cregit-Linux how code gets into the kernel

Release 4.14 sound/sound_core.c

Directory: sound
/*
 *      Sound core.  This file is composed of two parts.  sound_class
 *      which is common to both OSS and ALSA and OSS sound core which
 *      is used OSS or emulation of it.
 */

/*
 * First, the common part.
 */
#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/kdev_t.h>
#include <linux/major.h>
#include <sound/core.h>

#ifdef CONFIG_SOUND_OSS_CORE
static int __init init_oss_soundcore(void);
static void cleanup_oss_soundcore(void);
#else

static inline int init_oss_soundcore(void) { return 0; }

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Tejun Heo12100.00%1100.00%
Total12100.00%1100.00%


static inline void cleanup_oss_soundcore(void) { }

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Tejun Heo8100.00%1100.00%
Total8100.00%1100.00%

#endif struct class *sound_class; EXPORT_SYMBOL(sound_class); MODULE_DESCRIPTION("Core sound module"); MODULE_AUTHOR("Alan Cox"); MODULE_LICENSE("GPL");
static char *sound_devnode(struct device *dev, umode_t *mode) { if (MAJOR(dev->devt) == SOUND_MAJOR) return NULL; return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev)); }

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Kay Sievers4297.67%375.00%
Al Viro12.33%125.00%
Total43100.00%4100.00%


static int __init init_soundcore(void) { int rc; rc = init_oss_soundcore(); if (rc) return rc; sound_class = class_create(THIS_MODULE, "sound"); if (IS_ERR(sound_class)) { cleanup_oss_soundcore(); return PTR_ERR(sound_class); } sound_class->devnode = sound_devnode; return 0; }

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Tejun Heo5490.00%133.33%
Kay Sievers610.00%266.67%
Total60100.00%3100.00%


static void __exit cleanup_soundcore(void) { cleanup_oss_soundcore(); class_destroy(sound_class); }

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Tejun Heo17100.00%1100.00%
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subsys_initcall(init_soundcore); module_exit(cleanup_soundcore); #ifdef CONFIG_SOUND_OSS_CORE /* * OSS sound core handling. Breaks out sound functions to submodules * * Author: Alan Cox <alan@lxorguk.ukuu.org.uk> * * Fixes: * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * -------------------- * * Top level handler for the sound subsystem. Various devices can * plug into this. The fact they don't all go via OSS doesn't mean * they don't have to implement the OSS API. There is a lot of logic * to keeping much of the OSS weight out of the code in a compatibility * module, but it's up to the driver to rember to load it... * * The code provides a set of functions for registration of devices * by type. This is done rather than providing a single call so that * we can hide any future changes in the internals (eg when we go to * 32bit dev_t) from the modules and their interface. * * Secondly we need to allocate the dsp, dsp16 and audio devices as * one. Thus we misuse the chains a bit to simplify this. * * Thirdly to make it more fun and for 2.3.x and above we do all * of this using fine grained locking. * * FIXME: we have to resolve modules and fine grained load/unload * locking at some point in 2.3.x. */ #include <linux/init.h> #include <linux/slab.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/sound.h> #include <linux/kmod.h> #define SOUND_STEP 16 struct sound_unit { int unit_minor; const struct file_operations *unit_fops; struct sound_unit *next; char name[32]; }; #ifdef CONFIG_SOUND_MSNDCLAS extern int msnd_classic_init(void); #endif #ifdef CONFIG_SOUND_MSNDPIN extern int msnd_pinnacle_init(void); #endif /* * By default, OSS sound_core claims full legacy minor range (0-255) * of SOUND_MAJOR to trap open attempts to any sound minor and * requests modules using custom sound-slot/service-* module aliases. * The only benefit of doing this is allowing use of custom module * aliases instead of the standard char-major-* ones. This behavior * prevents alternative OSS implementation and is scheduled to be * removed. * * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel * parameter are added to allow distros and developers to try and * switch to alternative implementations without needing to rebuild * the kernel in the meantime. If preclaim_oss is non-zero, the * kernel will behave the same as before. All SOUND_MAJOR minors are * preclaimed and the custom module aliases along with standard chrdev * ones are emitted if a missing device is opened. If preclaim_oss is * zero, sound_core only grabs what's actually in use and for missing * devices only the standard chrdev aliases are requested. * * All these clutters are scheduled to be removed along with * sound-slot/service-* module aliases. */ #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM static int preclaim_oss = 1; #else static int preclaim_oss = 0; #endif module_param(preclaim_oss, int, 0444); static int soundcore_open(struct inode *, struct file *); static const struct file_operations soundcore_fops = { /* We must have an owner or the module locking fails */ .owner = THIS_MODULE, .open = soundcore_open, .llseek = noop_llseek, }; /* * Low level list operator. Scan the ordered list, find a hole and * join into it. Called with the lock asserted */
static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top) { int n=low; if (index < 0) { /* first free */ while (*list && (*list)->unit_minor<n) list=&((*list)->next); while(n<top) { /* Found a hole ? */ if(*list==NULL || (*list)->unit_minor>n) break; list=&((*list)->next); n+=SOUND_STEP; } if(n>=top) return -ENOENT; } else { n = low+(index*16); while (*list) { if ((*list)->unit_minor==n) return -EBUSY; if ((*list)->unit_minor>n) break; list=&((*list)->next); } } /* * Fill it in */ s->unit_minor=n; s->unit_fops=fops; /* * Link it */ s->next=*list; *list=s; return n; }

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Linus Torvalds (pre-git)21199.53%480.00%
Arjan van de Ven10.47%120.00%
Total212100.00%5100.00%

/* * Remove a node from the chain. Called with the lock asserted */
static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit) { while(*list) { struct sound_unit *p=*list; if(p->unit_minor==unit) { *list=p->next; return p; } list=&(p->next); } printk(KERN_ERR "Sound device %d went missing!\n", unit); return NULL; }

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Linus Torvalds (pre-git)6488.89%150.00%
Jaroslav Kysela811.11%150.00%
Total72100.00%2100.00%

/* * This lock guards the sound loader list. */ static DEFINE_SPINLOCK(sound_loader_lock); /* * Allocate the controlling structure and add it to the sound driver * list. Acquires locks as needed */
static int sound_insert_unit(struct sound_unit **list, const struct file_operations *fops, int index, int low, int top, const char *name, umode_t mode, struct device *dev) { struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL); int r; if (!s) return -ENOMEM; spin_lock(&sound_loader_lock); retry: r = __sound_insert_unit(s, list, fops, index, low, top); spin_unlock(&sound_loader_lock); if (r < 0) goto fail; else if (r < SOUND_STEP) sprintf(s->name, "sound/%s", name); else sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP); if (!preclaim_oss) { /* * Something else might have grabbed the minor. If * first free slot is requested, rescan with @low set * to the next unit; otherwise, -EBUSY. */ r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name, &soundcore_fops); if (r < 0) { spin_lock(&sound_loader_lock); __sound_remove_unit(list, s->unit_minor); if (index < 0) { low = s->unit_minor + SOUND_STEP; goto retry; } spin_unlock(&sound_loader_lock); return -EBUSY; } } device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor), NULL, "%s", s->name+6); return s->unit_minor; fail: kfree(s); return r; }

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Linus Torvalds (pre-git)11744.49%425.00%
Tejun Heo8532.32%16.25%
Christoph Hellwig259.51%16.25%
Greg Kroah-Hartman249.13%531.25%
Takashi Iwai51.90%16.25%
Al Viro20.76%16.25%
Jaroslav Kysela20.76%16.25%
Kees Cook20.76%16.25%
Arjan van de Ven10.38%16.25%
Total263100.00%16100.00%

/* * Remove a unit. Acquires locks as needed. The drivers MUST have * completed the removal before their file operations become * invalid. */
static void sound_remove_unit(struct sound_unit **list, int unit) { struct sound_unit *p; spin_lock(&sound_loader_lock); p = __sound_remove_unit(list, unit); spin_unlock(&sound_loader_lock); if (p) { if (!preclaim_oss) __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1, p->name); device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor)); kfree(p); } }

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Linus Torvalds (pre-git)3439.53%116.67%
Tejun Heo2023.26%116.67%
Jaroslav Kysela1820.93%116.67%
Greg Kroah-Hartman1416.28%350.00%
Total86100.00%6100.00%

/* * Allocations * * 0 *16 Mixers * 1 *8 Sequencers * 2 *16 Midi * 3 *16 DSP * 4 *16 SunDSP * 5 *16 DSP16 * 6 -- sndstat (obsolete) * 7 *16 unused * 8 -- alternate sequencer (see above) * 9 *16 raw synthesizer access * 10 *16 unused * 11 *16 unused * 12 *16 unused * 13 *16 unused * 14 *16 unused * 15 *16 unused */ static struct sound_unit *chains[SOUND_STEP]; /** * register_sound_special_device - register a special sound node * @fops: File operations for the driver * @unit: Unit number to allocate * @dev: device pointer * * Allocate a special sound device by minor number from the sound * subsystem. * * Return: The allocated number is returned on success. On failure, * a negative error code is returned. */
int register_sound_special_device(const struct file_operations *fops, int unit, struct device *dev) { const int chain = unit % SOUND_STEP; int max_unit = 256; const char *name; char _name[16]; switch (chain) { case 0: name = "mixer"; break; case 1: name = "sequencer"; if (unit >= SOUND_STEP) goto __unknown; max_unit = unit + 1; break; case 2: name = "midi"; break; case 3: name = "dsp"; break; case 4: name = "audio"; break; case 5: name = "dspW"; break; case 8: name = "sequencer2"; if (unit >= SOUND_STEP) goto __unknown; max_unit = unit + 1; break; case 9: name = "dmmidi"; break; case 10: name = "dmfm"; break; case 12: name = "adsp"; break; case 13: name = "amidi"; break; case 14: name = "admmidi"; break; default: { __unknown: sprintf(_name, "unknown%d", chain); if (unit >= SOUND_STEP) strcat(_name, "-"); name = _name; } break; } return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit, name, S_IRUSR | S_IWUSR, dev); }

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Linus Torvalds (pre-git)13256.41%440.00%
Jaroslav Kysela8134.62%220.00%
Takashi Iwai208.55%330.00%
Arjan van de Ven10.43%110.00%
Total234100.00%10100.00%

EXPORT_SYMBOL(register_sound_special_device);
int register_sound_special(const struct file_operations *fops, int unit) { return register_sound_special_device(fops, unit, NULL); }

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Takashi Iwai2083.33%133.33%
Linus Torvalds (pre-git)312.50%133.33%
Arjan van de Ven14.17%133.33%
Total24100.00%3100.00%

EXPORT_SYMBOL(register_sound_special); /** * register_sound_mixer - register a mixer device * @fops: File operations for the driver * @dev: Unit number to allocate * * Allocate a mixer device. Unit is the number of the mixer requested. * Pass -1 to request the next free mixer unit. * * Return: On success, the allocated number is returned. On failure, * a negative error code is returned. */
int register_sound_mixer(const struct file_operations *fops, int dev) { return sound_insert_unit(&chains[0], fops, dev, 0, 128, "mixer", S_IRUSR | S_IWUSR, NULL); }

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Linus Torvalds (pre-git)3792.50%466.67%
Takashi Iwai25.00%116.67%
Arjan van de Ven12.50%116.67%
Total40100.00%6100.00%

EXPORT_SYMBOL(register_sound_mixer); /** * register_sound_midi - register a midi device * @fops: File operations for the driver * @dev: Unit number to allocate * * Allocate a midi device. Unit is the number of the midi device requested. * Pass -1 to request the next free midi unit. * * Return: On success, the allocated number is returned. On failure, * a negative error code is returned. */
int register_sound_midi(const struct file_operations *fops, int dev) { return sound_insert_unit(&chains[2], fops, dev, 2, 130, "midi", S_IRUSR | S_IWUSR, NULL); }

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Linus Torvalds (pre-git)3792.50%466.67%
Takashi Iwai25.00%116.67%
Arjan van de Ven12.50%116.67%
Total40100.00%6100.00%

EXPORT_SYMBOL(register_sound_midi); /* * DSP's are registered as a triple. Register only one and cheat * in open - see below. */ /** * register_sound_dsp - register a DSP device * @fops: File operations for the driver * @dev: Unit number to allocate * * Allocate a DSP device. Unit is the number of the DSP requested. * Pass -1 to request the next free DSP unit. * * This function allocates both the audio and dsp device entries together * and will always allocate them as a matching pair - eg dsp3/audio3 * * Return: On success, the allocated number is returned. On failure, * a negative error code is returned. */
int register_sound_dsp(const struct file_operations *fops, int dev) { return sound_insert_unit(&chains[3], fops, dev, 3, 131, "dsp", S_IWUSR | S_IRUSR, NULL); }

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Linus Torvalds (pre-git)3792.50%466.67%
Takashi Iwai25.00%116.67%
Arjan van de Ven12.50%116.67%
Total40100.00%6100.00%

EXPORT_SYMBOL(register_sound_dsp); /** * unregister_sound_special - unregister a special sound device * @unit: unit number to allocate * * Release a sound device that was allocated with * register_sound_special(). The unit passed is the return value from * the register function. */
void unregister_sound_special(int unit) { sound_remove_unit(&chains[unit % SOUND_STEP], unit); }

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Linus Torvalds (pre-git)1990.48%150.00%
Jaroslav Kysela29.52%150.00%
Total21100.00%2100.00%

EXPORT_SYMBOL(unregister_sound_special); /** * unregister_sound_mixer - unregister a mixer * @unit: unit number to allocate * * Release a sound device that was allocated with register_sound_mixer(). * The unit passed is the return value from the register function. */
void unregister_sound_mixer(int unit) { sound_remove_unit(&chains[0], unit); }

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Linus Torvalds (pre-git)19100.00%1100.00%
Total19100.00%1100.00%

EXPORT_SYMBOL(unregister_sound_mixer); /** * unregister_sound_midi - unregister a midi device * @unit: unit number to allocate * * Release a sound device that was allocated with register_sound_midi(). * The unit passed is the return value from the register function. */
void unregister_sound_midi(int unit) { sound_remove_unit(&chains[2], unit); }

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Linus Torvalds (pre-git)1894.74%150.00%
Hannes Eder15.26%150.00%
Total19100.00%2100.00%

EXPORT_SYMBOL(unregister_sound_midi); /** * unregister_sound_dsp - unregister a DSP device * @unit: unit number to allocate * * Release a sound device that was allocated with register_sound_dsp(). * The unit passed is the return value from the register function. * * Both of the allocated units are released together automatically. */
void unregister_sound_dsp(int unit) { sound_remove_unit(&chains[3], unit); }

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Linus Torvalds (pre-git)1894.74%150.00%
Hannes Eder15.26%150.00%
Total19100.00%2100.00%

EXPORT_SYMBOL(unregister_sound_dsp);
static struct sound_unit *__look_for_unit(int chain, int unit) { struct sound_unit *s; s=chains[chain]; while(s && s->unit_minor <= unit) { if(s->unit_minor==unit) return s; s=s->next; } return NULL; }

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Linus Torvalds (pre-git)58100.00%1100.00%
Total58100.00%1100.00%


static int soundcore_open(struct inode *inode, struct file *file) { int chain; int unit = iminor(inode); struct sound_unit *s; const struct file_operations *new_fops = NULL; chain=unit&0x0F; if(chain==4 || chain==5) /* dsp/audio/dsp16 */ { unit&=0xF0; unit|=3; chain=3; } spin_lock(&sound_loader_lock); s = __look_for_unit(chain, unit); if (s) new_fops = fops_get(s->unit_fops); if (preclaim_oss && !new_fops) { spin_unlock(&sound_loader_lock); /* * Please, don't change this order or code. * For ALSA slot means soundcard and OSS emulation code * comes as add-on modules which aren't depend on * ALSA toplevel modules for soundcards, thus we need * load them at first. [Jaroslav Kysela <perex@jcu.cz>] */ request_module("sound-slot-%i", unit>>4); request_module("sound-service-%i-%i", unit>>4, chain); /* * sound-slot/service-* module aliases are scheduled * for removal in favor of the standard char-major-* * module aliases. For the time being, generate both * the legacy and standard module aliases to ease * transition. */ if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0) request_module("char-major-%d", SOUND_MAJOR); spin_lock(&sound_loader_lock); s = __look_for_unit(chain, unit); if (s) new_fops = fops_get(s->unit_fops); } spin_unlock(&sound_loader_lock); if (new_fops) { /* * We rely upon the fact that we can't be unloaded while the * subdriver is there. */ int err = 0; replace_fops(file, new_fops); if (file->f_op->open) err = file->f_op->open(inode,file); return err; } return -ENODEV; }

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Linus Torvalds (pre-git)20084.39%436.36%
Tejun Heo239.70%218.18%
Al Viro114.64%218.18%
Linus Torvalds10.42%19.09%
Arjan van de Ven10.42%19.09%
Hannes Eder10.42%19.09%
Total237100.00%11100.00%

MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
static void cleanup_oss_soundcore(void) { /* We have nothing to really do here - we know the lists must be empty */ unregister_chrdev(SOUND_MAJOR, "sound"); }

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Linus Torvalds (pre-git)1487.50%250.00%
Greg Kroah-Hartman16.25%125.00%
Tejun Heo16.25%125.00%
Total16100.00%4100.00%


static int __init init_oss_soundcore(void) { if (preclaim_oss && register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) { printk(KERN_ERR "soundcore: sound device already in use.\n"); return -EBUSY; } return 0; }

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Linus Torvalds (pre-git)3485.00%233.33%
Tejun Heo37.50%233.33%
Alexey Khoroshilov25.00%116.67%
Greg Kroah-Hartman12.50%116.67%
Total40100.00%6100.00%

#endif /* CONFIG_SOUND_OSS_CORE */

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Linus Torvalds (pre-git)117662.52%1223.53%
Tejun Heo35518.87%35.88%
Jaroslav Kysela1125.95%35.88%
Takashi Iwai562.98%35.88%
Kay Sievers542.87%35.88%
Greg Kroah-Hartman402.13%713.73%
Christoph Hellwig301.59%11.96%
Al Viro140.74%47.84%
Arjan van de Ven90.48%11.96%
Arnd Bergmann50.27%11.96%
Andrew Morton50.27%11.96%
Yacine Belkadi40.21%11.96%
Thomas Gleixner40.21%11.96%
Mark Brown30.16%11.96%
Hannes Eder30.16%11.96%
Jonathan Corbet20.11%11.96%
Kees Cook20.11%11.96%
Alexey Khoroshilov20.11%11.96%
Linus Torvalds20.11%23.92%
Tao Ma10.05%11.96%
Thadeu Lima de Souza Cascardo10.05%11.96%
Alan Cox10.05%11.96%
Total1881100.00%51100.00%
Directory: sound
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