[ALSA] dynamic minors (4/6): dynamic minor number allocation
Modules: ALSA Core,ALSA Minor Numbers
Add an option to allocate device file minor numbers dynamically.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 1e5eca5..5e22283 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -133,29 +133,34 @@
static int snd_open(struct inode *inode, struct file *file)
{
- int minor = iminor(inode);
- int card = SNDRV_MINOR_CARD(minor);
- int dev = SNDRV_MINOR_DEVICE(minor);
+ unsigned int minor = iminor(inode);
struct snd_minor *mptr = NULL;
struct file_operations *old_fops;
int err = 0;
- if (dev != SNDRV_MINOR_GLOBAL) {
- if (snd_cards[card] == NULL) {
-#ifdef CONFIG_KMOD
- snd_request_card(card);
- if (snd_cards[card] == NULL)
-#endif
- return -ENODEV;
- }
- } else {
-#ifdef CONFIG_KMOD
- if ((mptr = snd_minors[minor]) == NULL)
- snd_request_other(minor);
-#endif
- }
- if (mptr == NULL && (mptr = snd_minors[minor]) == NULL)
+ if (minor > ARRAY_SIZE(snd_minors))
return -ENODEV;
+ mptr = snd_minors[minor];
+ if (mptr == NULL) {
+#ifdef CONFIG_KMOD
+ int dev = SNDRV_MINOR_DEVICE(minor);
+ if (dev == SNDRV_MINOR_CONTROL) {
+ /* /dev/aloadC? */
+ int card = SNDRV_MINOR_CARD(minor);
+ if (snd_cards[card] == NULL)
+ snd_request_card(card);
+ } else if (dev == SNDRV_MINOR_GLOBAL) {
+ /* /dev/aloadSEQ */
+ snd_request_other(minor);
+ }
+#ifndef CONFIG_SND_DYNAMIC_MINORS
+ /* /dev/snd/{controlC?,seq} */
+ mptr = snd_minors[minor];
+ if (mptr == NULL)
+#endif
+#endif
+ return -ENODEV;
+ }
old_fops = file->f_op;
file->f_op = fops_get(mptr->f_ops);
if (file->f_op->open)
@@ -174,6 +179,22 @@
.open = snd_open
};
+#ifdef CONFIG_SND_DYNAMIC_MINORS
+static int snd_find_free_minor(void)
+{
+ int minor;
+
+ for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
+ /* skip minors still used statically for autoloading devices */
+ if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL ||
+ minor == SNDRV_MINOR_SEQUENCER)
+ continue;
+ if (!snd_minors[minor])
+ return minor;
+ }
+ return -EBUSY;
+}
+#else
static int snd_kernel_minor(int type, struct snd_card *card, int dev)
{
int minor;
@@ -200,6 +221,7 @@
snd_assert(minor >= 0 && minor < SNDRV_OS_MINORS, return -EINVAL);
return minor;
}
+#endif
/**
* snd_register_device - Register the ALSA device file for the card
@@ -219,12 +241,10 @@
struct file_operations *f_ops, void *private_data,
const char *name)
{
- int minor = snd_kernel_minor(type, card, dev);
+ int minor;
struct snd_minor *preg;
struct device *device = NULL;
- if (minor < 0)
- return minor;
snd_assert(name, return -EINVAL);
preg = kmalloc(sizeof(struct snd_minor) + strlen(name) + 1, GFP_KERNEL);
if (preg == NULL)
@@ -236,10 +256,17 @@
preg->private_data = private_data;
strcpy(preg->name, name);
down(&sound_mutex);
- if (snd_minors[minor]) {
+#ifdef CONFIG_SND_DYNAMIC_MINORS
+ minor = snd_find_free_minor();
+#else
+ minor = snd_kernel_minor(type, card, dev);
+ if (minor >= 0 && snd_minors[minor])
+ minor = -EBUSY;
+#endif
+ if (minor < 0) {
up(&sound_mutex);
kfree(preg);
- return -EBUSY;
+ return minor;
}
snd_minors[minor] = preg;
if (type != SNDRV_DEVICE_TYPE_CONTROL || preg->card >= cards_limit)