WebSVN – Kolibri OS – Diff – /drivers/ddk/linux/idr.c


/*
 * 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.
 *
 * Modified by Nadia Derbey to make it RCU safe.
 *
 * 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 MAX_IDR_FREE) 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.
 */
 
#include 
#include 
#include 
#include 
#include 
//#include 
 
static inline void * __must_check ERR_PTR(long error)
{
	return (void *) error;
}
 
unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
                                 unsigned long offset);
 
 
#define MAX_IDR_SHIFT		(sizeof(int) * 8 - 1)
#define MAX_IDR_BIT		(1U << MAX_IDR_SHIFT)
 
/* Leave the possibility of an incomplete final layer */
#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
 
/* Number of id_layer structs to leave in free list */
#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
 
static struct idr_layer *idr_preload_head;
static int idr_preload_cnt;
 
static DEFINE_SPINLOCK(simple_ida_lock);
 
/* the maximum ID which can be allocated given idr->layers */
static int idr_max(int layers)
{
	int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
 
	return (1 << bits) - 1;
}
 
/*
 * Prefix mask for an idr_layer at @layer.  For layer 0, the prefix mask is
 * all bits except for the lower IDR_BITS.  For layer 1, 2 * IDR_BITS, and
 * so on.
 */
static int idr_layer_prefix_mask(int layer)
{
	return ~idr_max(layer + 1);
}
 
static struct idr_layer *get_from_free_list(struct idr *idp)
{
	struct idr_layer *p;
	unsigned long flags;
 
	spin_lock_irqsave(&idp->lock, flags);
	if ((p = idp->id_free)) {
		idp->id_free = p->ary[0];
		idp->id_free_cnt--;
		p->ary[0] = NULL;
	}
	spin_unlock_irqrestore(&idp->lock, flags);
	return(p);
}
 
/**
 * idr_layer_alloc - allocate a new idr_layer
 * @gfp_mask: allocation mask
 * @layer_idr: optional idr to allocate from
 *
 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
 * one from the per-cpu preload buffer.  If @layer_idr is not %NULL, fetch
 * an idr_layer from @idr->id_free.
 *
 * @layer_idr is to maintain backward compatibility with the old alloc
 * interface - idr_pre_get() and idr_get_new*() - and will be removed
 * together with per-pool preload buffer.
 */
static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
{
	struct idr_layer *new;
 
	/* this is the old path, bypass to get_from_free_list() */
	if (layer_idr)
		return get_from_free_list(layer_idr);
 
	/* try to allocate directly from kmem_cache */
	new = kzalloc(sizeof(struct idr_layer), gfp_mask);
	if (new)
		return new;
 
 
	new = idr_preload_head;
	if (new) {
		idr_preload_head = new->ary[0];
		idr_preload_cnt--;
		new->ary[0] = NULL;
	}
	preempt_enable();
	return new;
}
 
static void idr_layer_rcu_free(struct rcu_head *head)
{
	struct idr_layer *layer;
 
    layer = container_of(head, struct idr_layer, rcu_head);
    kfree(layer);
}
 
static inline void free_layer(struct idr *idr, struct idr_layer *p)
{
	if (idr->hint && idr->hint == p)
		RCU_INIT_POINTER(idr->hint, NULL);
    idr_layer_rcu_free(&p->rcu_head);
}
 
/* only called when idp->lock is held */
static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
{
	p->ary[0] = idp->id_free;
	idp->id_free = p;
	idp->id_free_cnt++;
}
 
static void move_to_free_list(struct idr *idp, struct idr_layer *p)
{
	unsigned long flags;
 
	/*
	 * Depends on the return element being zeroed.
	 */
	spin_lock_irqsave(&idp->lock, flags);
	__move_to_free_list(idp, p);
	spin_unlock_irqrestore(&idp->lock, flags);
}
 
static void idr_mark_full(struct idr_layer **pa, int id)
{
	struct idr_layer *p = pa[0];
	int l = 0;
 
	__set_bit(id & IDR_MASK, p->bitmap);
	/*
	 * 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.
	 */
	while (bitmap_full(p->bitmap, IDR_SIZE)) {
		if (!(p = pa[++l]))
			break;
		id = id >> IDR_BITS;
		__set_bit((id & IDR_MASK), p->bitmap);
	}
}
 
int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
{
	while (idp->id_free_cnt < MAX_IDR_FREE) {
       struct idr_layer *new;
       new = kzalloc(sizeof(struct idr_layer), gfp_mask);
       if (new == NULL)
           return (0);
       move_to_free_list(idp, new);
   }
   return 1;
}
EXPORT_SYMBOL(__idr_pre_get);
 
/**
 * sub_alloc - try to allocate an id without growing the tree depth
 * @idp: idr handle
 * @starting_id: id to start search at
 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
 * @gfp_mask: allocation mask for idr_layer_alloc()
 * @layer_idr: optional idr passed to idr_layer_alloc()
 *
 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
 * growing its depth.  Returns
 *
 *  the allocated id >= 0 if successful,
 *  -EAGAIN if the tree needs to grow for allocation to succeed,
 *  -ENOSPC if the id space is exhausted,
 *  -ENOMEM if more idr_layers need to be allocated.
 */
static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
		     gfp_t gfp_mask, struct idr *layer_idr)
{
	int n, m, sh;
	struct idr_layer *p, *new;
	int l, id, oid;
 
	id = *starting_id;
 restart:
	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;
		m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
		if (m == IDR_SIZE) {
			/* no space available go back to previous layer. */
			l++;
			oid = id;
			id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
 
			/* if already at the top layer, we need to grow */
			if (id >= 1 << (idp->layers * IDR_BITS)) {
				*starting_id = id;
				return -EAGAIN;
			}
			p = pa[l];
			BUG_ON(!p);
 
			/* If we need to go up one layer, continue the
			 * loop; otherwise, restart from the top.
			 */
			sh = IDR_BITS * (l + 1);
			if (oid >> sh == id >> sh)
				continue;
			else
				goto restart;
		}
		if (m != n) {
			sh = IDR_BITS*l;
			id = ((id >> sh) ^ n ^ m) << sh;
		}
		if ((id >= MAX_IDR_BIT) || (id < 0))
			return -ENOSPC;
		if (l == 0)
			break;
		/*
		 * Create the layer below if it is missing.
		 */
		if (!p->ary[m]) {
			new = idr_layer_alloc(gfp_mask, layer_idr);
			if (!new)
				return -ENOMEM;
			new->layer = l-1;
			new->prefix = id & idr_layer_prefix_mask(new->layer);
			rcu_assign_pointer(p->ary[m], new);
			p->count++;
		}
		pa[l--] = p;
		p = p->ary[m];
	}
 
	pa[l] = p;
	return id;
}
 
static int idr_get_empty_slot(struct idr *idp, int starting_id,
			      struct idr_layer **pa, gfp_t gfp_mask,
			      struct idr *layer_idr)
{
	struct idr_layer *p, *new;
	int layers, v, id;
	unsigned long flags;
 
	id = starting_id;
build_up:
	p = idp->top;
	layers = idp->layers;
	if (unlikely(!p)) {
		if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
			return -ENOMEM;
		p->layer = 0;
		layers = 1;
	}
	/*
	 * Add a new layer to the top of the tree if the requested
	 * id is larger than the currently allocated space.
	 */
	while (id > idr_max(layers)) {
		layers++;
		if (!p->count) {
			/* special case: if the tree is currently empty,
			 * then we grow the tree by moving the top node
			 * upwards.
			 */
			p->layer++;
			WARN_ON_ONCE(p->prefix);
			continue;
		}
		if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
			/*
			 * The allocation failed.  If we built part of
			 * the structure tear it down.
			 */
			spin_lock_irqsave(&idp->lock, flags);
			for (new = p; p && p != idp->top; new = p) {
				p = p->ary[0];
				new->ary[0] = NULL;
				new->count = 0;
				bitmap_clear(new->bitmap, 0, IDR_SIZE);
				__move_to_free_list(idp, new);
			}
			spin_unlock_irqrestore(&idp->lock, flags);
			return -ENOMEM;
		}
		new->ary[0] = p;
		new->count = 1;
		new->layer = layers-1;
		new->prefix = id & idr_layer_prefix_mask(new->layer);
		if (bitmap_full(p->bitmap, IDR_SIZE))
			__set_bit(0, new->bitmap);
		p = new;
	}
	rcu_assign_pointer(idp->top, p);
	idp->layers = layers;
	v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
	if (v == -EAGAIN)
		goto build_up;
	return(v);
}
 
/*
 * @id and @pa are from a successful allocation from idr_get_empty_slot().
 * Install the user pointer @ptr and mark the slot full.
 */
static void idr_fill_slot(struct idr *idr, void *ptr, int id,
			  struct idr_layer **pa)
{
	/* update hint used for lookup, cleared from free_layer() */
	rcu_assign_pointer(idr->hint, pa[0]);
 
	rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
		pa[0]->count++;
		idr_mark_full(pa, id);
}
 
int __idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
{
	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
	int rv;
 
	rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp);
	if (rv < 0)
		return rv == -ENOMEM ? -EAGAIN : rv;
 
	idr_fill_slot(idp, ptr, rv, pa);
	*id = rv;
    return 0;
}
EXPORT_SYMBOL(__idr_get_new_above);
 
/**
 * idr_preload - preload for idr_alloc()
 * @gfp_mask: allocation mask to use for preloading
 *
 * Preload per-cpu layer buffer for idr_alloc().  Can only be used from
 * process context and each idr_preload() invocation should be matched with
 * idr_preload_end().  Note that preemption is disabled while preloaded.
 *
 * The first idr_alloc() in the preloaded section can be treated as if it
 * were invoked with @gfp_mask used for preloading.  This allows using more
 * permissive allocation masks for idrs protected by spinlocks.
 *
 * For example, if idr_alloc() below fails, the failure can be treated as
 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
 *
 *	idr_preload(GFP_KERNEL);
 *	spin_lock(lock);
 *
 *	id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
 *
 *	spin_unlock(lock);
 *	idr_preload_end();
 *	if (id < 0)
 *		error;
 */
void idr_preload(gfp_t gfp_mask)
{
 
	/*
	 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
	 * return value from idr_alloc() needs to be checked for failure
	 * anyway.  Silently give up if allocation fails.  The caller can
	 * treat failures from idr_alloc() as if idr_alloc() were called
	 * with @gfp_mask which should be enough.
	 */
	while (idr_preload_cnt < MAX_IDR_FREE) {
		struct idr_layer *new;
 
		new = kzalloc(sizeof(struct idr_layer), gfp_mask);
		if (!new)
			break;
 
		/* link the new one to per-cpu preload list */
		new->ary[0] = idr_preload_head;
		idr_preload_head = new;
		idr_preload_cnt++;
	}
}
EXPORT_SYMBOL(idr_preload);
 
/**
 * idr_alloc - allocate new idr entry
 * @idr: the (initialized) idr
 * @ptr: pointer to be associated with the new id
 * @start: the minimum id (inclusive)
 * @end: the maximum id (exclusive, <= 0 for max)
 * @gfp_mask: memory allocation flags
 *
 * Allocate an id in [start, end) and associate it with @ptr.  If no ID is
 * available in the specified range, returns -ENOSPC.  On memory allocation
 * failure, returns -ENOMEM.
 *
 * Note that @end is treated as max when <= 0.  This is to always allow
 * using @start + N as @end as long as N is inside integer range.
 *
 * The user is responsible for exclusively synchronizing all operations
 * which may modify @idr.  However, read-only accesses such as idr_find()
 * or iteration can be performed under RCU read lock provided the user
 * destroys @ptr in RCU-safe way after removal from idr.
 */
int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
{
	int max = end > 0 ? end - 1 : INT_MAX;	/* inclusive upper limit */
	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
	int id;
 
	/* sanity checks */
	if (WARN_ON_ONCE(start < 0))
		return -EINVAL;
	if (unlikely(max < start))
		return -ENOSPC;
 
	/* allocate id */
	id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
	if (unlikely(id < 0))
		return id;
	if (unlikely(id > max))
		return -ENOSPC;
 
	idr_fill_slot(idr, ptr, id, pa);
	return id;
}
EXPORT_SYMBOL_GPL(idr_alloc);
 
/**
 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
 * @idr: the (initialized) idr
 * @ptr: pointer to be associated with the new id
 * @start: the minimum id (inclusive)
 * @end: the maximum id (exclusive, <= 0 for max)
 * @gfp_mask: memory allocation flags
 *
 * Essentially the same as idr_alloc, but prefers to allocate progressively
 * higher ids if it can. If the "cur" counter wraps, then it will start again
 * at the "start" end of the range and allocate one that has already been used.
 */
int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
			gfp_t gfp_mask)
{
	int id;
 
	id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
	if (id == -ENOSPC)
		id = idr_alloc(idr, ptr, start, end, gfp_mask);
 
	if (likely(id >= 0))
		idr->cur = id + 1;
	return id;
}
EXPORT_SYMBOL(idr_alloc_cyclic);
 
static void idr_remove_warning(int id)
{
	WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
}
 
static void sub_remove(struct idr *idp, int shift, int id)
{
	struct idr_layer *p = idp->top;
	struct idr_layer **pa[MAX_IDR_LEVEL + 1];
	struct idr_layer ***paa = &pa[0];
	struct idr_layer *to_free;
	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);
		rcu_assign_pointer(p->ary[n], NULL);
		to_free = NULL;
		while(*paa && ! --((**paa)->count)){
			if (to_free)
				free_layer(idp, to_free);
			to_free = **paa;
			**paa-- = NULL;
		}
		if (!*paa)
			idp->layers = 0;
		if (to_free)
			free_layer(idp, to_free);
	} else
		idr_remove_warning(id);
}
 
/**
 * idr_remove - remove the given id and free its slot
 * @idp: idr handle
 * @id: unique key
 */
void idr_remove(struct idr *idp, int id)
{
	struct idr_layer *p;
	struct idr_layer *to_free;
 
	if (id < 0)
		return;
 
	sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
	if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
	    idp->top->ary[0]) {
		/*
		 * Single child at leftmost slot: we can shrink the tree.
		 * This level is not needed anymore since when layers are
		 * inserted, they are inserted at the top of the existing
		 * tree.
		 */
		to_free = idp->top;
		p = idp->top->ary[0];
		rcu_assign_pointer(idp->top, p);
		--idp->layers;
		to_free->count = 0;
		bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
		free_layer(idp, to_free);
	}
	while (idp->id_free_cnt >= MAX_IDR_FREE) {
		p = get_from_free_list(idp);
		/*
		 * Note: we don't call the rcu callback here, since the only
		 * layers that fall into the freelist are those that have been
		 * preallocated.
		 */
        kfree(p);
	}
	return;
}
EXPORT_SYMBOL(idr_remove);
 
void __idr_remove_all(struct idr *idp)
{
	int n, id, max;
	int bt_mask;
	struct idr_layer *p;
	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
	struct idr_layer **paa = &pa[0];
 
	n = idp->layers * IDR_BITS;
	p = idp->top;
	rcu_assign_pointer(idp->top, NULL);
	max = idr_max(idp->layers);
 
	id = 0;
	while (id >= 0 && id <= max) {
		while (n > IDR_BITS && p) {
			n -= IDR_BITS;
			*paa++ = p;
			p = p->ary[(id >> n) & IDR_MASK];
		}
 
		bt_mask = id;
		id += 1 << n;
		/* Get the highest bit that the above add changed from 0->1. */
		while (n < fls(id ^ bt_mask)) {
			if (p)
				free_layer(idp, p);
			n += IDR_BITS;
			p = *--paa;
		}
	}
	idp->layers = 0;
}
EXPORT_SYMBOL(__idr_remove_all);
 
/**
 * idr_destroy - release all cached layers within an idr tree
 * @idp: idr handle
 *
 * Free all id mappings and all idp_layers.  After this function, @idp is
 * completely unused and can be freed / recycled.  The caller is
 * responsible for ensuring that no one else accesses @idp during or after
 * idr_destroy().
 *
 * A typical clean-up sequence for objects stored in an idr tree will use
 * idr_for_each() to free all objects, if necessay, then idr_destroy() to
 * free up the id mappings and cached idr_layers.
 */
void idr_destroy(struct idr *idp)
{
	__idr_remove_all(idp);
 
	while (idp->id_free_cnt) {
		struct idr_layer *p = get_from_free_list(idp);
        kfree(p);
	}
}
EXPORT_SYMBOL(idr_destroy);
 
void *idr_find_slowpath(struct idr *idp, int id)
{
	int n;
	struct idr_layer *p;
 
	if (id < 0)
		return NULL;
 
	p = rcu_dereference_raw(idp->top);
	if (!p)
		return NULL;
	n = (p->layer+1) * IDR_BITS;
 
	if (id > idr_max(p->layer + 1))
		return NULL;
	BUG_ON(n == 0);
 
	while (n > 0 && p) {
		n -= IDR_BITS;
		BUG_ON(n != p->layer*IDR_BITS);
		p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
	}
	return((void *)p);
}
EXPORT_SYMBOL(idr_find_slowpath);
 
 
/**
 * idr_for_each - iterate through all stored pointers
 * @idp: idr handle
 * @fn: function to be called for each pointer
 * @data: data passed back to callback function
 *
 * Iterate over the pointers registered with the given idr.  The
 * callback function will be called for each pointer currently
 * registered, passing the id, the pointer and the data pointer passed
 * to this function.  It is not safe to modify the idr tree while in
 * the callback, so functions such as idr_get_new and idr_remove are
 * not allowed.
 *
 * We check the return of @fn each time. If it returns anything other
 * than %0, we break out and return that value.
 *
 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
 */
int idr_for_each(struct idr *idp,
		 int (*fn)(int id, void *p, void *data), void *data)
{
	int n, id, max, error = 0;
	struct idr_layer *p;
	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
	struct idr_layer **paa = &pa[0];
 
	n = idp->layers * IDR_BITS;
	p = rcu_dereference_raw(idp->top);
	max = idr_max(idp->layers);
 
	id = 0;
	while (id >= 0 && id <= max) {
		while (n > 0 && p) {
			n -= IDR_BITS;
			*paa++ = p;
			p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
		}
 
		if (p) {
			error = fn(id, (void *)p, data);
			if (error)
				break;
		}
 
		id += 1 << n;
		while (n < fls(id)) {
			n += IDR_BITS;
			p = *--paa;
		}
	}
 
	return error;
}
EXPORT_SYMBOL(idr_for_each);
 
/**
 * idr_get_next - lookup next object of id to given id.
 * @idp: idr handle
 * @nextidp:  pointer to lookup key
 *
 * Returns pointer to registered object with id, which is next number to
 * given id. After being looked up, *@nextidp will be updated for the next
 * iteration.
 *
 * This function can be called under rcu_read_lock(), given that the leaf
 * pointers lifetimes are correctly managed.
 */
void *idr_get_next(struct idr *idp, int *nextidp)
{
	struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
	struct idr_layer **paa = &pa[0];
	int id = *nextidp;
	int n, max;
 
	/* find first ent */
	p = rcu_dereference_raw(idp->top);
	if (!p)
		return NULL;
	n = (p->layer + 1) * IDR_BITS;
	max = idr_max(p->layer + 1);
 
	while (id >= 0 && id <= max) {
		while (n > 0 && p) {
			n -= IDR_BITS;
			*paa++ = p;
			p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
		}
 
		if (p) {
			*nextidp = id;
			return p;
		}
 
		/*
		 * Proceed to the next layer at the current level.  Unlike
		 * idr_for_each(), @id isn't guaranteed to be aligned to
		 * layer boundary at this point and adding 1 << n may
		 * incorrectly skip IDs.  Make sure we jump to the
		 * beginning of the next layer using round_up().
		 */
		id = round_up(id + 1, 1 << n);
		while (n < fls(id)) {
			n += IDR_BITS;
			p = *--paa;
		}
	}
	return NULL;
}
EXPORT_SYMBOL(idr_get_next);
 
 
/**
 * idr_replace - replace pointer for given id
 * @idp: idr handle
 * @ptr: pointer you want associated with the id
 * @id: lookup key
 *
 * Replace the pointer registered with an id and return the old value.
 * A %-ENOENT return indicates that @id was not found.
 * A %-EINVAL return indicates that @id was not within valid constraints.
 *
 * The caller must serialize with writers.
 */
void *idr_replace(struct idr *idp, void *ptr, int id)
{
	int n;
	struct idr_layer *p, *old_p;
 
	if (id < 0)
		return ERR_PTR(-EINVAL);
 
	p = idp->top;
	if (!p)
		return ERR_PTR(-EINVAL);
 
	n = (p->layer+1) * IDR_BITS;
 
	if (id >= (1 << n))
		return ERR_PTR(-EINVAL);
 
	n -= IDR_BITS;
	while ((n > 0) && p) {
		p = p->ary[(id >> n) & IDR_MASK];
		n -= IDR_BITS;
	}
 
	n = id & IDR_MASK;
	if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
		return ERR_PTR(-ENOENT);
 
	old_p = p->ary[n];
	rcu_assign_pointer(p->ary[n], ptr);
 
	return old_p;
}
EXPORT_SYMBOL(idr_replace);
 
 
 
 
 
void __init idr_init_cache(void)
{
    //idr_layer_cache = kmem_cache_create("idr_layer_cache",
    //           sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
}
 
/**
 * 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)
{
	memset(idp, 0, sizeof(struct idr));
	spin_lock_init(&idp->lock);
}
EXPORT_SYMBOL(idr_init);
 
 
/**
 * DOC: IDA description
 * IDA - IDR based ID allocator
 *
 * This is id allocator without id -> pointer translation.  Memory
 * usage is much lower than full blown idr because each id only
 * occupies a bit.  ida uses a custom leaf node which contains
 * IDA_BITMAP_BITS slots.
 *
 * 2007-04-25  written by Tejun Heo 
 */
 
static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
{
	unsigned long flags;
 
	if (!ida->free_bitmap) {
		spin_lock_irqsave(&ida->idr.lock, flags);
		if (!ida->free_bitmap) {
			ida->free_bitmap = bitmap;
			bitmap = NULL;
		}
		spin_unlock_irqrestore(&ida->idr.lock, flags);
	}
 
	kfree(bitmap);
}
 
/**
 * ida_pre_get - reserve resources for ida allocation
 * @ida:	ida handle
 * @gfp_mask:	memory allocation flag
 *
 * 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 ida_pre_get(struct ida *ida, gfp_t gfp_mask)
{
	/* allocate idr_layers */
	if (!__idr_pre_get(&ida->idr, gfp_mask))
		return 0;
 
	/* allocate free_bitmap */
	if (!ida->free_bitmap) {
		struct ida_bitmap *bitmap;
 
		bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
		if (!bitmap)
			return 0;
 
		free_bitmap(ida, bitmap);
	}
 
	return 1;
}
EXPORT_SYMBOL(ida_pre_get);
 
/**
 * ida_get_new_above - allocate new ID above or equal to a start id
 * @ida:	ida handle
 * @starting_id: id to start search at
 * @p_id:	pointer to the allocated handle
 *
 * Allocate new ID above or equal to @starting_id.  It should be called
 * with any required locks.
 *
 * If memory is required, it will return %-EAGAIN, you should unlock
 * and go back to the ida_pre_get() call.  If the ida is full, it will
 * return %-ENOSPC.
 *
 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
 */
int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
{
	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
	struct ida_bitmap *bitmap;
	unsigned long flags;
	int idr_id = starting_id / IDA_BITMAP_BITS;
	int offset = starting_id % IDA_BITMAP_BITS;
	int t, id;
 
 restart:
	/* get vacant slot */
	t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
	if (t < 0)
		return t == -ENOMEM ? -EAGAIN : t;
 
	if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
		return -ENOSPC;
 
	if (t != idr_id)
		offset = 0;
	idr_id = t;
 
	/* if bitmap isn't there, create a new one */
	bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
	if (!bitmap) {
		spin_lock_irqsave(&ida->idr.lock, flags);
		bitmap = ida->free_bitmap;
		ida->free_bitmap = NULL;
		spin_unlock_irqrestore(&ida->idr.lock, flags);
 
		if (!bitmap)
			return -EAGAIN;
 
		memset(bitmap, 0, sizeof(struct ida_bitmap));
		rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
				(void *)bitmap);
		pa[0]->count++;
	}
 
	/* lookup for empty slot */
	t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
	if (t == IDA_BITMAP_BITS) {
		/* no empty slot after offset, continue to the next chunk */
		idr_id++;
		offset = 0;
		goto restart;
	}
 
	id = idr_id * IDA_BITMAP_BITS + t;
	if (id >= MAX_IDR_BIT)
		return -ENOSPC;
 
	__set_bit(t, bitmap->bitmap);
	if (++bitmap->nr_busy == IDA_BITMAP_BITS)
		idr_mark_full(pa, idr_id);
 
	*p_id = id;
 
	/* Each leaf node can handle nearly a thousand slots and the
	 * whole idea of ida is to have small memory foot print.
	 * Throw away extra resources one by one after each successful
	 * allocation.
	 */
	if (ida->idr.id_free_cnt || ida->free_bitmap) {
		struct idr_layer *p = get_from_free_list(&ida->idr);
		if (p)
			kfree(p);
	}
 
	return 0;
}
EXPORT_SYMBOL(ida_get_new_above);
 
/**
 * ida_remove - remove the given ID
 * @ida:	ida handle
 * @id:		ID to free
 */
void ida_remove(struct ida *ida, int id)
{
	struct idr_layer *p = ida->idr.top;
	int shift = (ida->idr.layers - 1) * IDR_BITS;
	int idr_id = id / IDA_BITMAP_BITS;
	int offset = id % IDA_BITMAP_BITS;
	int n;
	struct ida_bitmap *bitmap;
 
	/* clear full bits while looking up the leaf idr_layer */
	while ((shift > 0) && p) {
		n = (idr_id >> shift) & IDR_MASK;
		__clear_bit(n, p->bitmap);
		p = p->ary[n];
		shift -= IDR_BITS;
	}
 
	if (p == NULL)
		goto err;
 
	n = idr_id & IDR_MASK;
	__clear_bit(n, p->bitmap);
 
	bitmap = (void *)p->ary[n];
	if (!test_bit(offset, bitmap->bitmap))
		goto err;
 
	/* update bitmap and remove it if empty */
	__clear_bit(offset, bitmap->bitmap);
	if (--bitmap->nr_busy == 0) {
		__set_bit(n, p->bitmap);	/* to please idr_remove() */
		idr_remove(&ida->idr, idr_id);
		free_bitmap(ida, bitmap);
	}
 
	return;
 
 err:
	WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
}
EXPORT_SYMBOL(ida_remove);
 
/**
 * ida_destroy - release all cached layers within an ida tree
 * @ida:		ida handle
 */
void ida_destroy(struct ida *ida)
{
	idr_destroy(&ida->idr);
	kfree(ida->free_bitmap);
}
EXPORT_SYMBOL(ida_destroy);
 
/**
 * ida_simple_get - get a new id.
 * @ida: the (initialized) ida.
 * @start: the minimum id (inclusive, < 0x8000000)
 * @end: the maximum id (exclusive, < 0x8000000 or 0)
 * @gfp_mask: memory allocation flags
 *
 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
 * On memory allocation failure, returns -ENOMEM.
 *
 * Use ida_simple_remove() to get rid of an id.
 */
int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
		   gfp_t gfp_mask)
{
	int ret, id;
	unsigned int max;
	unsigned long flags;
 
	BUG_ON((int)start < 0);
	BUG_ON((int)end < 0);
 
	if (end == 0)
		max = 0x80000000;
	else {
		BUG_ON(end < start);
		max = end - 1;
	}
 
again:
	if (!ida_pre_get(ida, gfp_mask))
		return -ENOMEM;
 
	spin_lock_irqsave(&simple_ida_lock, flags);
	ret = ida_get_new_above(ida, start, &id);
	if (!ret) {
		if (id > max) {
			ida_remove(ida, id);
			ret = -ENOSPC;
		} else {
			ret = id;
		}
	}
	spin_unlock_irqrestore(&simple_ida_lock, flags);
 
	if (unlikely(ret == -EAGAIN))
		goto again;
 
	return ret;
}
EXPORT_SYMBOL(ida_simple_get);
 
/**
 * ida_simple_remove - remove an allocated id.
 * @ida: the (initialized) ida.
 * @id: the id returned by ida_simple_get.
 */
void ida_simple_remove(struct ida *ida, unsigned int id)
{
	unsigned long flags;
 
	BUG_ON((int)id < 0);
	spin_lock_irqsave(&simple_ida_lock, flags);
	ida_remove(ida, id);
	spin_unlock_irqrestore(&simple_ida_lock, flags);
}
EXPORT_SYMBOL(ida_simple_remove);
 
/**
 * ida_init - initialize ida handle
 * @ida:	ida handle
 *
 * This function is use to set up the handle (@ida) that you will pass
 * to the rest of the functions.
 */
void ida_init(struct ida *ida)
{
	memset(ida, 0, sizeof(struct ida));
	idr_init(&ida->idr);
 
}
EXPORT_SYMBOL(ida_init);
 
 
 
unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
{
        const unsigned long *p = addr;
        unsigned long result = 0;
        unsigned long tmp;
 
        while (size & ~(BITS_PER_LONG-1)) {
                if ((tmp = *(p++)))
                        goto found;
                result += BITS_PER_LONG;
                size -= BITS_PER_LONG;
        }
        if (!size)
                return result;
 
        tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
        if (tmp == 0UL)         /* Are any bits set? */
                return result + size;   /* Nope. */
found:
        return result + __ffs(tmp);
}
 
unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
                            unsigned long offset)
{
        const unsigned long *p = addr + BITOP_WORD(offset);
        unsigned long result = offset & ~(BITS_PER_LONG-1);
        unsigned long tmp;
 
        if (offset >= size)
                return size;
        size -= result;
        offset %= BITS_PER_LONG;
        if (offset) {
                tmp = *(p++);
                tmp &= (~0UL << offset);
                if (size < BITS_PER_LONG)
                        goto found_first;
                if (tmp)
                        goto found_middle;
                size -= BITS_PER_LONG;
                result += BITS_PER_LONG;
        }
        while (size & ~(BITS_PER_LONG-1)) {
                if ((tmp = *(p++)))
                        goto found_middle;
                result += BITS_PER_LONG;
                size -= BITS_PER_LONG;
        }
        if (!size)
                return result;
        tmp = *p;
 
found_first:
        tmp &= (~0UL >> (BITS_PER_LONG - size));
        if (tmp == 0UL)         /* Are any bits set? */
                return result + size;   /* Nope. */
found_middle:
        return result + __ffs(tmp);
}
 
unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
                                 unsigned long offset)
{
        const unsigned long *p = addr + BITOP_WORD(offset);
        unsigned long result = offset & ~(BITS_PER_LONG-1);
        unsigned long tmp;
 
        if (offset >= size)
                return size;
        size -= result;
        offset %= BITS_PER_LONG;
        if (offset) {
                tmp = *(p++);
                tmp |= ~0UL >> (BITS_PER_LONG - offset);
                if (size < BITS_PER_LONG)
                        goto found_first;
                if (~tmp)
                        goto found_middle;
                size -= BITS_PER_LONG;
                result += BITS_PER_LONG;
        }
        while (size & ~(BITS_PER_LONG-1)) {
                if (~(tmp = *(p++)))
                        goto found_middle;
                result += BITS_PER_LONG;
                size -= BITS_PER_LONG;
        }
        if (!size)
                return result;
        tmp = *p;
 
found_first:
        tmp |= ~0UL << size;
        if (tmp == ~0UL)        /* Are any bits zero? */
                return result + size;   /* Nope. */
found_middle:
        return result + ffz(tmp);
}
 
unsigned int hweight32(unsigned int w)
{
        unsigned int res = w - ((w >> 1) & 0x55555555);
        res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
        res = (res + (res >> 4)) & 0x0F0F0F0F;
        res = res + (res >> 8);
        return (res + (res >> 16)) & 0x000000FF;
}

Rev 4065	Rev 4103
1	/*	1	/*
2	* 2002-10-18 written by Jim Houston jim.houston@ccur.com	2	* 2002-10-18 written by Jim Houston jim.houston@ccur.com
3	* Copyright (C) 2002 by Concurrent Computer Corporation	3	* Copyright (C) 2002 by Concurrent Computer Corporation
4	* Distributed under the GNU GPL license version 2.	4	* Distributed under the GNU GPL license version 2.
5	*	5	*
6	* Modified by George Anzinger to reuse immediately and to use	6	* Modified by George Anzinger to reuse immediately and to use
7	* find bit instructions. Also removed _irq on spinlocks.	7	* find bit instructions. Also removed _irq on spinlocks.
8	*	8	*
9	* Modified by Nadia Derbey to make it RCU safe.	9	* Modified by Nadia Derbey to make it RCU safe.
10	*	10	*
11	* Small id to pointer translation service.	11	* Small id to pointer translation service.
12	*	12	*
13	* It uses a radix tree like structure as a sparse array indexed	13	* It uses a radix tree like structure as a sparse array indexed
14	* by the id to obtain the pointer. The bitmap makes allocating	14	* by the id to obtain the pointer. The bitmap makes allocating
15	* a new id quick.	15	* a new id quick.
16	*	16	*
17	* You call it to allocate an id (an int) an associate with that id a	17	* You call it to allocate an id (an int) an associate with that id a
18	* pointer or what ever, we treat it as a (void *). You can pass this	18	* pointer or what ever, we treat it as a (void *). You can pass this
19	* id to a user for him to pass back at a later time. You then pass	19	* id to a user for him to pass back at a later time. You then pass
20	* that id to this code and it returns your pointer.	20	* that id to this code and it returns your pointer.
21		21
22	* You can release ids at any time. When all ids are released, most of	22	* You can release ids at any time. When all ids are released, most of
23	* the memory is returned (we keep MAX_IDR_FREE) in a local pool so we	23	* the memory is returned (we keep MAX_IDR_FREE) in a local pool so we
24	* don't need to go to the memory "store" during an id allocate, just	24	* don't need to go to the memory "store" during an id allocate, just
25	* so you don't need to be too concerned about locking and conflicts	25	* so you don't need to be too concerned about locking and conflicts
26	* with the slab allocator.	26	* with the slab allocator.
27	*/	27	*/
28		28
29	#include	29	#include
30	#include	30	#include
31	#include	31	#include
32	#include	32	#include
33	#include	33	#include
34	//#include	34	//#include
-		35
-		36	static inline void * __must_check ERR_PTR(long error)
-		37	{
-		38	return (void *) error;
-		39	}
35		40
36	unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,	41	unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
37	unsigned long offset);	42	unsigned long offset);
38		43
39		44
40	#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)	45	#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
41	#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)	46	#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
42		47
43	/* Leave the possibility of an incomplete final layer */	48	/* Leave the possibility of an incomplete final layer */
44	#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)	49	#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
45		50
46	/* Number of id_layer structs to leave in free list */	51	/* Number of id_layer structs to leave in free list */
47	#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)	52	#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
48		53
49	static struct idr_layer *idr_preload_head;	54	static struct idr_layer *idr_preload_head;
50	static int idr_preload_cnt;	55	static int idr_preload_cnt;
-		56
51		57	static DEFINE_SPINLOCK(simple_ida_lock);
52		58
53	/* the maximum ID which can be allocated given idr->layers */	59	/* the maximum ID which can be allocated given idr->layers */
54	static int idr_max(int layers)	60	static int idr_max(int layers)
55	{	61	{
56	int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);	62	int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
57		63
58	return (1 << bits) - 1;	64	return (1 << bits) - 1;
59	}	65	}
60		66
61	/*	67	/*
62	* Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is	68	* Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
63	* all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and	69	* all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
64	* so on.	70	* so on.
65	*/	71	*/
66	static int idr_layer_prefix_mask(int layer)	72	static int idr_layer_prefix_mask(int layer)
67	{	73	{
68	return ~idr_max(layer + 1);	74	return ~idr_max(layer + 1);
69	}	75	}
70		76
71	static struct idr_layer get_from_free_list(struct idr idp)	77	static struct idr_layer get_from_free_list(struct idr idp)
72	{	78	{
73	struct idr_layer *p;	79	struct idr_layer *p;
74	unsigned long flags;	80	unsigned long flags;
75		81
76	spin_lock_irqsave(&idp->lock, flags);	82	spin_lock_irqsave(&idp->lock, flags);
77	if ((p = idp->id_free)) {	83	if ((p = idp->id_free)) {
78	idp->id_free = p->ary[0];	84	idp->id_free = p->ary[0];
79	idp->id_free_cnt--;	85	idp->id_free_cnt--;
80	p->ary[0] = NULL;	86	p->ary[0] = NULL;
81	}	87	}
82	spin_unlock_irqrestore(&idp->lock, flags);	88	spin_unlock_irqrestore(&idp->lock, flags);
83	return(p);	89	return(p);
84	}	90	}
85		91
86	/**	92	/**
87	* idr_layer_alloc - allocate a new idr_layer	93	* idr_layer_alloc - allocate a new idr_layer
88	* @gfp_mask: allocation mask	94	* @gfp_mask: allocation mask
89	* @layer_idr: optional idr to allocate from	95	* @layer_idr: optional idr to allocate from
90	*	96	*
91	* If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch	97	* If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
92	* one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch	98	* one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
93	* an idr_layer from @idr->id_free.	99	* an idr_layer from @idr->id_free.
94	*	100	*
95	* @layer_idr is to maintain backward compatibility with the old alloc	101	* @layer_idr is to maintain backward compatibility with the old alloc
96	* interface - idr_pre_get() and idr_get_new*() - and will be removed	102	* interface - idr_pre_get() and idr_get_new*() - and will be removed
97	* together with per-pool preload buffer.	103	* together with per-pool preload buffer.
98	*/	104	*/
99	static struct idr_layer idr_layer_alloc(gfp_t gfp_mask, struct idr layer_idr)	105	static struct idr_layer idr_layer_alloc(gfp_t gfp_mask, struct idr layer_idr)
100	{	106	{
101	struct idr_layer *new;	107	struct idr_layer *new;
102		108
103	/* this is the old path, bypass to get_from_free_list() */	109	/* this is the old path, bypass to get_from_free_list() */
104	if (layer_idr)	110	if (layer_idr)
105	return get_from_free_list(layer_idr);	111	return get_from_free_list(layer_idr);
106		112
107	/* try to allocate directly from kmem_cache */	113	/* try to allocate directly from kmem_cache */
108	new = kzalloc(sizeof(struct idr_layer), gfp_mask);	114	new = kzalloc(sizeof(struct idr_layer), gfp_mask);
109	if (new)	115	if (new)
110	return new;	116	return new;
111		117
112		118
113	new = idr_preload_head;	119	new = idr_preload_head;
114	if (new) {	120	if (new) {
115	idr_preload_head = new->ary[0];	121	idr_preload_head = new->ary[0];
116	idr_preload_cnt--;	122	idr_preload_cnt--;
117	new->ary[0] = NULL;	123	new->ary[0] = NULL;
118	}	124	}
119	preempt_enable();	125	preempt_enable();
120	return new;	126	return new;
121	}	127	}
122		128
123	static void idr_layer_rcu_free(struct rcu_head *head)	129	static void idr_layer_rcu_free(struct rcu_head *head)
124	{	130	{
125	struct idr_layer *layer;	131	struct idr_layer *layer;
126		132
127	layer = container_of(head, struct idr_layer, rcu_head);	133	layer = container_of(head, struct idr_layer, rcu_head);
128	kfree(layer);	134	kfree(layer);
129	}	135	}
130		136
131	static inline void free_layer(struct idr idr, struct idr_layer p)	137	static inline void free_layer(struct idr idr, struct idr_layer p)
132	{	138	{
133	if (idr->hint && idr->hint == p)	139	if (idr->hint && idr->hint == p)
134	RCU_INIT_POINTER(idr->hint, NULL);	140	RCU_INIT_POINTER(idr->hint, NULL);
135	idr_layer_rcu_free(&p->rcu_head);	141	idr_layer_rcu_free(&p->rcu_head);
136	}	142	}
137		143
138	/* only called when idp->lock is held */	144	/* only called when idp->lock is held */
139	static void __move_to_free_list(struct idr idp, struct idr_layer p)	145	static void __move_to_free_list(struct idr idp, struct idr_layer p)
140	{	146	{
141	p->ary[0] = idp->id_free;	147	p->ary[0] = idp->id_free;
142	idp->id_free = p;	148	idp->id_free = p;
143	idp->id_free_cnt++;	149	idp->id_free_cnt++;
144	}	150	}
145		151
146	static void move_to_free_list(struct idr idp, struct idr_layer p)	152	static void move_to_free_list(struct idr idp, struct idr_layer p)
147	{	153	{
148	unsigned long flags;	154	unsigned long flags;
149		155
150	/*	156	/*
151	* Depends on the return element being zeroed.	157	* Depends on the return element being zeroed.
152	*/	158	*/
153	spin_lock_irqsave(&idp->lock, flags);	159	spin_lock_irqsave(&idp->lock, flags);
154	__move_to_free_list(idp, p);	160	__move_to_free_list(idp, p);
155	spin_unlock_irqrestore(&idp->lock, flags);	161	spin_unlock_irqrestore(&idp->lock, flags);
156	}	162	}
157		163
158	static void idr_mark_full(struct idr_layer **pa, int id)	164	static void idr_mark_full(struct idr_layer **pa, int id)
159	{	165	{
160	struct idr_layer *p = pa[0];	166	struct idr_layer *p = pa[0];
161	int l = 0;	167	int l = 0;
162		168
163	__set_bit(id & IDR_MASK, p->bitmap);	169	__set_bit(id & IDR_MASK, p->bitmap);
164	/*	170	/*
165	* If this layer is full mark the bit in the layer above to	171	* If this layer is full mark the bit in the layer above to
166	* show that this part of the radix tree is full. This may	172	* show that this part of the radix tree is full. This may
167	* complete the layer above and require walking up the radix	173	* complete the layer above and require walking up the radix
168	* tree.	174	* tree.
169	*/	175	*/
170	while (bitmap_full(p->bitmap, IDR_SIZE)) {	176	while (bitmap_full(p->bitmap, IDR_SIZE)) {
171	if (!(p = pa[++l]))	177	if (!(p = pa[++l]))
172	break;	178	break;
173	id = id >> IDR_BITS;	179	id = id >> IDR_BITS;
174	__set_bit((id & IDR_MASK), p->bitmap);	180	__set_bit((id & IDR_MASK), p->bitmap);
175	}	181	}
176	}	182	}
177		183
178	int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)	184	int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
179	{	185	{
180	while (idp->id_free_cnt < MAX_IDR_FREE) {	186	while (idp->id_free_cnt < MAX_IDR_FREE) {
181	struct idr_layer *new;	187	struct idr_layer *new;
182	new = kzalloc(sizeof(struct idr_layer), gfp_mask);	188	new = kzalloc(sizeof(struct idr_layer), gfp_mask);
183	if (new == NULL)	189	if (new == NULL)
184	return (0);	190	return (0);
185	move_to_free_list(idp, new);	191	move_to_free_list(idp, new);
186	}	192	}
187	return 1;	193	return 1;
188	}	194	}
189	EXPORT_SYMBOL(__idr_pre_get);	195	EXPORT_SYMBOL(__idr_pre_get);
190		196
191	/**	197	/**
192	* sub_alloc - try to allocate an id without growing the tree depth	198	* sub_alloc - try to allocate an id without growing the tree depth
193	* @idp: idr handle	199	* @idp: idr handle
194	* @starting_id: id to start search at	200	* @starting_id: id to start search at
195	* @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer	201	* @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
196	* @gfp_mask: allocation mask for idr_layer_alloc()	202	* @gfp_mask: allocation mask for idr_layer_alloc()
197	* @layer_idr: optional idr passed to idr_layer_alloc()	203	* @layer_idr: optional idr passed to idr_layer_alloc()
198	*	204	*
199	* Allocate an id in range [@starting_id, INT_MAX] from @idp without	205	* Allocate an id in range [@starting_id, INT_MAX] from @idp without
200	* growing its depth. Returns	206	* growing its depth. Returns
201	*	207	*
202	* the allocated id >= 0 if successful,	208	* the allocated id >= 0 if successful,
203	* -EAGAIN if the tree needs to grow for allocation to succeed,	209	* -EAGAIN if the tree needs to grow for allocation to succeed,
204	* -ENOSPC if the id space is exhausted,	210	* -ENOSPC if the id space is exhausted,
205	* -ENOMEM if more idr_layers need to be allocated.	211	* -ENOMEM if more idr_layers need to be allocated.
206	*/	212	*/
207	static int sub_alloc(struct idr idp, int starting_id, struct idr_layer **pa,	213	static int sub_alloc(struct idr idp, int starting_id, struct idr_layer **pa,
208	gfp_t gfp_mask, struct idr *layer_idr)	214	gfp_t gfp_mask, struct idr *layer_idr)
209	{	215	{
210	int n, m, sh;	216	int n, m, sh;
211	struct idr_layer p, new;	217	struct idr_layer p, new;
212	int l, id, oid;	218	int l, id, oid;
213		219
214	id = *starting_id;	220	id = *starting_id;
215	restart:	221	restart:
216	p = idp->top;	222	p = idp->top;
217	l = idp->layers;	223	l = idp->layers;
218	pa[l--] = NULL;	224	pa[l--] = NULL;
219	while (1) {	225	while (1) {
220	/*	226	/*
221	* We run around this while until we reach the leaf node...	227	* We run around this while until we reach the leaf node...
222	*/	228	*/
223	n = (id >> (IDR_BITS*l)) & IDR_MASK;	229	n = (id >> (IDR_BITS*l)) & IDR_MASK;
224	m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);	230	m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
225	if (m == IDR_SIZE) {	231	if (m == IDR_SIZE) {
226	/* no space available go back to previous layer. */	232	/* no space available go back to previous layer. */
227	l++;	233	l++;
228	oid = id;	234	oid = id;
229	id = (id \| ((1 << (IDR_BITS * l)) - 1)) + 1;	235	id = (id \| ((1 << (IDR_BITS * l)) - 1)) + 1;
230		236
231	/* if already at the top layer, we need to grow */	237	/* if already at the top layer, we need to grow */
232	if (id >= 1 << (idp->layers * IDR_BITS)) {	238	if (id >= 1 << (idp->layers * IDR_BITS)) {
233	*starting_id = id;	239	*starting_id = id;
234	return -EAGAIN;	240	return -EAGAIN;
235	}	241	}
236	p = pa[l];	242	p = pa[l];
237	BUG_ON(!p);	243	BUG_ON(!p);
238		244
239	/* If we need to go up one layer, continue the	245	/* If we need to go up one layer, continue the
240	* loop; otherwise, restart from the top.	246	* loop; otherwise, restart from the top.
241	*/	247	*/
242	sh = IDR_BITS * (l + 1);	248	sh = IDR_BITS * (l + 1);
243	if (oid >> sh == id >> sh)	249	if (oid >> sh == id >> sh)
244	continue;	250	continue;
245	else	251	else
246	goto restart;	252	goto restart;
247	}	253	}
248	if (m != n) {	254	if (m != n) {
249	sh = IDR_BITS*l;	255	sh = IDR_BITS*l;
250	id = ((id >> sh) ^ n ^ m) << sh;	256	id = ((id >> sh) ^ n ^ m) << sh;
251	}	257	}
252	if ((id >= MAX_IDR_BIT) \|\| (id < 0))	258	if ((id >= MAX_IDR_BIT) \|\| (id < 0))
253	return -ENOSPC;	259	return -ENOSPC;
254	if (l == 0)	260	if (l == 0)
255	break;	261	break;
256	/*	262	/*
257	* Create the layer below if it is missing.	263	* Create the layer below if it is missing.
258	*/	264	*/
259	if (!p->ary[m]) {	265	if (!p->ary[m]) {
260	new = idr_layer_alloc(gfp_mask, layer_idr);	266	new = idr_layer_alloc(gfp_mask, layer_idr);
261	if (!new)	267	if (!new)
262	return -ENOMEM;	268	return -ENOMEM;
263	new->layer = l-1;	269	new->layer = l-1;
264	new->prefix = id & idr_layer_prefix_mask(new->layer);	270	new->prefix = id & idr_layer_prefix_mask(new->layer);
265	rcu_assign_pointer(p->ary[m], new);	271	rcu_assign_pointer(p->ary[m], new);
266	p->count++;	272	p->count++;
267	}	273	}
268	pa[l--] = p;	274	pa[l--] = p;
269	p = p->ary[m];	275	p = p->ary[m];
270	}	276	}
271		277
272	pa[l] = p;	278	pa[l] = p;
273	return id;	279	return id;
274	}	280	}
275		281
276	static int idr_get_empty_slot(struct idr *idp, int starting_id,	282	static int idr_get_empty_slot(struct idr *idp, int starting_id,
277	struct idr_layer **pa, gfp_t gfp_mask,	283	struct idr_layer **pa, gfp_t gfp_mask,
278	struct idr *layer_idr)	284	struct idr *layer_idr)
279	{	285	{
280	struct idr_layer p, new;	286	struct idr_layer p, new;
281	int layers, v, id;	287	int layers, v, id;
282	unsigned long flags;	288	unsigned long flags;
283		289
284	id = starting_id;	290	id = starting_id;
285	build_up:	291	build_up:
286	p = idp->top;	292	p = idp->top;
287	layers = idp->layers;	293	layers = idp->layers;
288	if (unlikely(!p)) {	294	if (unlikely(!p)) {
289	if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))	295	if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
290	return -ENOMEM;	296	return -ENOMEM;
291	p->layer = 0;	297	p->layer = 0;
292	layers = 1;	298	layers = 1;
293	}	299	}
294	/*	300	/*
295	* Add a new layer to the top of the tree if the requested	301	* Add a new layer to the top of the tree if the requested
296	* id is larger than the currently allocated space.	302	* id is larger than the currently allocated space.
297	*/	303	*/
298	while (id > idr_max(layers)) {	304	while (id > idr_max(layers)) {
299	layers++;	305	layers++;
300	if (!p->count) {	306	if (!p->count) {
301	/* special case: if the tree is currently empty,	307	/* special case: if the tree is currently empty,
302	* then we grow the tree by moving the top node	308	* then we grow the tree by moving the top node
303	* upwards.	309	* upwards.
304	*/	310	*/
305	p->layer++;	311	p->layer++;
306	WARN_ON_ONCE(p->prefix);	312	WARN_ON_ONCE(p->prefix);
307	continue;	313	continue;
308	}	314	}
309	if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {	315	if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
310	/*	316	/*
311	* The allocation failed. If we built part of	317	* The allocation failed. If we built part of
312	* the structure tear it down.	318	* the structure tear it down.
313	*/	319	*/
314	spin_lock_irqsave(&idp->lock, flags);	320	spin_lock_irqsave(&idp->lock, flags);
315	for (new = p; p && p != idp->top; new = p) {	321	for (new = p; p && p != idp->top; new = p) {
316	p = p->ary[0];	322	p = p->ary[0];
317	new->ary[0] = NULL;	323	new->ary[0] = NULL;
318	new->count = 0;	324	new->count = 0;
319	bitmap_clear(new->bitmap, 0, IDR_SIZE);	325	bitmap_clear(new->bitmap, 0, IDR_SIZE);
320	__move_to_free_list(idp, new);	326	__move_to_free_list(idp, new);
321	}	327	}
322	spin_unlock_irqrestore(&idp->lock, flags);	328	spin_unlock_irqrestore(&idp->lock, flags);
323	return -ENOMEM;	329	return -ENOMEM;
324	}	330	}
325	new->ary[0] = p;	331	new->ary[0] = p;
326	new->count = 1;	332	new->count = 1;
327	new->layer = layers-1;	333	new->layer = layers-1;
328	new->prefix = id & idr_layer_prefix_mask(new->layer);	334	new->prefix = id & idr_layer_prefix_mask(new->layer);
329	if (bitmap_full(p->bitmap, IDR_SIZE))	335	if (bitmap_full(p->bitmap, IDR_SIZE))
330	__set_bit(0, new->bitmap);	336	__set_bit(0, new->bitmap);
331	p = new;	337	p = new;
332	}	338	}
333	rcu_assign_pointer(idp->top, p);	339	rcu_assign_pointer(idp->top, p);
334	idp->layers = layers;	340	idp->layers = layers;
335	v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);	341	v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
336	if (v == -EAGAIN)	342	if (v == -EAGAIN)
337	goto build_up;	343	goto build_up;
338	return(v);	344	return(v);
339	}	345	}
340		346
341	/*	347	/*
342	* @id and @pa are from a successful allocation from idr_get_empty_slot().	348	* @id and @pa are from a successful allocation from idr_get_empty_slot().
343	* Install the user pointer @ptr and mark the slot full.	349	* Install the user pointer @ptr and mark the slot full.
344	*/	350	*/
345	static void idr_fill_slot(struct idr idr, void ptr, int id,	351	static void idr_fill_slot(struct idr idr, void ptr, int id,
346	struct idr_layer **pa)	352	struct idr_layer **pa)
347	{	353	{
348	/* update hint used for lookup, cleared from free_layer() */	354	/* update hint used for lookup, cleared from free_layer() */
349	rcu_assign_pointer(idr->hint, pa[0]);	355	rcu_assign_pointer(idr->hint, pa[0]);
350		356
351	rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);	357	rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
352	pa[0]->count++;	358	pa[0]->count++;
353	idr_mark_full(pa, id);	359	idr_mark_full(pa, id);
354	}	360	}
355		361
356	int __idr_get_new_above(struct idr idp, void ptr, int starting_id, int *id)	362	int __idr_get_new_above(struct idr idp, void ptr, int starting_id, int *id)
357	{	363	{
358	struct idr_layer *pa[MAX_IDR_LEVEL + 1];	364	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
359	int rv;	365	int rv;
360		366
361	rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp);	367	rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp);
362	if (rv < 0)	368	if (rv < 0)
363	return rv == -ENOMEM ? -EAGAIN : rv;	369	return rv == -ENOMEM ? -EAGAIN : rv;
364		370
365	idr_fill_slot(idp, ptr, rv, pa);	371	idr_fill_slot(idp, ptr, rv, pa);
366	*id = rv;	372	*id = rv;
367	return 0;	373	return 0;
368	}	374	}
369	EXPORT_SYMBOL(__idr_get_new_above);	375	EXPORT_SYMBOL(__idr_get_new_above);
370		376
371	/**	377	/**
372	* idr_preload - preload for idr_alloc()	378	* idr_preload - preload for idr_alloc()
373	* @gfp_mask: allocation mask to use for preloading	379	* @gfp_mask: allocation mask to use for preloading
374	*	380	*
375	* Preload per-cpu layer buffer for idr_alloc(). Can only be used from	381	* Preload per-cpu layer buffer for idr_alloc(). Can only be used from
376	* process context and each idr_preload() invocation should be matched with	382	* process context and each idr_preload() invocation should be matched with
377	* idr_preload_end(). Note that preemption is disabled while preloaded.	383	* idr_preload_end(). Note that preemption is disabled while preloaded.
378	*	384	*
379	* The first idr_alloc() in the preloaded section can be treated as if it	385	* The first idr_alloc() in the preloaded section can be treated as if it
380	* were invoked with @gfp_mask used for preloading. This allows using more	386	* were invoked with @gfp_mask used for preloading. This allows using more
381	* permissive allocation masks for idrs protected by spinlocks.	387	* permissive allocation masks for idrs protected by spinlocks.
382	*	388	*
383	* For example, if idr_alloc() below fails, the failure can be treated as	389	* For example, if idr_alloc() below fails, the failure can be treated as
384	* if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.	390	* if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
385	*	391	*
386	* idr_preload(GFP_KERNEL);	392	* idr_preload(GFP_KERNEL);
387	* spin_lock(lock);	393	* spin_lock(lock);
388	*	394	*
389	* id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);	395	* id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
390	*	396	*
391	* spin_unlock(lock);	397	* spin_unlock(lock);
392	* idr_preload_end();	398	* idr_preload_end();
393	* if (id < 0)	399	* if (id < 0)
394	* error;	400	* error;
395	*/	401	*/
396	void idr_preload(gfp_t gfp_mask)	402	void idr_preload(gfp_t gfp_mask)
397	{	403	{
398		404
399	/*	405	/*
400	* idr_alloc() is likely to succeed w/o full idr_layer buffer and	406	* idr_alloc() is likely to succeed w/o full idr_layer buffer and
401	* return value from idr_alloc() needs to be checked for failure	407	* return value from idr_alloc() needs to be checked for failure
402	* anyway. Silently give up if allocation fails. The caller can	408	* anyway. Silently give up if allocation fails. The caller can
403	* treat failures from idr_alloc() as if idr_alloc() were called	409	* treat failures from idr_alloc() as if idr_alloc() were called
404	* with @gfp_mask which should be enough.	410	* with @gfp_mask which should be enough.
405	*/	411	*/
406	while (idr_preload_cnt < MAX_IDR_FREE) {	412	while (idr_preload_cnt < MAX_IDR_FREE) {
407	struct idr_layer *new;	413	struct idr_layer *new;
408		414
409	new = kzalloc(sizeof(struct idr_layer), gfp_mask);	415	new = kzalloc(sizeof(struct idr_layer), gfp_mask);
410	if (!new)	416	if (!new)
411	break;	417	break;
412		418
413	/* link the new one to per-cpu preload list */	419	/* link the new one to per-cpu preload list */
414	new->ary[0] = idr_preload_head;	420	new->ary[0] = idr_preload_head;
415	idr_preload_head = new;	421	idr_preload_head = new;
416	idr_preload_cnt++;	422	idr_preload_cnt++;
417	}	423	}
418	}	424	}
419	EXPORT_SYMBOL(idr_preload);	425	EXPORT_SYMBOL(idr_preload);
420		426
421	/**	427	/**
422	* idr_alloc - allocate new idr entry	428	* idr_alloc - allocate new idr entry
423	* @idr: the (initialized) idr	429	* @idr: the (initialized) idr
424	* @ptr: pointer to be associated with the new id	430	* @ptr: pointer to be associated with the new id
425	* @start: the minimum id (inclusive)	431	* @start: the minimum id (inclusive)
426	* @end: the maximum id (exclusive, <= 0 for max)	432	* @end: the maximum id (exclusive, <= 0 for max)
427	* @gfp_mask: memory allocation flags	433	* @gfp_mask: memory allocation flags
428	*	434	*
429	* Allocate an id in [start, end) and associate it with @ptr. If no ID is	435	* Allocate an id in [start, end) and associate it with @ptr. If no ID is
430	* available in the specified range, returns -ENOSPC. On memory allocation	436	* available in the specified range, returns -ENOSPC. On memory allocation
431	* failure, returns -ENOMEM.	437	* failure, returns -ENOMEM.
432	*	438	*
433	* Note that @end is treated as max when <= 0. This is to always allow	439	* Note that @end is treated as max when <= 0. This is to always allow
434	* using @start + N as @end as long as N is inside integer range.	440	* using @start + N as @end as long as N is inside integer range.
435	*	441	*
436	* The user is responsible for exclusively synchronizing all operations	442	* The user is responsible for exclusively synchronizing all operations
437	* which may modify @idr. However, read-only accesses such as idr_find()	443	* which may modify @idr. However, read-only accesses such as idr_find()
438	* or iteration can be performed under RCU read lock provided the user	444	* or iteration can be performed under RCU read lock provided the user
439	* destroys @ptr in RCU-safe way after removal from idr.	445	* destroys @ptr in RCU-safe way after removal from idr.
440	*/	446	*/
441	int idr_alloc(struct idr idr, void ptr, int start, int end, gfp_t gfp_mask)	447	int idr_alloc(struct idr idr, void ptr, int start, int end, gfp_t gfp_mask)
442	{	448	{
443	int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */	449	int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
444	struct idr_layer *pa[MAX_IDR_LEVEL + 1];	450	struct idr_layer *pa[MAX_IDR_LEVEL + 1];
445	int id;	451	int id;
446		452
447	/* sanity checks */	453	/* sanity checks */
448	if (WARN_ON_ONCE(start < 0))	454	if (WARN_ON_ONCE(start < 0))
449	return -EINVAL;	455	return -EINVAL;
450	if (unlikely(max < start))	456	if (unlikely(max < start))
451	return -ENOSPC;	457	return -ENOSPC;
452		458
453	/* allocate id */	459	/* allocate id */
454	id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);	460	id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
455	if (unlikely(id < 0))	461	if (unlikely(id < 0))
456	return id;	462	return id;
457	if (unlikely(id > max))	463	if (unlikely(id > max))
458	return -ENOSPC;	464	return -ENOSPC;
459		465
460	idr_fill_slot(idr, ptr, id, pa);	466	idr_fill_slot(idr, ptr, id, pa);
461	return id;	467	return id;
462	}	468	}
463	EXPORT_SYMBOL_GPL(idr_alloc);	469	EXPORT_SYMBOL_GPL(idr_alloc);
-		470
-		471	/**
-		472	* idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
-		473	* @idr: the (initialized) idr
-		474	* @ptr: pointer to be associated with the new id
-		475	* @start: the minimum id (inclusive)
-		476	* @end: the maximum id (exclusive, <= 0 for max)
-		477	* @gfp_mask: memory allocation flags
-		478	*
-		479	* Essentially the same as idr_alloc, but prefers to allocate progressively
-		480	* higher ids if it can. If the "cur" counter wraps, then it will start again
-		481	* at the "start" end of the range and allocate one that has already been used.
-		482	*/
-		483	int idr_alloc_cyclic(struct idr idr, void ptr, int start, int end,
-		484	gfp_t gfp_mask)
-		485	{
-		486	int id;
-		487
-		488	id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
-		489	if (id == -ENOSPC)
-		490	id = idr_alloc(idr, ptr, start, end, gfp_mask);
-		491
-		492	if (likely(id >= 0))
-		493	idr->cur = id + 1;
-		494	return id;
-		495	}
-		496	EXPORT_SYMBOL(idr_alloc_cyclic);
464		497
465	static void idr_remove_warning(int id)	498	static void idr_remove_warning(int id)
466	{	499	{
467	WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);	500	WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);

Subversion Repositories Kolibri OS

(root)/drivers/ddk/linux/idr.c – Rev 4065 → 4103