[alsa-devel] [PATCH 2/4] ALSA: pcm: Don't add internal PCMs to PCM device list

20 Feb 2015

An internal PCM object shouldn't be added to the PCM device list, as
it's never accessed directly from the user-space, and it has no proc
or any similar accesses.  Currently, it's excluded in snd_pcm_get()
and snd_pcm_next(), but it's easier not to add such an object to the
list.
Actually, the whole snd_pcm_dev_register() can be skipped for an
internal PCM.  So this patch changes the code there, but also
addresses the uninitialized list_head access.
Signed-off-by: Takashi Iwai tiwai@suse.de
---
 sound/core/pcm.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 89206e9c3578..92bbb5143b83 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -49,8 +49,6 @@ static struct snd_pcm *snd_pcm_get(struct snd_card *card, int device)
    struct snd_pcm *pcm;
list_for_each_entry(pcm, &snd_pcm_devices, list) {
-		if (pcm->internal)
-			continue;
    	if (pcm->card == card && pcm->device == device)
    		return pcm;
    }
@@ -62,8 +60,6 @@ static int snd_pcm_next(struct snd_card *card, int device)
    struct snd_pcm *pcm;
list_for_each_entry(pcm, &snd_pcm_devices, list) {
-		if (pcm->internal)
-			continue;
    	if (pcm->card == card && pcm->device > device)
    		return pcm->device;
    	else if (pcm->card->number > card->number)
@@ -76,6 +72,9 @@ static int snd_pcm_add(struct snd_pcm *newpcm)
 {
    struct snd_pcm *pcm;
+	if (newpcm->internal)
+		return 0;
+
    list_for_each_entry(pcm, &snd_pcm_devices, list) {
    	if (pcm->card == newpcm->card && pcm->device == newpcm->device)
    		return -EBUSY;
@@ -782,6 +781,9 @@ static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
    pcm->card = card;
    pcm->device = device;
    pcm->internal = internal;
+	mutex_init(&pcm->open_mutex);
+	init_waitqueue_head(&pcm->open_wait);
+	INIT_LIST_HEAD(&pcm->list);
    if (id)
    	strlcpy(pcm->id, id, sizeof(pcm->id));
    if ((err = snd_pcm_new_stream(pcm, SNDRV_PCM_STREAM_PLAYBACK, playback_count)) < 0) {
@@ -792,8 +794,6 @@ static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
    	snd_pcm_free(pcm);
    	return err;
    }
-	mutex_init(&pcm->open_mutex);
-	init_waitqueue_head(&pcm->open_wait);
    if ((err = snd_device_new(card, SNDRV_DEV_PCM, pcm, &ops)) < 0) {
    	snd_pcm_free(pcm);
    	return err;
@@ -1075,15 +1075,16 @@ static int snd_pcm_dev_register(struct snd_device *device)
    if (snd_BUG_ON(!device || !device->device_data))
    	return -ENXIO;
    pcm = device->device_data;
+	if (pcm->internal)
+		return 0;
+
    mutex_lock(&register_mutex);
    err = snd_pcm_add(pcm);
-	if (err) {
-		mutex_unlock(&register_mutex);
-		return err;
-	}
+	if (err)
+		goto unlock;
    for (cidx = 0; cidx < 2; cidx++) {
    	int devtype = -1;
-		if (pcm->streams[cidx].substream == NULL || pcm->internal)
+		if (pcm->streams[cidx].substream == NULL)
    		continue;
    	switch (cidx) {
    	case SNDRV_PCM_STREAM_PLAYBACK:
@@ -1098,9 +1099,8 @@ static int snd_pcm_dev_register(struct snd_device *device)
    				  &snd_pcm_f_ops[cidx], pcm,
    				  &pcm->streams[cidx].dev);
    	if (err < 0) {
-			list_del(&pcm->list);
-			mutex_unlock(&register_mutex);
-			return err;
+			list_del_init(&pcm->list);
+			goto unlock;
    	}
for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
@@ -1110,8 +1110,9 @@ static int snd_pcm_dev_register(struct snd_device *device)
    list_for_each_entry(notify, &snd_pcm_notify_list, list)
    	notify->n_register(pcm);
+ unlock:
    mutex_unlock(&register_mutex);
-	return 0;
+	return err;
 }
static int snd_pcm_dev_disconnect(struct snd_device *device)
-- 
2.3.0


    