ALSA: Fix limit of 8 PCM devices in SNDRV_CTL_IOCTL_PCM_NEXT_DEVICE

When compiled with CONFIG_SND_DYNAMIC_MINORS the ALSA core is fine
to have more than 8 PCM devices per card, except one place - the
SNDRV_CTL_IOCTL_PCM_NEXT_DEVICE ioctl, which will not enumerate
devices > 7. This patch fixes the issue, changing the devices list
organisation.

Instead of adding new device to the tail, the list is now kept always
ordered (by card number, then device number). Thus, during enumeration,
it is easy to discover the fact that there is no more given card's
devices.

Additionally the device field of struct snd_pcm had to be changed to int,
as its "unsignednity" caused a lot of problems when comparing it to
potentially negative signed values. (-1 is 0xffffffff or even more then ;-)

Signed-off-by: Pawel Moll <pawel.moll@st.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

1 files changed, 37 insertions, 13 deletions

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index ece25c718e95..517388b2eba9 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -42,7 +42,7 @@ static int snd_pcm_dev_free(struct snd_device *device);
 static int snd_pcm_dev_register(struct snd_device *device);
 static int snd_pcm_dev_disconnect(struct snd_device *device);
 
-static struct snd_pcm *snd_pcm_search(struct snd_card *card, int device)
+static struct snd_pcm *snd_pcm_get(struct snd_card *card, int device)
 {
 	struct snd_pcm *pcm;
 
@@ -53,6 +53,37 @@ static struct snd_pcm *snd_pcm_search(struct snd_card *card, int device)
 	return NULL;
 }
 
+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->card == card && pcm->device > device)
+			return pcm->device;
+		else if (pcm->card->number > card->number)
+			return -1;
+	}
+	return -1;
+}
+
+static int snd_pcm_add(struct snd_pcm *newpcm)
+{
+	struct snd_pcm *pcm;
+
+	list_for_each_entry(pcm, &snd_pcm_devices, list) {
+		if (pcm->card == newpcm->card && pcm->device == newpcm->device)
+			return -EBUSY;
+		if (pcm->card->number > newpcm->card->number ||
+				(pcm->card == newpcm->card &&
+				pcm->device > newpcm->device)) {
+			list_add(&newpcm->list, pcm->list.prev);
+			return 0;
+		}
+	}
+	list_add_tail(&newpcm->list, &snd_pcm_devices);
+	return 0;
+}
+
 static int snd_pcm_control_ioctl(struct snd_card *card,
 				 struct snd_ctl_file *control,
 				 unsigned int cmd, unsigned long arg)
@@ -65,14 +96,7 @@ static int snd_pcm_control_ioctl(struct snd_card *card,
 			if (get_user(device, (int __user *)arg))
 				return -EFAULT;
 			mutex_lock(&register_mutex);
-			device = device < 0 ? 0 : device + 1;
-			while (device < SNDRV_PCM_DEVICES) {
-				if (snd_pcm_search(card, device))
-					break;
-				device++;
-			}
-			if (device == SNDRV_PCM_DEVICES)
-				device = -1;
+			device = snd_pcm_next(card, device);
 			mutex_unlock(&register_mutex);
 			if (put_user(device, (int __user *)arg))
 				return -EFAULT;
@@ -98,7 +122,7 @@ static int snd_pcm_control_ioctl(struct snd_card *card,
 			if (get_user(subdevice, &info->subdevice))
 				return -EFAULT;
 			mutex_lock(&register_mutex);
-			pcm = snd_pcm_search(card, device);
+			pcm = snd_pcm_get(card, device);
 			if (pcm == NULL) {
 				err = -ENXIO;
 				goto _error;
@@ -931,11 +955,11 @@ static int snd_pcm_dev_register(struct snd_device *device)
 
 	snd_assert(pcm != NULL && device != NULL, return -ENXIO);
 	mutex_lock(&register_mutex);
-	if (snd_pcm_search(pcm->card, pcm->device)) {
+	err = snd_pcm_add(pcm);
+	if (err) {
 		mutex_unlock(&register_mutex);
-		return -EBUSY;
+		return err;
 	}
-	list_add_tail(&pcm->list, &snd_pcm_devices);
 	for (cidx = 0; cidx < 2; cidx++) {
 		int devtype = -1;
 		if (pcm->streams[cidx].substream == NULL)