1/*
2 *  linux/drivers/base/map.c
3 *
4 * (C) Copyright Al Viro 2002,2003
5 *	Released under GPL v2.
6 *
7 * NOTE: data structure needs to be changed.  It works, but for large dev_t
8 * it will be too slow.  It is isolated, though, so these changes will be
9 * local to that file.
10 */
11
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/mutex.h>
15#include <linux/kdev_t.h>
16#include <linux/kobject.h>
17#include <linux/kobj_map.h>
18
19struct kobj_map {
20	struct probe {
21		struct probe *next;
22		dev_t dev;
23		unsigned long range;
24		struct module *owner;
25		kobj_probe_t *get;
26		int (*lock)(dev_t, void *);
27		void *data;
28	} *probes[255];
29	struct mutex *lock;
30};
31
32int kobj_map(struct kobj_map *domain, dev_t dev, unsigned long range,
33	     struct module *module, kobj_probe_t *probe,
34	     int (*lock)(dev_t, void *), void *data)
35{
36	unsigned n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
37	unsigned index = MAJOR(dev);
38	unsigned i;
39	struct probe *p;
40
41	if (n > 255)
42		n = 255;
43
44	p = kmalloc(sizeof(struct probe) * n, GFP_KERNEL);
45
46	if (p == NULL)
47		return -ENOMEM;
48
49	for (i = 0; i < n; i++, p++) {
50		p->owner = module;
51		p->get = probe;
52		p->lock = lock;
53		p->dev = dev;
54		p->range = range;
55		p->data = data;
56	}
57	mutex_lock(domain->lock);
58	for (i = 0, p -= n; i < n; i++, p++, index++) {
59		struct probe **s = &domain->probes[index % 255];
60		while (*s && (*s)->range < range)
61			s = &(*s)->next;
62		p->next = *s;
63		*s = p;
64	}
65	mutex_unlock(domain->lock);
66	return 0;
67}
68
69void kobj_unmap(struct kobj_map *domain, dev_t dev, unsigned long range)
70{
71	unsigned n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
72	unsigned index = MAJOR(dev);
73	unsigned i;
74	struct probe *found = NULL;
75
76	if (n > 255)
77		n = 255;
78
79	mutex_lock(domain->lock);
80	for (i = 0; i < n; i++, index++) {
81		struct probe **s;
82		for (s = &domain->probes[index % 255]; *s; s = &(*s)->next) {
83			struct probe *p = *s;
84			if (p->dev == dev && p->range == range) {
85				*s = p->next;
86				if (!found)
87					found = p;
88				break;
89			}
90		}
91	}
92	mutex_unlock(domain->lock);
93	kfree(found);
94}
95
96struct kobject *kobj_lookup(struct kobj_map *domain, dev_t dev, int *index)
97{
98	struct kobject *kobj;
99	struct probe *p;
100	unsigned long best = ~0UL;
101
102retry:
103	mutex_lock(domain->lock);
104	for (p = domain->probes[MAJOR(dev) % 255]; p; p = p->next) {
105		struct kobject *(*probe)(dev_t, int *, void *);
106		struct module *owner;
107		void *data;
108
109		if (p->dev > dev || p->dev + p->range - 1 < dev)
110			continue;
111		if (p->range - 1 >= best)
112			break;
113		if (!try_module_get(p->owner))
114			continue;
115		owner = p->owner;
116		data = p->data;
117		probe = p->get;
118		best = p->range - 1;
119		*index = dev - p->dev;
120		if (p->lock && p->lock(dev, data) < 0) {
121			module_put(owner);
122			continue;
123		}
124		mutex_unlock(domain->lock);
125		kobj = probe(dev, index, data);
126		/* Currently ->owner protects _only_ ->probe() itself. */
127		module_put(owner);
128		if (kobj)
129			return kobj;
130		goto retry;
131	}
132	mutex_unlock(domain->lock);
133	return NULL;
134}
135
136struct kobj_map *kobj_map_init(kobj_probe_t *base_probe, struct mutex *lock)
137{
138	struct kobj_map *p = kmalloc(sizeof(struct kobj_map), GFP_KERNEL);
139	struct probe *base = kzalloc(sizeof(*base), GFP_KERNEL);
140	int i;
141
142	if ((p == NULL) || (base == NULL)) {
143		kfree(p);
144		kfree(base);
145		return NULL;
146	}
147
148	base->dev = 1;
149	base->range = ~0;
150	base->get = base_probe;
151	for (i = 0; i < 255; i++)
152		p->probes[i] = base;
153	p->lock = lock;
154	return p;
155}
156