LXR linux/drivers/base/map.c

   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