1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  linux/drivers/base/map.c
4 *
5 * (C) Copyright Al Viro 2002,2003
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 int n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
37	unsigned int index = MAJOR(dev);
38	unsigned int i;
39	struct probe *p;
40
41	if (n > 255)
42		n = 255;
43
44	p = kmalloc_array(n, sizeof(struct probe), GFP_KERNEL);
45	if (p == NULL)
46		return -ENOMEM;
47
48	for (i = 0; i < n; i++, p++) {
49		p->owner = module;
50		p->get = probe;
51		p->lock = lock;
52		p->dev = dev;
53		p->range = range;
54		p->data = data;
55	}
56	mutex_lock(domain->lock);
57	for (i = 0, p -= n; i < n; i++, p++, index++) {
58		struct probe **s = &domain->probes[index % 255];
59		while (*s && (*s)->range < range)
60			s = &(*s)->next;
61		p->next = *s;
62		*s = p;
63	}
64	mutex_unlock(domain->lock);
65	return 0;
66}
67
68void kobj_unmap(struct kobj_map *domain, dev_t dev, unsigned long range)
69{
70	unsigned int n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
71	unsigned int index = MAJOR(dev);
72	unsigned int i;
73	struct probe *found = NULL;
74
75	if (n > 255)
76		n = 255;
77
78	mutex_lock(domain->lock);
79	for (i = 0; i < n; i++, index++) {
80		struct probe **s;
81		for (s = &domain->probes[index % 255]; *s; s = &(*s)->next) {
82			struct probe *p = *s;
83			if (p->dev == dev && p->range == range) {
84				*s = p->next;
85				if (!found)
86					found = p;
87				break;
88			}
89		}
90	}
91	mutex_unlock(domain->lock);
92	kfree(found);
93}
94
95struct kobject *kobj_lookup(struct kobj_map *domain, dev_t dev, int *index)
96{
97	struct kobject *kobj;
98	struct probe *p;
99	unsigned long best = ~0UL;
100
101retry:
102	mutex_lock(domain->lock);
103	for (p = domain->probes[MAJOR(dev) % 255]; p; p = p->next) {
104		struct kobject *(*probe)(dev_t, int *, void *);
105		struct module *owner;
106		void *data;
107
108		if (p->dev > dev || p->dev + p->range - 1 < dev)
109			continue;
110		if (p->range - 1 >= best)
111			break;
112		if (!try_module_get(p->owner))
113			continue;
114		owner = p->owner;
115		data = p->data;
116		probe = p->get;
117		best = p->range - 1;
118		*index = dev - p->dev;
119		if (p->lock && p->lock(dev, data) < 0) {
120			module_put(owner);
121			continue;
122		}
123		mutex_unlock(domain->lock);
124		kobj = probe(dev, index, data);
125		/* Currently ->owner protects _only_ ->probe() itself. */
126		module_put(owner);
127		if (kobj)
128			return kobj;
129		goto retry;
130	}
131	mutex_unlock(domain->lock);
132	return NULL;
133}
134
135struct kobj_map *kobj_map_init(kobj_probe_t *base_probe, struct mutex *lock)
136{
137	struct kobj_map *p = kmalloc(sizeof(struct kobj_map), GFP_KERNEL);
138	struct probe *base = kzalloc(sizeof(*base), GFP_KERNEL);
139	int i;
140
141	if ((p == NULL) || (base == NULL)) {
142		kfree(p);
143		kfree(base);
144		return NULL;
145	}
146
147	base->dev = 1;
148	base->range = ~0;
149	base->get = base_probe;
150	for (i = 0; i < 255; i++)
151		p->probes[i] = base;
152	p->lock = lock;
153	return p;
154}
155