LXR linux/drivers/base/map.c

   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