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[ALSA] dynamic minors (4/6): dynamic minor number allocation

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Modules: ALSA Core,ALSA Minor Numbers

Add an option to allocate device file minor numbers dynamically.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
This commit is contained in:
Clemens Ladisch
2005-11-20 14:07:47 +01:00
committed by Jaroslav Kysela
parent f87135f56c
commit 332682b1cd
3 changed files with 86 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
sound/core/Kconfig
View File

@@ -111,6 +111,17 @@ config SND_SEQ_RTCTIMER_DEFAULT
If in doubt, say Y.
config SND_DYNAMIC_MINORS
bool "Dynamic device file minor numbers (EXPERIMENTAL)"
depends on SND && EXPERIMENTAL
help
If you say Y here, the minor numbers of ALSA device files in
/dev/snd/ are allocated dynamically. This allows you to have
more than 8 sound cards, but requires a dynamic device file
system like udev.
If you are unsure about this, say N here.
config SND_VERBOSE_PRINTK
bool "Verbose printk"
depends on SND

73
sound/core/sound.c
View File

@@ -133,29 +133,34 @@ void *snd_lookup_minor_data(unsigned int minor, int type)
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 @@ static struct file_operations snd_fops =
.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 @@ static int snd_kernel_minor(int type, struct snd_card *card, int dev)
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 @@ int snd_register_device(int type, struct snd_card *card, int dev,
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 @@ int snd_register_device(int type, struct snd_card *card, int dev,
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)