/* * 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, gfp_t 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_destroy - release all cached layers within an idr tree * idp: idr handle */void idr_destroy(struct idr *idp){	while (idp->id_free_cnt) {		struct idr_layer *p = alloc_layer(idp);		kmem_cache_free(idr_layer_cache, p);	}}EXPORT_SYMBOL(idr_destroy); /** * 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);