes.  This mechanism is used by dmix and
dsnoop plugins.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/sound/usb/usx2y/usx2yhwdeppcm.c b/sound/usb/usx2y/usx2yhwdeppcm.c
index fe67a92e2a1a..88b72b52590f 100644
--- a/sound/usb/usx2y/usx2yhwdeppcm.c
+++ b/sound/usb/usx2y/usx2yhwdeppcm.c
@@ -632,7 +632,7 @@ static int usX2Y_pcms_lock_check(struct snd_card *card)
                 for (s = 0; s < 2; ++s) {
                         struct snd_pcm_substream *substream;
                         substream = pcm->streams[s].substream;
-                        if (substream && substream->ffile != NULL)
+                        if (SUBSTREAM_BUSY(substream))
                                 err = -EBUSY;
                 }
         }