[ALSA] Add snd-als300 driver for Avance Logic ALS300/ALS300+ soundcards
[linux-2.6.22.y-op.git] / ipc / util.c
blob23151ef3259030d00b6fee264edf2f42e80e0560
1 /*
2 * linux/ipc/util.c
3 * Copyright (C) 1992 Krishna Balasubramanian
5 * Sep 1997 - Call suser() last after "normal" permission checks so we
6 * get BSD style process accounting right.
7 * Occurs in several places in the IPC code.
8 * Chris Evans, <chris@ferret.lmh.ox.ac.uk>
9 * Nov 1999 - ipc helper functions, unified SMP locking
10 * Manfred Spraul <manfred@colorfullife.com>
11 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
12 * Mingming Cao <cmm@us.ibm.com>
15 #include <linux/config.h>
16 #include <linux/mm.h>
17 #include <linux/shm.h>
18 #include <linux/init.h>
19 #include <linux/msg.h>
20 #include <linux/smp_lock.h>
21 #include <linux/vmalloc.h>
22 #include <linux/slab.h>
23 #include <linux/capability.h>
24 #include <linux/highuid.h>
25 #include <linux/security.h>
26 #include <linux/rcupdate.h>
27 #include <linux/workqueue.h>
28 #include <linux/seq_file.h>
29 #include <linux/proc_fs.h>
31 #include <asm/unistd.h>
33 #include "util.h"
35 struct ipc_proc_iface {
36 const char *path;
37 const char *header;
38 struct ipc_ids *ids;
39 int (*show)(struct seq_file *, void *);
42 /**
43 * ipc_init - initialise IPC subsystem
45 * The various system5 IPC resources (semaphores, messages and shared
46 * memory are initialised
49 static int __init ipc_init(void)
51 sem_init();
52 msg_init();
53 shm_init();
54 return 0;
56 __initcall(ipc_init);
58 /**
59 * ipc_init_ids - initialise IPC identifiers
60 * @ids: Identifier set
61 * @size: Number of identifiers
63 * Given a size for the ipc identifier range (limited below IPCMNI)
64 * set up the sequence range to use then allocate and initialise the
65 * array itself.
68 void __init ipc_init_ids(struct ipc_ids* ids, int size)
70 int i;
72 mutex_init(&ids->mutex);
74 if(size > IPCMNI)
75 size = IPCMNI;
76 ids->in_use = 0;
77 ids->max_id = -1;
78 ids->seq = 0;
80 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
81 if(seq_limit > USHRT_MAX)
82 ids->seq_max = USHRT_MAX;
83 else
84 ids->seq_max = seq_limit;
87 ids->entries = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*size +
88 sizeof(struct ipc_id_ary));
90 if(ids->entries == NULL) {
91 printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
92 size = 0;
93 ids->entries = &ids->nullentry;
95 ids->entries->size = size;
96 for(i=0;i<size;i++)
97 ids->entries->p[i] = NULL;
100 #ifdef CONFIG_PROC_FS
101 static struct file_operations sysvipc_proc_fops;
103 * ipc_init_proc_interface - Create a proc interface for sysipc types
104 * using a seq_file interface.
105 * @path: Path in procfs
106 * @header: Banner to be printed at the beginning of the file.
107 * @ids: ipc id table to iterate.
108 * @show: show routine.
110 void __init ipc_init_proc_interface(const char *path, const char *header,
111 struct ipc_ids *ids,
112 int (*show)(struct seq_file *, void *))
114 struct proc_dir_entry *pde;
115 struct ipc_proc_iface *iface;
117 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
118 if (!iface)
119 return;
120 iface->path = path;
121 iface->header = header;
122 iface->ids = ids;
123 iface->show = show;
125 pde = create_proc_entry(path,
126 S_IRUGO, /* world readable */
127 NULL /* parent dir */);
128 if (pde) {
129 pde->data = iface;
130 pde->proc_fops = &sysvipc_proc_fops;
131 } else {
132 kfree(iface);
135 #endif
138 * ipc_findkey - find a key in an ipc identifier set
139 * @ids: Identifier set
140 * @key: The key to find
142 * Requires ipc_ids.mutex locked.
143 * Returns the identifier if found or -1 if not.
146 int ipc_findkey(struct ipc_ids* ids, key_t key)
148 int id;
149 struct kern_ipc_perm* p;
150 int max_id = ids->max_id;
153 * rcu_dereference() is not needed here
154 * since ipc_ids.mutex is held
156 for (id = 0; id <= max_id; id++) {
157 p = ids->entries->p[id];
158 if(p==NULL)
159 continue;
160 if (key == p->key)
161 return id;
163 return -1;
167 * Requires ipc_ids.mutex locked
169 static int grow_ary(struct ipc_ids* ids, int newsize)
171 struct ipc_id_ary* new;
172 struct ipc_id_ary* old;
173 int i;
174 int size = ids->entries->size;
176 if(newsize > IPCMNI)
177 newsize = IPCMNI;
178 if(newsize <= size)
179 return newsize;
181 new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +
182 sizeof(struct ipc_id_ary));
183 if(new == NULL)
184 return size;
185 new->size = newsize;
186 memcpy(new->p, ids->entries->p, sizeof(struct kern_ipc_perm *)*size +
187 sizeof(struct ipc_id_ary));
188 for(i=size;i<newsize;i++) {
189 new->p[i] = NULL;
191 old = ids->entries;
194 * Use rcu_assign_pointer() to make sure the memcpyed contents
195 * of the new array are visible before the new array becomes visible.
197 rcu_assign_pointer(ids->entries, new);
199 ipc_rcu_putref(old);
200 return newsize;
204 * ipc_addid - add an IPC identifier
205 * @ids: IPC identifier set
206 * @new: new IPC permission set
207 * @size: new size limit for the id array
209 * Add an entry 'new' to the IPC arrays. The permissions object is
210 * initialised and the first free entry is set up and the id assigned
211 * is returned. The list is returned in a locked state on success.
212 * On failure the list is not locked and -1 is returned.
214 * Called with ipc_ids.mutex held.
217 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
219 int id;
221 size = grow_ary(ids,size);
224 * rcu_dereference()() is not needed here since
225 * ipc_ids.mutex is held
227 for (id = 0; id < size; id++) {
228 if(ids->entries->p[id] == NULL)
229 goto found;
231 return -1;
232 found:
233 ids->in_use++;
234 if (id > ids->max_id)
235 ids->max_id = id;
237 new->cuid = new->uid = current->euid;
238 new->gid = new->cgid = current->egid;
240 new->seq = ids->seq++;
241 if(ids->seq > ids->seq_max)
242 ids->seq = 0;
244 spin_lock_init(&new->lock);
245 new->deleted = 0;
246 rcu_read_lock();
247 spin_lock(&new->lock);
248 ids->entries->p[id] = new;
249 return id;
253 * ipc_rmid - remove an IPC identifier
254 * @ids: identifier set
255 * @id: Identifier to remove
257 * The identifier must be valid, and in use. The kernel will panic if
258 * fed an invalid identifier. The entry is removed and internal
259 * variables recomputed. The object associated with the identifier
260 * is returned.
261 * ipc_ids.mutex and the spinlock for this ID is hold before this function
262 * is called, and remain locked on the exit.
265 struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
267 struct kern_ipc_perm* p;
268 int lid = id % SEQ_MULTIPLIER;
269 if(lid >= ids->entries->size)
270 BUG();
273 * do not need a rcu_dereference()() here to force ordering
274 * on Alpha, since the ipc_ids.mutex is held.
276 p = ids->entries->p[lid];
277 ids->entries->p[lid] = NULL;
278 if(p==NULL)
279 BUG();
280 ids->in_use--;
282 if (lid == ids->max_id) {
283 do {
284 lid--;
285 if(lid == -1)
286 break;
287 } while (ids->entries->p[lid] == NULL);
288 ids->max_id = lid;
290 p->deleted = 1;
291 return p;
295 * ipc_alloc - allocate ipc space
296 * @size: size desired
298 * Allocate memory from the appropriate pools and return a pointer to it.
299 * NULL is returned if the allocation fails
302 void* ipc_alloc(int size)
304 void* out;
305 if(size > PAGE_SIZE)
306 out = vmalloc(size);
307 else
308 out = kmalloc(size, GFP_KERNEL);
309 return out;
313 * ipc_free - free ipc space
314 * @ptr: pointer returned by ipc_alloc
315 * @size: size of block
317 * Free a block created with ipc_alloc. The caller must know the size
318 * used in the allocation call.
321 void ipc_free(void* ptr, int size)
323 if(size > PAGE_SIZE)
324 vfree(ptr);
325 else
326 kfree(ptr);
330 * rcu allocations:
331 * There are three headers that are prepended to the actual allocation:
332 * - during use: ipc_rcu_hdr.
333 * - during the rcu grace period: ipc_rcu_grace.
334 * - [only if vmalloc]: ipc_rcu_sched.
335 * Their lifetime doesn't overlap, thus the headers share the same memory.
336 * Unlike a normal union, they are right-aligned, thus some container_of
337 * forward/backward casting is necessary:
339 struct ipc_rcu_hdr
341 int refcount;
342 int is_vmalloc;
343 void *data[0];
347 struct ipc_rcu_grace
349 struct rcu_head rcu;
350 /* "void *" makes sure alignment of following data is sane. */
351 void *data[0];
354 struct ipc_rcu_sched
356 struct work_struct work;
357 /* "void *" makes sure alignment of following data is sane. */
358 void *data[0];
361 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
362 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
363 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
364 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
366 static inline int rcu_use_vmalloc(int size)
368 /* Too big for a single page? */
369 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
370 return 1;
371 return 0;
375 * ipc_rcu_alloc - allocate ipc and rcu space
376 * @size: size desired
378 * Allocate memory for the rcu header structure + the object.
379 * Returns the pointer to the object.
380 * NULL is returned if the allocation fails.
383 void* ipc_rcu_alloc(int size)
385 void* out;
387 * We prepend the allocation with the rcu struct, and
388 * workqueue if necessary (for vmalloc).
390 if (rcu_use_vmalloc(size)) {
391 out = vmalloc(HDRLEN_VMALLOC + size);
392 if (out) {
393 out += HDRLEN_VMALLOC;
394 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
395 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
397 } else {
398 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
399 if (out) {
400 out += HDRLEN_KMALLOC;
401 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
402 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
406 return out;
409 void ipc_rcu_getref(void *ptr)
411 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
415 * ipc_schedule_free - free ipc + rcu space
416 * @head: RCU callback structure for queued work
418 * Since RCU callback function is called in bh,
419 * we need to defer the vfree to schedule_work
421 static void ipc_schedule_free(struct rcu_head *head)
423 struct ipc_rcu_grace *grace =
424 container_of(head, struct ipc_rcu_grace, rcu);
425 struct ipc_rcu_sched *sched =
426 container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]);
428 INIT_WORK(&sched->work, vfree, sched);
429 schedule_work(&sched->work);
433 * ipc_immediate_free - free ipc + rcu space
434 * @head: RCU callback structure that contains pointer to be freed
436 * Free from the RCU callback context
438 static void ipc_immediate_free(struct rcu_head *head)
440 struct ipc_rcu_grace *free =
441 container_of(head, struct ipc_rcu_grace, rcu);
442 kfree(free);
445 void ipc_rcu_putref(void *ptr)
447 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
448 return;
450 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
451 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
452 ipc_schedule_free);
453 } else {
454 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
455 ipc_immediate_free);
460 * ipcperms - check IPC permissions
461 * @ipcp: IPC permission set
462 * @flag: desired permission set.
464 * Check user, group, other permissions for access
465 * to ipc resources. return 0 if allowed
468 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
469 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
470 int requested_mode, granted_mode;
472 requested_mode = (flag >> 6) | (flag >> 3) | flag;
473 granted_mode = ipcp->mode;
474 if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
475 granted_mode >>= 6;
476 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
477 granted_mode >>= 3;
478 /* is there some bit set in requested_mode but not in granted_mode? */
479 if ((requested_mode & ~granted_mode & 0007) &&
480 !capable(CAP_IPC_OWNER))
481 return -1;
483 return security_ipc_permission(ipcp, flag);
487 * Functions to convert between the kern_ipc_perm structure and the
488 * old/new ipc_perm structures
492 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
493 * @in: kernel permissions
494 * @out: new style IPC permissions
496 * Turn the kernel object 'in' into a set of permissions descriptions
497 * for returning to userspace (out).
501 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
503 out->key = in->key;
504 out->uid = in->uid;
505 out->gid = in->gid;
506 out->cuid = in->cuid;
507 out->cgid = in->cgid;
508 out->mode = in->mode;
509 out->seq = in->seq;
513 * ipc64_perm_to_ipc_perm - convert old ipc permissions to new
514 * @in: new style IPC permissions
515 * @out: old style IPC permissions
517 * Turn the new style permissions object in into a compatibility
518 * object and store it into the 'out' pointer.
521 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
523 out->key = in->key;
524 SET_UID(out->uid, in->uid);
525 SET_GID(out->gid, in->gid);
526 SET_UID(out->cuid, in->cuid);
527 SET_GID(out->cgid, in->cgid);
528 out->mode = in->mode;
529 out->seq = in->seq;
533 * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
534 * is called with shm_ids.mutex locked. Since grow_ary() is also called with
535 * shm_ids.mutex down(for Shared Memory), there is no need to add read
536 * barriers here to gurantee the writes in grow_ary() are seen in order
537 * here (for Alpha).
539 * However ipc_get() itself does not necessary require ipc_ids.mutex down. So
540 * if in the future ipc_get() is used by other places without ipc_ids.mutex
541 * down, then ipc_get() needs read memery barriers as ipc_lock() does.
543 struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id)
545 struct kern_ipc_perm* out;
546 int lid = id % SEQ_MULTIPLIER;
547 if(lid >= ids->entries->size)
548 return NULL;
549 out = ids->entries->p[lid];
550 return out;
553 struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
555 struct kern_ipc_perm* out;
556 int lid = id % SEQ_MULTIPLIER;
557 struct ipc_id_ary* entries;
559 rcu_read_lock();
560 entries = rcu_dereference(ids->entries);
561 if(lid >= entries->size) {
562 rcu_read_unlock();
563 return NULL;
565 out = entries->p[lid];
566 if(out == NULL) {
567 rcu_read_unlock();
568 return NULL;
570 spin_lock(&out->lock);
572 /* ipc_rmid() may have already freed the ID while ipc_lock
573 * was spinning: here verify that the structure is still valid
575 if (out->deleted) {
576 spin_unlock(&out->lock);
577 rcu_read_unlock();
578 return NULL;
580 return out;
583 void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
585 rcu_read_lock();
586 spin_lock(&perm->lock);
589 void ipc_unlock(struct kern_ipc_perm* perm)
591 spin_unlock(&perm->lock);
592 rcu_read_unlock();
595 int ipc_buildid(struct ipc_ids* ids, int id, int seq)
597 return SEQ_MULTIPLIER*seq + id;
600 int ipc_checkid(struct ipc_ids* ids, struct kern_ipc_perm* ipcp, int uid)
602 if(uid/SEQ_MULTIPLIER != ipcp->seq)
603 return 1;
604 return 0;
607 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
611 * ipc_parse_version - IPC call version
612 * @cmd: pointer to command
614 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
615 * The cmd value is turned from an encoding command and version into
616 * just the command code.
619 int ipc_parse_version (int *cmd)
621 if (*cmd & IPC_64) {
622 *cmd ^= IPC_64;
623 return IPC_64;
624 } else {
625 return IPC_OLD;
629 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
631 #ifdef CONFIG_PROC_FS
632 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
634 struct ipc_proc_iface *iface = s->private;
635 struct kern_ipc_perm *ipc = it;
636 loff_t p;
638 /* If we had an ipc id locked before, unlock it */
639 if (ipc && ipc != SEQ_START_TOKEN)
640 ipc_unlock(ipc);
643 * p = *pos - 1 (because id 0 starts at position 1)
644 * + 1 (because we increment the position by one)
646 for (p = *pos; p <= iface->ids->max_id; p++) {
647 if ((ipc = ipc_lock(iface->ids, p)) != NULL) {
648 *pos = p + 1;
649 return ipc;
653 /* Out of range - return NULL to terminate iteration */
654 return NULL;
658 * File positions: pos 0 -> header, pos n -> ipc id + 1.
659 * SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.
661 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
663 struct ipc_proc_iface *iface = s->private;
664 struct kern_ipc_perm *ipc;
665 loff_t p;
668 * Take the lock - this will be released by the corresponding
669 * call to stop().
671 mutex_lock(&iface->ids->mutex);
673 /* pos < 0 is invalid */
674 if (*pos < 0)
675 return NULL;
677 /* pos == 0 means header */
678 if (*pos == 0)
679 return SEQ_START_TOKEN;
681 /* Find the (pos-1)th ipc */
682 for (p = *pos - 1; p <= iface->ids->max_id; p++) {
683 if ((ipc = ipc_lock(iface->ids, p)) != NULL) {
684 *pos = p + 1;
685 return ipc;
688 return NULL;
691 static void sysvipc_proc_stop(struct seq_file *s, void *it)
693 struct kern_ipc_perm *ipc = it;
694 struct ipc_proc_iface *iface = s->private;
696 /* If we had a locked segment, release it */
697 if (ipc && ipc != SEQ_START_TOKEN)
698 ipc_unlock(ipc);
700 /* Release the lock we took in start() */
701 mutex_unlock(&iface->ids->mutex);
704 static int sysvipc_proc_show(struct seq_file *s, void *it)
706 struct ipc_proc_iface *iface = s->private;
708 if (it == SEQ_START_TOKEN)
709 return seq_puts(s, iface->header);
711 return iface->show(s, it);
714 static struct seq_operations sysvipc_proc_seqops = {
715 .start = sysvipc_proc_start,
716 .stop = sysvipc_proc_stop,
717 .next = sysvipc_proc_next,
718 .show = sysvipc_proc_show,
721 static int sysvipc_proc_open(struct inode *inode, struct file *file) {
722 int ret;
723 struct seq_file *seq;
725 ret = seq_open(file, &sysvipc_proc_seqops);
726 if (!ret) {
727 seq = file->private_data;
728 seq->private = PDE(inode)->data;
730 return ret;
733 static struct file_operations sysvipc_proc_fops = {
734 .open = sysvipc_proc_open,
735 .read = seq_read,
736 .llseek = seq_lseek,
737 .release = seq_release,
739 #endif /* CONFIG_PROC_FS */