[alsa-devel] [PATCH 1/1] ALSA: Fix limit of 8 PCM devices in SNDRV_CTL_IOCTL_PCM_NEXT_DEVICE

Pawel MOLL pawel.moll at st.com
Tue Jul 29 18:34:26 CEST 2008 

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. The same limit was present in OSS emulation code. It has
been fixed as well.

Additionally the device field of struct snd_pcm is now int, instead of
unsigned int, as there is no obvious reason for keeping it unsigned.
This caused a lot of problems with comparing this value with other
(almost always signed) variables. There is just one more place where
device number is unsigned - in struct snd_pcm_info, which should be
also sorted out in future.

Signed-off-by: Pawel MOLL <pawel.moll at st.com>

diff --git a/include/sound/minors.h b/include/sound/minors.h
index 46bcd20..a81798a 100644
--- a/include/sound/minors.h
+++ b/include/sound/minors.h
@@ -21,6 +21,8 @@
  *
  */
 
+#define SNDRV_OS_MINORS			256
+
 #define SNDRV_MINOR_DEVICES		32
 #define SNDRV_MINOR_CARD(minor)		((minor) >> 5)
 #define SNDRV_MINOR_DEVICE(minor)	((minor) & 0x001f)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 51d58cc..bfc096a 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -84,8 +84,6 @@ struct snd_pcm_ops {
  *
  */
 
-#define SNDRV_PCM_DEVICES		8
-
 #define SNDRV_PCM_IOCTL1_FALSE		((void *)0)
 #define SNDRV_PCM_IOCTL1_TRUE		((void *)1)
 
@@ -416,7 +414,7 @@ struct snd_pcm_str {
 struct snd_pcm {
 	struct snd_card *card;
 	struct list_head list;
-	unsigned int device;	/* device number */
+	int device; /* device number */
 	unsigned int info_flags;
 	unsigned short dev_class;
 	unsigned short dev_subclass;
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 4c601b1..4ccd761 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2947,7 +2947,7 @@ static void register_oss_dsp(struct snd_pcm *pcm, int index)
 static int snd_pcm_oss_register_minor(struct snd_pcm *pcm)
 {
 	pcm->oss.reg = 0;
-	if (dsp_map[pcm->card->number] == (int)pcm->device) {
+	if (dsp_map[pcm->card->number] == pcm->device) {
 		char name[128];
 		int duplex;
 		register_oss_dsp(pcm, 0);
@@ -2963,7 +2963,7 @@ static int snd_pcm_oss_register_minor(struct snd_pcm *pcm)
 		pcm->oss.reg++;
 		pcm->oss.reg_mask |= 1;
 	}
-	if (adsp_map[pcm->card->number] == (int)pcm->device) {
+	if (adsp_map[pcm->card->number] == pcm->device) {
 		register_oss_dsp(pcm, 1);
 		pcm->oss.reg++;
 		pcm->oss.reg_mask |= 2;
@@ -2988,7 +2988,7 @@ static int snd_pcm_oss_disconnect_minor(struct snd_pcm *pcm)
 			snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_PCM,
 						  pcm->card, 1);
 		}
-		if (dsp_map[pcm->card->number] == (int)pcm->device) {
+		if (dsp_map[pcm->card->number] == pcm->device) {
 #ifdef SNDRV_OSS_INFO_DEV_AUDIO
 			snd_oss_info_unregister(SNDRV_OSS_INFO_DEV_AUDIO, pcm->card->number);
 #endif
@@ -3019,12 +3019,12 @@ static int __init alsa_pcm_oss_init(void)
 
 	/* check device map table */
 	for (i = 0; i < SNDRV_CARDS; i++) {
-		if (dsp_map[i] < 0 || dsp_map[i] >= SNDRV_PCM_DEVICES) {
+		if (dsp_map[i] < 0 || dsp_map[i] >= SNDRV_OS_MINORS) {
 			snd_printk(KERN_ERR "invalid dsp_map[%d] = %d\n",
 				   i, dsp_map[i]);
 			dsp_map[i] = 0;
 		}
-		if (adsp_map[i] < 0 || adsp_map[i] >= SNDRV_PCM_DEVICES) {
+		if (adsp_map[i] < 0 || adsp_map[i] >= SNDRV_OS_MINORS) {
 			snd_printk(KERN_ERR "invalid adsp_map[%d] = %d\n",
 				   i, adsp_map[i]);
 			adsp_map[i] = 1;
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 9dd9bc7..df4c8a3 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 inline 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 inline 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 inline 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)
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 1003ae3..838dd9e 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -34,8 +34,6 @@
 #include <linux/kmod.h>
 #include <linux/mutex.h>
 
-#define SNDRV_OS_MINORS 256
-
 static int major = CONFIG_SND_MAJOR;
 int snd_major;
 EXPORT_SYMBOL(snd_major);
-- 
1.5.5.1

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