[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, 55 insertions, 26 deletions

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 7b5729c..36d6765 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1284,13 +1284,16 @@ static int snd_pcm_reset(struct snd_pcm_substream *substream)
 /*
  * prepare ioctl
  */
-static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream, int state)
+/* we use the second argument for updating f_flags */
+static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream,
+			       int f_flags)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
 		return -EBADFD;
 	if (snd_pcm_running(substream))
 		return -EBUSY;
+	substream->f_flags = f_flags;
 	return 0;
 }
 
@@ -1319,17 +1322,26 @@ static struct action_ops snd_pcm_action_prepare = {
 /**
  * snd_pcm_prepare
  * @substream: the PCM substream instance
+ * @file: file to refer f_flags
  *
  * Prepare the PCM substream to be triggerable.
  */
-static int snd_pcm_prepare(struct snd_pcm_substream *substream)
+static int snd_pcm_prepare(struct snd_pcm_substream *substream,
+			   struct file *file)
 {
 	int res;
 	struct snd_card *card = substream->pcm->card;
+	int f_flags;
+
+	if (file)
+		f_flags = file->f_flags;
+	else
+		f_flags = substream->f_flags;
 
 	snd_power_lock(card);
 	if ((res = snd_power_wait(card, SNDRV_CTL_POWER_D0)) >= 0)
-		res = snd_pcm_action_nonatomic(&snd_pcm_action_prepare, substream, 0);
+		res = snd_pcm_action_nonatomic(&snd_pcm_action_prepare,
+					       substream, f_flags);
 	snd_power_unlock(card);
 	return res;
 }
@@ -1340,7 +1352,7 @@ static int snd_pcm_prepare(struct snd_pcm_substream *substream)
 
 static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream, int state)
 {
-	if (substream->ffile->f_flags & O_NONBLOCK)
+	if (substream->f_flags & O_NONBLOCK)
 		return -EAGAIN;
 	substream->runtime->trigger_master = substream;
 	return 0;
@@ -2015,6 +2027,10 @@ static void pcm_release_private(struct snd_pcm_substream *substream)
 
 void snd_pcm_release_substream(struct snd_pcm_substream *substream)
 {
+	substream->ref_count--;
+	if (substream->ref_count > 0)
+		return;
+
 	snd_pcm_drop(substream);
 	if (substream->hw_opened) {
 		if (substream->ops->hw_free != NULL)
@@ -2041,6 +2057,11 @@ int snd_pcm_open_substream(struct snd_pcm *pcm, int stream,
 	err = snd_pcm_attach_substream(pcm, stream, file, &substream);
 	if (err < 0)
 		return err;
+	if (substream->ref_count > 1) {
+		*rsubstream = substream;
+		return 0;
+	}
+
 	substream->no_mmap_ctrl = 0;
 	err = snd_pcm_hw_constraints_init(substream);
 	if (err < 0) {
@@ -2086,17 +2107,20 @@ static int snd_pcm_open_file(struct file *file,
 	if (err < 0)
 		return err;
 
-	pcm_file = kzalloc(sizeof(*pcm_file), GFP_KERNEL);
-	if (pcm_file == NULL) {
-		snd_pcm_release_substream(substream);
-		return -ENOMEM;
+	if (substream->ref_count > 1)
+		pcm_file = substream->file;
+	else {
+		pcm_file = kzalloc(sizeof(*pcm_file), GFP_KERNEL);
+		if (pcm_file == NULL) {
+			snd_pcm_release_substream(substream);
+			return -ENOMEM;
+		}
+		str = substream->pstr;
+		substream->file = pcm_file;
+		substream->pcm_release = pcm_release_private;
+		pcm_file->substream = substream;
+		snd_pcm_add_file(str, pcm_file);
 	}
-	str = substream->pstr;
-	substream->file = pcm_file;
-	substream->pcm_release = pcm_release_private;
-	pcm_file->substream = substream;
-	snd_pcm_add_file(str, pcm_file);
-
 	file->private_data = pcm_file;
 	*rpcm_file = pcm_file;
 	return 0;
@@ -2506,7 +2530,8 @@ static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
 	return 0;
 }
 		
-static int snd_pcm_common_ioctl1(struct snd_pcm_substream *substream,
+static int snd_pcm_common_ioctl1(struct file *file,
+				 struct snd_pcm_substream *substream,
 				 unsigned int cmd, void __user *arg)
 {
 	snd_assert(substream != NULL, return -ENXIO);
@@ -2531,7 +2556,7 @@ static int snd_pcm_common_ioctl1(struct snd_pcm_substream *substream,
 	case SNDRV_PCM_IOCTL_CHANNEL_INFO:
 		return snd_pcm_channel_info_user(substream, arg);
 	case SNDRV_PCM_IOCTL_PREPARE:
-		return snd_pcm_prepare(substream);
+		return snd_pcm_prepare(substream, file);
 	case SNDRV_PCM_IOCTL_RESET:
 		return snd_pcm_reset(substream);
 	case SNDRV_PCM_IOCTL_START:
@@ -2573,7 +2598,8 @@ static int snd_pcm_common_ioctl1(struct snd_pcm_substream *substream,
 	return -ENOTTY;
 }
 
-static int snd_pcm_playback_ioctl1(struct snd_pcm_substream *substream,
+static int snd_pcm_playback_ioctl1(struct file *file,
+				   struct snd_pcm_substream *substream,
 				   unsigned int cmd, void __user *arg)
 {
 	snd_assert(substream != NULL, return -ENXIO);
@@ -2649,10 +2675,11 @@ static int snd_pcm_playback_ioctl1(struct snd_pcm_substream *substream,
 		return result < 0 ? result : 0;
 	}
 	}
-	return snd_pcm_common_ioctl1(substream, cmd, arg);
+	return snd_pcm_common_ioctl1(file, substream, cmd, arg);
 }
 
-static int snd_pcm_capture_ioctl1(struct snd_pcm_substream *substream,
+static int snd_pcm_capture_ioctl1(struct file *file,
+				  struct snd_pcm_substream *substream,
 				  unsigned int cmd, void __user *arg)
 {
 	snd_assert(substream != NULL, return -ENXIO);
@@ -2728,7 +2755,7 @@ static int snd_pcm_capture_ioctl1(struct snd_pcm_substream *substream,
 		return result < 0 ? result : 0;
 	}
 	}
-	return snd_pcm_common_ioctl1(substream, cmd, arg);
+	return snd_pcm_common_ioctl1(file, substream, cmd, arg);
 }
 
 static long snd_pcm_playback_ioctl(struct file *file, unsigned int cmd,
@@ -2741,7 +2768,8 @@ static long snd_pcm_playback_ioctl(struct file *file, unsigned int cmd,
 	if (((cmd >> 8) & 0xff) != 'A')
 		return -ENOTTY;
 
-	return snd_pcm_playback_ioctl1(pcm_file->substream, cmd, (void __user *)arg);
+	return snd_pcm_playback_ioctl1(file, pcm_file->substream, cmd,
+				       (void __user *)arg);
 }
 
 static long snd_pcm_capture_ioctl(struct file *file, unsigned int cmd,
@@ -2754,7 +2782,8 @@ static long snd_pcm_capture_ioctl(struct file *file, unsigned int cmd,
 	if (((cmd >> 8) & 0xff) != 'A')
 		return -ENOTTY;
 
-	return snd_pcm_capture_ioctl1(pcm_file->substream, cmd, (void __user *)arg);
+	return snd_pcm_capture_ioctl1(file, pcm_file->substream, cmd,
+				      (void __user *)arg);
 }
 
 int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
@@ -2766,12 +2795,12 @@ int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
 	fs = snd_enter_user();
 	switch (substream->stream) {
 	case SNDRV_PCM_STREAM_PLAYBACK:
-		result = snd_pcm_playback_ioctl1(substream,
-						 cmd, (void __user *)arg);
+		result = snd_pcm_playback_ioctl1(NULL, substream, cmd,
+						 (void __user *)arg);
 		break;
 	case SNDRV_PCM_STREAM_CAPTURE:
-		result = snd_pcm_capture_ioctl1(substream,
-						cmd, (void __user *)arg);
+		result = snd_pcm_capture_ioctl1(NULL, substream, cmd,
+						(void __user *)arg);
 		break;
 	default:
 		result = -EINVAL;