You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
408 lines
9.4 KiB
408 lines
9.4 KiB
/*
|
|
* 2002-10-18 written by Jim Houston jim.houston@ccur.com
|
|
* Copyright (C) 2002 by Concurrent Computer Corporation
|
|
* Distributed under the GNU GPL license version 2.
|
|
*
|
|
* Modified by George Anzinger to reuse immediately and to use
|
|
* find bit instructions. Also removed _irq on spinlocks.
|
|
*
|
|
* Small id to pointer translation service.
|
|
*
|
|
* It uses a radix tree like structure as a sparse array indexed
|
|
* by the id to obtain the pointer. The bitmap makes allocating
|
|
* a new id quick.
|
|
*
|
|
* You call it to allocate an id (an int) an associate with that id a
|
|
* pointer or what ever, we treat it as a (void *). You can pass this
|
|
* id to a user for him to pass back at a later time. You then pass
|
|
* that id to this code and it returns your pointer.
|
|
|
|
* You can release ids at any time. When all ids are released, most of
|
|
* the memory is returned (we keep IDR_FREE_MAX) in a local pool so we
|
|
* don't need to go to the memory "store" during an id allocate, just
|
|
* so you don't need to be too concerned about locking and conflicts
|
|
* with the slab allocator.
|
|
*/
|
|
|
|
#ifndef TEST // to test in user space...
|
|
#include <linux/slab.h>
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#endif
|
|
#include <linux/string.h>
|
|
#include <linux/idr.h>
|
|
|
|
static kmem_cache_t *idr_layer_cache;
|
|
|
|
static struct idr_layer *alloc_layer(struct idr *idp)
|
|
{
|
|
struct idr_layer *p;
|
|
|
|
spin_lock(&idp->lock);
|
|
if ((p = idp->id_free)) {
|
|
idp->id_free = p->ary[0];
|
|
idp->id_free_cnt--;
|
|
p->ary[0] = NULL;
|
|
}
|
|
spin_unlock(&idp->lock);
|
|
return(p);
|
|
}
|
|
|
|
static void free_layer(struct idr *idp, struct idr_layer *p)
|
|
{
|
|
/*
|
|
* Depends on the return element being zeroed.
|
|
*/
|
|
spin_lock(&idp->lock);
|
|
p->ary[0] = idp->id_free;
|
|
idp->id_free = p;
|
|
idp->id_free_cnt++;
|
|
spin_unlock(&idp->lock);
|
|
}
|
|
|
|
/**
|
|
* idr_pre_get - reserver resources for idr allocation
|
|
* @idp: idr handle
|
|
* @gfp_mask: memory allocation flags
|
|
*
|
|
* This function should be called prior to locking and calling the
|
|
* following function. It preallocates enough memory to satisfy
|
|
* the worst possible allocation.
|
|
*
|
|
* If the system is REALLY out of memory this function returns 0,
|
|
* otherwise 1.
|
|
*/
|
|
int idr_pre_get(struct idr *idp, unsigned gfp_mask)
|
|
{
|
|
while (idp->id_free_cnt < IDR_FREE_MAX) {
|
|
struct idr_layer *new;
|
|
new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
|
|
if(new == NULL)
|
|
return (0);
|
|
free_layer(idp, new);
|
|
}
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(idr_pre_get);
|
|
|
|
static int sub_alloc(struct idr *idp, void *ptr, int *starting_id)
|
|
{
|
|
int n, m, sh;
|
|
struct idr_layer *p, *new;
|
|
struct idr_layer *pa[MAX_LEVEL];
|
|
int l, id;
|
|
long bm;
|
|
|
|
id = *starting_id;
|
|
p = idp->top;
|
|
l = idp->layers;
|
|
pa[l--] = NULL;
|
|
while (1) {
|
|
/*
|
|
* We run around this while until we reach the leaf node...
|
|
*/
|
|
n = (id >> (IDR_BITS*l)) & IDR_MASK;
|
|
bm = ~p->bitmap;
|
|
m = find_next_bit(&bm, IDR_SIZE, n);
|
|
if (m == IDR_SIZE) {
|
|
/* no space available go back to previous layer. */
|
|
l++;
|
|
id = (id | ((1 << (IDR_BITS*l))-1)) + 1;
|
|
if (!(p = pa[l])) {
|
|
*starting_id = id;
|
|
return -2;
|
|
}
|
|
continue;
|
|
}
|
|
if (m != n) {
|
|
sh = IDR_BITS*l;
|
|
id = ((id >> sh) ^ n ^ m) << sh;
|
|
}
|
|
if ((id >= MAX_ID_BIT) || (id < 0))
|
|
return -3;
|
|
if (l == 0)
|
|
break;
|
|
/*
|
|
* Create the layer below if it is missing.
|
|
*/
|
|
if (!p->ary[m]) {
|
|
if (!(new = alloc_layer(idp)))
|
|
return -1;
|
|
p->ary[m] = new;
|
|
p->count++;
|
|
}
|
|
pa[l--] = p;
|
|
p = p->ary[m];
|
|
}
|
|
/*
|
|
* We have reached the leaf node, plant the
|
|
* users pointer and return the raw id.
|
|
*/
|
|
p->ary[m] = (struct idr_layer *)ptr;
|
|
__set_bit(m, &p->bitmap);
|
|
p->count++;
|
|
/*
|
|
* If this layer is full mark the bit in the layer above
|
|
* to show that this part of the radix tree is full.
|
|
* This may complete the layer above and require walking
|
|
* up the radix tree.
|
|
*/
|
|
n = id;
|
|
while (p->bitmap == IDR_FULL) {
|
|
if (!(p = pa[++l]))
|
|
break;
|
|
n = n >> IDR_BITS;
|
|
__set_bit((n & IDR_MASK), &p->bitmap);
|
|
}
|
|
return(id);
|
|
}
|
|
|
|
static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
|
|
{
|
|
struct idr_layer *p, *new;
|
|
int layers, v, id;
|
|
|
|
id = starting_id;
|
|
build_up:
|
|
p = idp->top;
|
|
layers = idp->layers;
|
|
if (unlikely(!p)) {
|
|
if (!(p = alloc_layer(idp)))
|
|
return -1;
|
|
layers = 1;
|
|
}
|
|
/*
|
|
* Add a new layer to the top of the tree if the requested
|
|
* id is larger than the currently allocated space.
|
|
*/
|
|
while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
|
|
layers++;
|
|
if (!p->count)
|
|
continue;
|
|
if (!(new = alloc_layer(idp))) {
|
|
/*
|
|
* The allocation failed. If we built part of
|
|
* the structure tear it down.
|
|
*/
|
|
for (new = p; p && p != idp->top; new = p) {
|
|
p = p->ary[0];
|
|
new->ary[0] = NULL;
|
|
new->bitmap = new->count = 0;
|
|
free_layer(idp, new);
|
|
}
|
|
return -1;
|
|
}
|
|
new->ary[0] = p;
|
|
new->count = 1;
|
|
if (p->bitmap == IDR_FULL)
|
|
__set_bit(0, &new->bitmap);
|
|
p = new;
|
|
}
|
|
idp->top = p;
|
|
idp->layers = layers;
|
|
v = sub_alloc(idp, ptr, &id);
|
|
if (v == -2)
|
|
goto build_up;
|
|
return(v);
|
|
}
|
|
|
|
/**
|
|
* idr_get_new_above - allocate new idr entry above or equal to a start id
|
|
* @idp: idr handle
|
|
* @ptr: pointer you want associated with the ide
|
|
* @start_id: id to start search at
|
|
* @id: pointer to the allocated handle
|
|
*
|
|
* This is the allocate id function. It should be called with any
|
|
* required locks.
|
|
*
|
|
* If memory is required, it will return -EAGAIN, you should unlock
|
|
* and go back to the idr_pre_get() call. If the idr is full, it will
|
|
* return -ENOSPC.
|
|
*
|
|
* @id returns a value in the range 0 ... 0x7fffffff
|
|
*/
|
|
int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
|
|
{
|
|
int rv;
|
|
rv = idr_get_new_above_int(idp, ptr, starting_id);
|
|
/*
|
|
* This is a cheap hack until the IDR code can be fixed to
|
|
* return proper error values.
|
|
*/
|
|
if (rv < 0) {
|
|
if (rv == -1)
|
|
return -EAGAIN;
|
|
else /* Will be -3 */
|
|
return -ENOSPC;
|
|
}
|
|
*id = rv;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(idr_get_new_above);
|
|
|
|
/**
|
|
* idr_get_new - allocate new idr entry
|
|
* @idp: idr handle
|
|
* @ptr: pointer you want associated with the ide
|
|
* @id: pointer to the allocated handle
|
|
*
|
|
* This is the allocate id function. It should be called with any
|
|
* required locks.
|
|
*
|
|
* If memory is required, it will return -EAGAIN, you should unlock
|
|
* and go back to the idr_pre_get() call. If the idr is full, it will
|
|
* return -ENOSPC.
|
|
*
|
|
* @id returns a value in the range 0 ... 0x7fffffff
|
|
*/
|
|
int idr_get_new(struct idr *idp, void *ptr, int *id)
|
|
{
|
|
int rv;
|
|
rv = idr_get_new_above_int(idp, ptr, 0);
|
|
/*
|
|
* This is a cheap hack until the IDR code can be fixed to
|
|
* return proper error values.
|
|
*/
|
|
if (rv < 0) {
|
|
if (rv == -1)
|
|
return -EAGAIN;
|
|
else /* Will be -3 */
|
|
return -ENOSPC;
|
|
}
|
|
*id = rv;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(idr_get_new);
|
|
|
|
static void idr_remove_warning(int id)
|
|
{
|
|
printk("idr_remove called for id=%d which is not allocated.\n", id);
|
|
dump_stack();
|
|
}
|
|
|
|
static void sub_remove(struct idr *idp, int shift, int id)
|
|
{
|
|
struct idr_layer *p = idp->top;
|
|
struct idr_layer **pa[MAX_LEVEL];
|
|
struct idr_layer ***paa = &pa[0];
|
|
int n;
|
|
|
|
*paa = NULL;
|
|
*++paa = &idp->top;
|
|
|
|
while ((shift > 0) && p) {
|
|
n = (id >> shift) & IDR_MASK;
|
|
__clear_bit(n, &p->bitmap);
|
|
*++paa = &p->ary[n];
|
|
p = p->ary[n];
|
|
shift -= IDR_BITS;
|
|
}
|
|
n = id & IDR_MASK;
|
|
if (likely(p != NULL && test_bit(n, &p->bitmap))){
|
|
__clear_bit(n, &p->bitmap);
|
|
p->ary[n] = NULL;
|
|
while(*paa && ! --((**paa)->count)){
|
|
free_layer(idp, **paa);
|
|
**paa-- = NULL;
|
|
}
|
|
if ( ! *paa )
|
|
idp->layers = 0;
|
|
} else {
|
|
idr_remove_warning(id);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* idr_remove - remove the given id and free it's slot
|
|
* idp: idr handle
|
|
* id: uniqueue key
|
|
*/
|
|
void idr_remove(struct idr *idp, int id)
|
|
{
|
|
struct idr_layer *p;
|
|
|
|
/* Mask off upper bits we don't use for the search. */
|
|
id &= MAX_ID_MASK;
|
|
|
|
sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
|
|
if ( idp->top && idp->top->count == 1 &&
|
|
(idp->layers > 1) &&
|
|
idp->top->ary[0]){ // We can drop a layer
|
|
|
|
p = idp->top->ary[0];
|
|
idp->top->bitmap = idp->top->count = 0;
|
|
free_layer(idp, idp->top);
|
|
idp->top = p;
|
|
--idp->layers;
|
|
}
|
|
while (idp->id_free_cnt >= IDR_FREE_MAX) {
|
|
|
|
p = alloc_layer(idp);
|
|
kmem_cache_free(idr_layer_cache, p);
|
|
return;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(idr_remove);
|
|
|
|
/**
|
|
* idr_find - return pointer for given id
|
|
* @idp: idr handle
|
|
* @id: lookup key
|
|
*
|
|
* Return the pointer given the id it has been registered with. A %NULL
|
|
* return indicates that @id is not valid or you passed %NULL in
|
|
* idr_get_new().
|
|
*
|
|
* The caller must serialize idr_find() vs idr_get_new() and idr_remove().
|
|
*/
|
|
void *idr_find(struct idr *idp, int id)
|
|
{
|
|
int n;
|
|
struct idr_layer *p;
|
|
|
|
n = idp->layers * IDR_BITS;
|
|
p = idp->top;
|
|
|
|
/* Mask off upper bits we don't use for the search. */
|
|
id &= MAX_ID_MASK;
|
|
|
|
if (id >= (1 << n))
|
|
return NULL;
|
|
|
|
while (n > 0 && p) {
|
|
n -= IDR_BITS;
|
|
p = p->ary[(id >> n) & IDR_MASK];
|
|
}
|
|
return((void *)p);
|
|
}
|
|
EXPORT_SYMBOL(idr_find);
|
|
|
|
static void idr_cache_ctor(void * idr_layer,
|
|
kmem_cache_t *idr_layer_cache, unsigned long flags)
|
|
{
|
|
memset(idr_layer, 0, sizeof(struct idr_layer));
|
|
}
|
|
|
|
static int init_id_cache(void)
|
|
{
|
|
if (!idr_layer_cache)
|
|
idr_layer_cache = kmem_cache_create("idr_layer_cache",
|
|
sizeof(struct idr_layer), 0, 0, idr_cache_ctor, NULL);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* idr_init - initialize idr handle
|
|
* @idp: idr handle
|
|
*
|
|
* This function is use to set up the handle (@idp) that you will pass
|
|
* to the rest of the functions.
|
|
*/
|
|
void idr_init(struct idr *idp)
|
|
{
|
|
init_id_cache();
|
|
memset(idp, 0, sizeof(struct idr));
|
|
spin_lock_init(&idp->lock);
|
|
}
|
|
EXPORT_SYMBOL(idr_init);
|
|
|