[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, 3 insertions, 2 deletions

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 998bacefc8f8..cebf0310a8dc 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -368,7 +368,8 @@ struct snd_pcm_substream {
         struct snd_pcm_group *group;            /* pointer to current group */
         /* -- assigned files -- */
         void *file;
-        struct file *ffile;
+        int ref_count;
+        unsigned int f_flags;
         void (*pcm_release)(struct snd_pcm_substream *);
 #if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE)
         /* -- OSS things -- */
@@ -387,7 +388,7 @@ struct snd_pcm_substream {
         unsigned int hw_opened: 1;
 };
 
-#define SUBSTREAM_BUSY(substream) ((substream)->file != NULL)
+#define SUBSTREAM_BUSY(substream) ((substream)->ref_count > 0)
 
 
 struct snd_pcm_str {