Immunize rcu_dereference() against crazy compiler writers
[linux-2.6] / sound / core / sound_oss.c
1 /*
2  *  Advanced Linux Sound Architecture
3  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
4  *
5  *
6  *   This program is free software; you can redistribute it and/or modify
7  *   it under the terms of the GNU General Public License as published by
8  *   the Free Software Foundation; either version 2 of the License, or
9  *   (at your option) any later version.
10  *
11  *   This program is distributed in the hope that it will be useful,
12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *   GNU General Public License for more details.
15  *
16  *   You should have received a copy of the GNU General Public License
17  *   along with this program; if not, write to the Free Software
18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
19  *
20  */
21
22 #include <sound/driver.h>
23
24 #ifdef CONFIG_SND_OSSEMUL
25
26 #if !defined(CONFIG_SOUND) && !(defined(MODULE) && defined(CONFIG_SOUND_MODULE))
27 #error "Enable the OSS soundcore multiplexer (CONFIG_SOUND) in the kernel."
28 #endif
29
30 #include <linux/init.h>
31 #include <linux/slab.h>
32 #include <linux/time.h>
33 #include <sound/core.h>
34 #include <sound/minors.h>
35 #include <sound/info.h>
36 #include <linux/sound.h>
37 #include <linux/mutex.h>
38
39 #define SNDRV_OSS_MINORS 128
40
41 static struct snd_minor *snd_oss_minors[SNDRV_OSS_MINORS];
42 static DEFINE_MUTEX(sound_oss_mutex);
43
44 void *snd_lookup_oss_minor_data(unsigned int minor, int type)
45 {
46         struct snd_minor *mreg;
47         void *private_data;
48
49         if (minor >= ARRAY_SIZE(snd_oss_minors))
50                 return NULL;
51         mutex_lock(&sound_oss_mutex);
52         mreg = snd_oss_minors[minor];
53         if (mreg && mreg->type == type)
54                 private_data = mreg->private_data;
55         else
56                 private_data = NULL;
57         mutex_unlock(&sound_oss_mutex);
58         return private_data;
59 }
60
61 EXPORT_SYMBOL(snd_lookup_oss_minor_data);
62
63 static int snd_oss_kernel_minor(int type, struct snd_card *card, int dev)
64 {
65         int minor;
66
67         switch (type) {
68         case SNDRV_OSS_DEVICE_TYPE_MIXER:
69                 snd_assert(card != NULL && dev <= 1, return -EINVAL);
70                 minor = SNDRV_MINOR_OSS(card->number, (dev ? SNDRV_MINOR_OSS_MIXER1 : SNDRV_MINOR_OSS_MIXER));
71                 break;
72         case SNDRV_OSS_DEVICE_TYPE_SEQUENCER:
73                 minor = SNDRV_MINOR_OSS_SEQUENCER;
74                 break;
75         case SNDRV_OSS_DEVICE_TYPE_MUSIC:
76                 minor = SNDRV_MINOR_OSS_MUSIC;
77                 break;
78         case SNDRV_OSS_DEVICE_TYPE_PCM:
79                 snd_assert(card != NULL && dev <= 1, return -EINVAL);
80                 minor = SNDRV_MINOR_OSS(card->number, (dev ? SNDRV_MINOR_OSS_PCM1 : SNDRV_MINOR_OSS_PCM));
81                 break;
82         case SNDRV_OSS_DEVICE_TYPE_MIDI:
83                 snd_assert(card != NULL && dev <= 1, return -EINVAL);
84                 minor = SNDRV_MINOR_OSS(card->number, (dev ? SNDRV_MINOR_OSS_MIDI1 : SNDRV_MINOR_OSS_MIDI));
85                 break;
86         case SNDRV_OSS_DEVICE_TYPE_DMFM:
87                 minor = SNDRV_MINOR_OSS(card->number, SNDRV_MINOR_OSS_DMFM);
88                 break;
89         case SNDRV_OSS_DEVICE_TYPE_SNDSTAT:
90                 minor = SNDRV_MINOR_OSS_SNDSTAT;
91                 break;
92         default:
93                 return -EINVAL;
94         }
95         snd_assert(minor >= 0 && minor < SNDRV_OSS_MINORS, return -EINVAL);
96         return minor;
97 }
98
99 int snd_register_oss_device(int type, struct snd_card *card, int dev,
100                             const struct file_operations *f_ops, void *private_data,
101                             const char *name)
102 {
103         int minor = snd_oss_kernel_minor(type, card, dev);
104         int minor_unit;
105         struct snd_minor *preg;
106         int cidx = SNDRV_MINOR_OSS_CARD(minor);
107         int track2 = -1;
108         int register1 = -1, register2 = -1;
109         struct device *carddev = snd_card_get_device_link(card);
110
111         if (card && card->number >= 8)
112                 return 0; /* ignore silently */
113         if (minor < 0)
114                 return minor;
115         preg = kmalloc(sizeof(struct snd_minor), GFP_KERNEL);
116         if (preg == NULL)
117                 return -ENOMEM;
118         preg->type = type;
119         preg->card = card ? card->number : -1;
120         preg->device = dev;
121         preg->f_ops = f_ops;
122         preg->private_data = private_data;
123         mutex_lock(&sound_oss_mutex);
124         snd_oss_minors[minor] = preg;
125         minor_unit = SNDRV_MINOR_OSS_DEVICE(minor);
126         switch (minor_unit) {
127         case SNDRV_MINOR_OSS_PCM:
128                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_AUDIO);
129                 break;
130         case SNDRV_MINOR_OSS_MIDI:
131                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_DMMIDI);
132                 break;
133         case SNDRV_MINOR_OSS_MIDI1:
134                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_DMMIDI1);
135                 break;
136         }
137         register1 = register_sound_special_device(f_ops, minor, carddev);
138         if (register1 != minor)
139                 goto __end;
140         if (track2 >= 0) {
141                 register2 = register_sound_special_device(f_ops, track2,
142                                                           carddev);
143                 if (register2 != track2)
144                         goto __end;
145                 snd_oss_minors[track2] = preg;
146         }
147         mutex_unlock(&sound_oss_mutex);
148         return 0;
149
150       __end:
151         if (register2 >= 0)
152                 unregister_sound_special(register2);
153         if (register1 >= 0)
154                 unregister_sound_special(register1);
155         snd_oss_minors[minor] = NULL;
156         mutex_unlock(&sound_oss_mutex);
157         kfree(preg);
158         return -EBUSY;
159 }
160
161 EXPORT_SYMBOL(snd_register_oss_device);
162
163 int snd_unregister_oss_device(int type, struct snd_card *card, int dev)
164 {
165         int minor = snd_oss_kernel_minor(type, card, dev);
166         int cidx = SNDRV_MINOR_OSS_CARD(minor);
167         int track2 = -1;
168         struct snd_minor *mptr;
169
170         if (card && card->number >= 8)
171                 return 0;
172         if (minor < 0)
173                 return minor;
174         mutex_lock(&sound_oss_mutex);
175         mptr = snd_oss_minors[minor];
176         if (mptr == NULL) {
177                 mutex_unlock(&sound_oss_mutex);
178                 return -ENOENT;
179         }
180         unregister_sound_special(minor);
181         switch (SNDRV_MINOR_OSS_DEVICE(minor)) {
182         case SNDRV_MINOR_OSS_PCM:
183                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_AUDIO);
184                 break;
185         case SNDRV_MINOR_OSS_MIDI:
186                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_DMMIDI);
187                 break;
188         case SNDRV_MINOR_OSS_MIDI1:
189                 track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_DMMIDI1);
190                 break;
191         }
192         if (track2 >= 0) {
193                 unregister_sound_special(track2);
194                 snd_oss_minors[track2] = NULL;
195         }
196         snd_oss_minors[minor] = NULL;
197         mutex_unlock(&sound_oss_mutex);
198         kfree(mptr);
199         return 0;
200 }
201
202 EXPORT_SYMBOL(snd_unregister_oss_device);
203
204 /*
205  *  INFO PART
206  */
207
208 #ifdef CONFIG_PROC_FS
209
210 static struct snd_info_entry *snd_minor_info_oss_entry;
211
212 static const char *snd_oss_device_type_name(int type)
213 {
214         switch (type) {
215         case SNDRV_OSS_DEVICE_TYPE_MIXER:
216                 return "mixer";
217         case SNDRV_OSS_DEVICE_TYPE_SEQUENCER:
218         case SNDRV_OSS_DEVICE_TYPE_MUSIC:
219                 return "sequencer";
220         case SNDRV_OSS_DEVICE_TYPE_PCM:
221                 return "digital audio";
222         case SNDRV_OSS_DEVICE_TYPE_MIDI:
223                 return "raw midi";
224         case SNDRV_OSS_DEVICE_TYPE_DMFM:
225                 return "hardware dependent";
226         default:
227                 return "?";
228         }
229 }
230
231 static void snd_minor_info_oss_read(struct snd_info_entry *entry,
232                                     struct snd_info_buffer *buffer)
233 {
234         int minor;
235         struct snd_minor *mptr;
236
237         mutex_lock(&sound_oss_mutex);
238         for (minor = 0; minor < SNDRV_OSS_MINORS; ++minor) {
239                 if (!(mptr = snd_oss_minors[minor]))
240                         continue;
241                 if (mptr->card >= 0)
242                         snd_iprintf(buffer, "%3i: [%i-%2i]: %s\n", minor,
243                                     mptr->card, mptr->device,
244                                     snd_oss_device_type_name(mptr->type));
245                 else
246                         snd_iprintf(buffer, "%3i:       : %s\n", minor,
247                                     snd_oss_device_type_name(mptr->type));
248         }
249         mutex_unlock(&sound_oss_mutex);
250 }
251
252
253 int __init snd_minor_info_oss_init(void)
254 {
255         struct snd_info_entry *entry;
256
257         entry = snd_info_create_module_entry(THIS_MODULE, "devices", snd_oss_root);
258         if (entry) {
259                 entry->c.text.read = snd_minor_info_oss_read;
260                 if (snd_info_register(entry) < 0) {
261                         snd_info_free_entry(entry);
262                         entry = NULL;
263                 }
264         }
265         snd_minor_info_oss_entry = entry;
266         return 0;
267 }
268
269 int __exit snd_minor_info_oss_done(void)
270 {
271         snd_info_free_entry(snd_minor_info_oss_entry);
272         return 0;
273 }
274 #endif /* CONFIG_PROC_FS */
275
276 #endif /* CONFIG_SND_OSSEMUL */