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Merge branch 'topic/soundcore-preclaim' into for-linus
* topic/soundcore-preclaim: sound: make OSS device number claiming optional and schedule its removal sound: request char-major-* module aliases for missing OSS devices chrdev: implement __[un]register_chrdev()
This commit is contained in:
Takashi Iwai
commit
3827119e20
5 changed files with 176 additions and 34 deletions
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@ -32,6 +32,34 @@ config SOUND_OSS_CORE
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bool
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default n
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config SOUND_OSS_CORE_PRECLAIM
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bool "Preclaim OSS device numbers"
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depends on SOUND_OSS_CORE
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default y
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help
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With this option enabled, the kernel will claim all OSS device
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numbers if any OSS support (native or emulation) is enabled
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whether the respective module is loaded or not and try to load the
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appropriate module using sound-slot/service-* and char-major-*
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module aliases when one of the device numbers is opened. With
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this option disabled, kernel will only claim actually in-use
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device numbers and opening a missing device will generate only the
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standard char-major-* aliases.
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The only visible difference is use of additional module aliases
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and whether OSS sound devices appear multiple times in
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/proc/devices. sound-slot/service-* module aliases are scheduled
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to be removed (ie. PRECLAIM won't be available) and this option is
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to make the transition easier. This option can be overridden
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during boot using the kernel parameter soundcore.preclaim_oss.
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Disabling this allows alternative OSS implementations.
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Please read Documentation/feature-removal-schedule.txt for
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details.
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If unusre, say Y.
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source "sound/oss/dmasound/Kconfig"
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if !M68K
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@ -127,6 +127,46 @@ extern int msnd_classic_init(void);
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extern int msnd_pinnacle_init(void);
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#endif
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/*
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* By default, OSS sound_core claims full legacy minor range (0-255)
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* of SOUND_MAJOR to trap open attempts to any sound minor and
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* requests modules using custom sound-slot/service-* module aliases.
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* The only benefit of doing this is allowing use of custom module
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* aliases instead of the standard char-major-* ones. This behavior
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* prevents alternative OSS implementation and is scheduled to be
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* removed.
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*
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* CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
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* parameter are added to allow distros and developers to try and
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* switch to alternative implementations without needing to rebuild
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* the kernel in the meantime. If preclaim_oss is non-zero, the
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* kernel will behave the same as before. All SOUND_MAJOR minors are
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* preclaimed and the custom module aliases along with standard chrdev
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* ones are emitted if a missing device is opened. If preclaim_oss is
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* zero, sound_core only grabs what's actually in use and for missing
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* devices only the standard chrdev aliases are requested.
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*
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* All these clutters are scheduled to be removed along with
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* sound-slot/service-* module aliases. Please take a look at
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* feature-removal-schedule.txt for details.
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*/
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#ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
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static int preclaim_oss = 1;
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#else
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static int preclaim_oss = 0;
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#endif
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module_param(preclaim_oss, int, 0444);
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static int soundcore_open(struct inode *, struct file *);
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static const struct file_operations soundcore_fops =
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{
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/* We must have an owner or the module locking fails */
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.owner = THIS_MODULE,
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.open = soundcore_open,
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};
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/*
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* Low level list operator. Scan the ordered list, find a hole and
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* join into it. Called with the lock asserted
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@ -219,8 +259,9 @@ static int sound_insert_unit(struct sound_unit **list, const struct file_operati
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if (!s)
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return -ENOMEM;
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spin_lock(&sound_loader_lock);
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retry:
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r = __sound_insert_unit(s, list, fops, index, low, top);
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spin_unlock(&sound_loader_lock);
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@ -231,11 +272,31 @@ static int sound_insert_unit(struct sound_unit **list, const struct file_operati
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else
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sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
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if (!preclaim_oss) {
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/*
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* Something else might have grabbed the minor. If
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* first free slot is requested, rescan with @low set
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* to the next unit; otherwise, -EBUSY.
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*/
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r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
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&soundcore_fops);
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if (r < 0) {
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spin_lock(&sound_loader_lock);
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__sound_remove_unit(list, s->unit_minor);
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if (index < 0) {
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low = s->unit_minor + SOUND_STEP;
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goto retry;
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}
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spin_unlock(&sound_loader_lock);
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return -EBUSY;
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}
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}
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device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
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NULL, s->name+6);
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return r;
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return s->unit_minor;
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fail:
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fail:
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kfree(s);
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return r;
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}
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@ -254,6 +315,9 @@ static void sound_remove_unit(struct sound_unit **list, int unit)
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p = __sound_remove_unit(list, unit);
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spin_unlock(&sound_loader_lock);
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if (p) {
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if (!preclaim_oss)
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__unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
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p->name);
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device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
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kfree(p);
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}
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@ -491,19 +555,6 @@ void unregister_sound_dsp(int unit)
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EXPORT_SYMBOL(unregister_sound_dsp);
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/*
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* Now our file operations
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*/
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static int soundcore_open(struct inode *, struct file *);
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static const struct file_operations soundcore_fops=
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{
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/* We must have an owner or the module locking fails */
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.owner = THIS_MODULE,
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.open = soundcore_open,
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};
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static struct sound_unit *__look_for_unit(int chain, int unit)
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{
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struct sound_unit *s;
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@ -539,8 +590,9 @@ static int soundcore_open(struct inode *inode, struct file *file)
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s = __look_for_unit(chain, unit);
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if (s)
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new_fops = fops_get(s->unit_fops);
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if (!new_fops) {
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if (preclaim_oss && !new_fops) {
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spin_unlock(&sound_loader_lock);
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/*
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* Please, don't change this order or code.
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* For ALSA slot means soundcard and OSS emulation code
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@ -550,6 +602,17 @@ static int soundcore_open(struct inode *inode, struct file *file)
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*/
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request_module("sound-slot-%i", unit>>4);
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request_module("sound-service-%i-%i", unit>>4, chain);
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/*
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* sound-slot/service-* module aliases are scheduled
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* for removal in favor of the standard char-major-*
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* module aliases. For the time being, generate both
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* the legacy and standard module aliases to ease
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* transition.
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*/
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if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
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request_module("char-major-%d", SOUND_MAJOR);
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spin_lock(&sound_loader_lock);
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s = __look_for_unit(chain, unit);
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if (s)
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@ -593,7 +656,8 @@ static void cleanup_oss_soundcore(void)
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static int __init init_oss_soundcore(void)
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{
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if (register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops)==-1) {
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if (preclaim_oss &&
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register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
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printk(KERN_ERR "soundcore: sound device already in use.\n");
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return -EBUSY;
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}
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