int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
{
int start = skb_headlen(skb);
struct sk_buff *frag_iter;
int i, copy;

if (offset > (int)skb->len - len)
goto fault;

/* Copy header. */
if ((copy = start - offset) > 0) {
if (copy > len)
copy = len;
skb_copy_from_linear_data_offset(skb, offset, to, copy);
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}

for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
int end;

WARN_ON(start > offset + len);

end = start + skb_shinfo(skb)->frags[i].size;
if ((copy = end - offset) > 0) {
u8 *vaddr;

if (copy > len)
copy = len;

vaddr = kmap_skb_frag(&skb_shinfo(skb)->frags[i]);
memcpy(to,
vaddr + skb_shinfo(skb)->frags[i].page_offset+
offset - start, copy);
kunmap_skb_frag(vaddr);

if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
start = end;
}

skb_walk_frags(skb, frag_iter) {
int end;

WARN_ON(start > offset + len);

end = start + frag_iter->len;
if ((copy = end - offset) > 0) {
if (copy > len)
copy = len;
if (skb_copy_bits(frag_iter, offset - start, to, copy))
goto fault;
if ((len -= copy) == 0)
return 0;
offset += copy;
to += copy;
}
start = end;
}
if (!len)
return 0;

fault:
return -EFAULT;
}
EXPORT_SYMBOL(skb_copy_bits);

/*
* linux/drivers/base/map.c
*
* (C) Copyright Al Viro 2002,2003
* Released under GPL v2.
*
* NOTE: data structure needs to be changed. It works, but for large dev_t
* it will be too slow. It is isolated, though, so these changes will be
* local to that file.
*/

#include
#include
#include
#include
#include
#include

struct kobj_map {
struct probe {
struct probe *next;
dev_t dev;
unsigned long range;
struct module *owner;
kobj_probe_t *get;
int (*lock)(dev_t, void *);
void *data;
} *probes[255];
struct mutex *lock;
};

int kobj_map(struct kobj_map *domain, dev_t dev, unsigned long range,
struct module *module, kobj_probe_t *probe,
int (*lock)(dev_t, void *), void *data)
{
unsigned n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
unsigned index = MAJOR(dev);
unsigned i;
struct probe *p;

if (n > 255)
n = 255;

p = kmalloc(sizeof(struct probe) * n, GFP_KERNEL);

if (p == NULL)
return -ENOMEM;

for (i = 0; i < n; i++, p++) {
p->owner = module;
p->get = probe;
p->lock = lock;
p->dev = dev;
p->range = range;
p->data = data;
}
mutex_lock(domain->lock);
for (i = 0, p -= n; i < n; i++, p++, index++) {
struct probe **s = &domain->probes[index % 255];
while (*s && (*s)->range < range)
s = &(*s)->next;
p->next = *s;
*s = p;
}
mutex_unlock(domain->lock);
return 0;
}

void kobj_unmap(struct kobj_map *domain, dev_t dev, unsigned long range)
{
unsigned n = MAJOR(dev + range - 1) - MAJOR(dev) + 1;
unsigned index = MAJOR(dev);
unsigned i;
struct probe *found = NULL;

if (n > 255)
n = 255;

mutex_lock(domain->lock);
for (i = 0; i < n; i++, index++) {
struct probe **s;
for (s = &domain->probes[index % 255]; *s; s = &(*s)->next) {
struct probe *p = *s;
if (p->dev == dev && p->range == range) {
*s = p->next;
if (!found)
found = p;
break;
}
}
}
mutex_unlock(domain->lock);
kfree(found);
}