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/*

 * Copyright (c) 2006 Ondrej Palkovsky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup genericmm

 * @{

 */

/**

 * @file

 * @brief	Slab allocator.

 *

 * The slab allocator is closely modelled after OpenSolaris slab allocator.

 * @see http://www.usenix.org/events/usenix01/full_papers/bonwick/bonwick_html/

 *

 * with the following exceptions:

 * @li empty slabs are deallocated immediately 

 *     (in Linux they are kept in linked list, in Solaris ???)

 * @li empty magazines are deallocated when not needed

 *     (in Solaris they are held in linked list in slab cache)

 *

 * Following features are not currently supported but would be easy to do:

 * @li cache coloring

 * @li dynamic magazine growing (different magazine sizes are already

 *     supported, but we would need to adjust allocation strategy)

 *

 * The slab allocator supports per-CPU caches ('magazines') to facilitate

 * good SMP scaling. 

 *

 * When a new object is being allocated, it is first checked, if it is 

 * available in a CPU-bound magazine. If it is not found there, it is

 * allocated from a CPU-shared slab - if a partially full one is found,

 * it is used, otherwise a new one is allocated. 

 *

 * When an object is being deallocated, it is put to a CPU-bound magazine.

 * If there is no such magazine, a new one is allocated (if this fails, 

 * the object is deallocated into slab). If the magazine is full, it is

 * put into cpu-shared list of magazines and a new one is allocated.

 *

 * The CPU-bound magazine is actually a pair of magazines in order to avoid

 * thrashing when somebody is allocating/deallocating 1 item at the magazine

 * size boundary. LIFO order is enforced, which should avoid fragmentation

 * as much as possible. 

 *  

 * Every cache contains list of full slabs and list of partially full slabs.

 * Empty slabs are immediately freed (thrashing will be avoided because

 * of magazines). 

 *

 * The slab information structure is kept inside the data area, if possible.

 * The cache can be marked that it should not use magazines. This is used

 * only for slab related caches to avoid deadlocks and infinite recursion

 * (the slab allocator uses itself for allocating all it's control structures).

 *

 * The slab allocator allocates a lot of space and does not free it. When

 * the frame allocator fails to allocate a frame, it calls slab_reclaim().

 * It tries 'light reclaim' first, then brutal reclaim. The light reclaim

 * releases slabs from cpu-shared magazine-list, until at least 1 slab 

 * is deallocated in each cache (this algorithm should probably change).

 * The brutal reclaim removes all cached objects, even from CPU-bound

 * magazines.

 *

 * @todo

 * For better CPU-scaling the magazine allocation strategy should

 * be extended. Currently, if the cache does not have magazine, it asks

 * for non-cpu cached magazine cache to provide one. It might be feasible

 * to add cpu-cached magazine cache (which would allocate it's magazines

 * from non-cpu-cached mag. cache). This would provide a nice per-cpu

 * buffer. The other possibility is to use the per-cache 

 * 'empty-magazine-list', which decreases competing for 1 per-system

 * magazine cache.

 *

 * @todo

 * it might be good to add granularity of locks even to slab level,

 * we could then try_spinlock over all partial slabs and thus improve

 * scalability even on slab level

 */

#include <synch/spinlock.h>

#include <mm/slab.h>

#include <adt/list.h>

#include <memstr.h>

#include <align.h>

#include <mm/frame.h>

#include <config.h>

#include <print.h>

#include <arch.h>

#include <panic.h>

#include <debug.h>

#include <bitops.h>

#include <macros.h>

SPINLOCK_INITIALIZE(slab_cache_lock);

static LIST_INITIALIZE(slab_cache_list);

/** Magazine cache */

static slab_cache_t mag_cache;

/** Cache for cache descriptors */

static slab_cache_t slab_cache_cache;

/** Cache for external slab descriptors

 * This time we want per-cpu cache, so do not make it static

 * - using slab for internal slab structures will not deadlock,

 *   as all slab structures are 'small' - control structures of

 *   their caches do not require further allocation

 */

static slab_cache_t *slab_extern_cache;

/** Caches for malloc */

static slab_cache_t *malloc_caches[SLAB_MAX_MALLOC_W - SLAB_MIN_MALLOC_W + 1];

char *malloc_names[] =  {

	"malloc-16",

	"malloc-32",

	"malloc-64",

	"malloc-128",

	"malloc-256",

	"malloc-512",

	"malloc-1K",

	"malloc-2K",

	"malloc-4K",

	"malloc-8K",

	"malloc-16K",

	"malloc-32K",

	"malloc-64K",

	"malloc-128K",

	"malloc-256K"

};

/** Slab descriptor */

typedef struct {

	slab_cache_t *cache; 	/**< Pointer to parent cache. */

	link_t link;       	/**< List of full/partial slabs. */

	void *start;       	/**< Start address of first available item. */

	count_t available; 	/**< Count of available items in this slab. */

	index_t nextavail; 	/**< The index of next available item. */

} slab_t;

#ifdef CONFIG_DEBUG

static int _slab_initialized = 0;

#endif

/**************************************/

/* Slab allocation functions          */

/**

 * Allocate frames for slab space and initialize

 *

 */

static slab_t *slab_space_alloc(slab_cache_t *cache, int flags)

{

	void *data;

	slab_t *slab;

	size_t fsize;

	unsigned int i;

	count_t zone = 0;

	data = frame_alloc_generic(cache->order, FRAME_KA | flags, &zone);

	if (!data) {

		return NULL;

	}

	if (!(cache->flags & SLAB_CACHE_SLINSIDE)) {

		slab = slab_alloc(slab_extern_cache, flags);

		if (!slab) {

			frame_free(KA2PA(data));

			return NULL;

		}

	} else {

		fsize = (PAGE_SIZE << cache->order);

		slab = data + fsize - sizeof(*slab);

	}

	/* Fill in slab structures */

	for (i = 0; i < ((unsigned int) 1 << cache->order); i++)

		frame_set_parent(ADDR2PFN(KA2PA(data)) + i, slab, zone);

	slab->start = data;

	slab->available = cache->objects;

	slab->nextavail = 0;

	slab->cache = cache;

	for (i = 0; i < cache->objects; i++)

		*((int *) (slab->start + i*cache->size)) = i + 1;

	atomic_inc(&cache->allocated_slabs);

	return slab;

}

/**

 * Deallocate space associated with slab

 *

 * @return number of freed frames

 */

static count_t slab_space_free(slab_cache_t *cache, slab_t *slab)

{

	frame_free(KA2PA(slab->start));

	if (! (cache->flags & SLAB_CACHE_SLINSIDE))

		slab_free(slab_extern_cache, slab);

	atomic_dec(&cache->allocated_slabs);

	return 1 << cache->order;

}

/** Map object to slab structure */

static slab_t * obj2slab(void *obj)

{

	return (slab_t *) frame_get_parent(ADDR2PFN(KA2PA(obj)), 0);

}

/**************************************/

/* Slab functions */

/**

 * Return object to slab and call a destructor

 *

 * @param slab If the caller knows directly slab of the object, otherwise NULL

 *

 * @return Number of freed pages

 */

static count_t slab_obj_destroy(slab_cache_t *cache, void *obj, slab_t *slab)

{

	int freed = 0;

	if (!slab)

		slab = obj2slab(obj);

	ASSERT(slab->cache == cache);

	if (cache->destructor)

		freed = cache->destructor(obj);

	spinlock_lock(&cache->slablock);

	ASSERT(slab->available < cache->objects);

	*((int *)obj) = slab->nextavail;

	slab->nextavail = (obj - slab->start) / cache->size;

	slab->available++;

	/* Move it to correct list */

	if (slab->available == cache->objects) {

		/* Free associated memory */

		list_remove(&slab->link);

		spinlock_unlock(&cache->slablock);

		return freed + slab_space_free(cache, slab);

	} else if (slab->available == 1) {

		/* It was in full, move to partial */

		list_remove(&slab->link);

		list_prepend(&slab->link, &cache->partial_slabs);

	}

	spinlock_unlock(&cache->slablock);

	return freed;

}

/**

 * Take new object from slab or create new if needed

 *

 * @return Object address or null

 */

static void *slab_obj_create(slab_cache_t *cache, int flags)

{

	slab_t *slab;

	void *obj;

	spinlock_lock(&cache->slablock);

	if (list_empty(&cache->partial_slabs)) {

		/* Allow recursion and reclaiming

		 * - this should work, as the slab control structures

		 *   are small and do not need to allocate with anything

		 *   other than frame_alloc when they are allocating,

		 *   that's why we should get recursion at most 1-level deep

		 */

		spinlock_unlock(&cache->slablock);

		slab = slab_space_alloc(cache, flags);

		if (!slab)

			return NULL;

		spinlock_lock(&cache->slablock);

	} else {

		slab = list_get_instance(cache->partial_slabs.next, slab_t,

		    link);

		list_remove(&slab->link);

	}

	obj = slab->start + slab->nextavail * cache->size;

	slab->nextavail = *((int *)obj);

	slab->available--;

	if (!slab->available)

		list_prepend(&slab->link, &cache->full_slabs);

	else

		list_prepend(&slab->link, &cache->partial_slabs);

	spinlock_unlock(&cache->slablock);

	if (cache->constructor && cache->constructor(obj, flags)) {

		/* Bad, bad, construction failed */

		slab_obj_destroy(cache, obj, slab);

		return NULL;

	}

	return obj;

}

/**************************************/

/* CPU-Cache slab functions */

/**

 * Finds a full magazine in cache, takes it from list

 * and returns it 

 *

 * @param first If true, return first, else last mag

 */

static slab_magazine_t *get_mag_from_cache(slab_cache_t *cache, int first)

{

	slab_magazine_t *mag = NULL;

	link_t *cur;

	spinlock_lock(&cache->maglock);

	if (!list_empty(&cache->magazines)) {

		if (first)

			cur = cache->magazines.next;

		else

			cur = cache->magazines.prev;

		mag = list_get_instance(cur, slab_magazine_t, link);

		list_remove(&mag->link);

		atomic_dec(&cache->magazine_counter);

	}

	spinlock_unlock(&cache->maglock);

	return mag;

}

/** Prepend magazine to magazine list in cache */

static void put_mag_to_cache(slab_cache_t *cache, slab_magazine_t *mag)

{

	spinlock_lock(&cache->maglock);

	list_prepend(&mag->link, &cache->magazines);

	atomic_inc(&cache->magazine_counter);

	spinlock_unlock(&cache->maglock);

}

/**

 * Free all objects in magazine and free memory associated with magazine

 *

 * @return Number of freed pages

 */

static count_t magazine_destroy(slab_cache_t *cache, slab_magazine_t *mag)

{

	unsigned int i;

	count_t frames = 0;

	for (i = 0; i < mag->busy; i++) {

		frames += slab_obj_destroy(cache, mag->objs[i], NULL);

		atomic_dec(&cache->cached_objs);

	}

	slab_free(&mag_cache, mag);

	return frames;

}

/**

 * Find full magazine, set it as current and return it

 *

 * Assume cpu_magazine lock is held

 */

static slab_magazine_t *get_full_current_mag(slab_cache_t *cache)

{

	slab_magazine_t *cmag, *lastmag, *newmag;

	cmag = cache->mag_cache[CPU->id].current;

	lastmag = cache->mag_cache[CPU->id].last;

	if (cmag) { /* First try local CPU magazines */

		if (cmag->busy)

			return cmag;

		if (lastmag && lastmag->busy) {

			cache->mag_cache[CPU->id].current = lastmag;

			cache->mag_cache[CPU->id].last = cmag;

			return lastmag;

		}

	}

	/* Local magazines are empty, import one from magazine list */

	newmag = get_mag_from_cache(cache, 1);

	if (!newmag)

		return NULL;

	if (lastmag)

		magazine_destroy(cache, lastmag);

	cache->mag_cache[CPU->id].last = cmag;

	cache->mag_cache[CPU->id].current = newmag;

	return newmag;

}

/**

 * Try to find object in CPU-cache magazines

 *

 * @return Pointer to object or NULL if not available

 */

static void *magazine_obj_get(slab_cache_t *cache)

{

	slab_magazine_t *mag;

	void *obj;

	if (!CPU)

		return NULL;

	spinlock_lock(&cache->mag_cache[CPU->id].lock);

	mag = get_full_current_mag(cache);

	if (!mag) {

		spinlock_unlock(&cache->mag_cache[CPU->id].lock);

		return NULL;

	}

	obj = mag->objs[--mag->busy];

	spinlock_unlock(&cache->mag_cache[CPU->id].lock);

	atomic_dec(&cache->cached_objs);

	return obj;

}

/**

 * Assure that the current magazine is empty, return pointer to it, or NULL if 

 * no empty magazine is available and cannot be allocated

 *

 * Assume mag_cache[CPU->id].lock is held

 *

 * We have 2 magazines bound to processor. 

 * First try the current. 

 *  If full, try the last.

 *   If full, put to magazines list.

 *   allocate new, exchange last & current

 *

 */

static slab_magazine_t *make_empty_current_mag(slab_cache_t *cache)

{

	slab_magazine_t *cmag,*lastmag,*newmag;

	cmag = cache->mag_cache[CPU->id].current;

	lastmag = cache->mag_cache[CPU->id].last;

	if (cmag) {

		if (cmag->busy < cmag->size)

			return cmag;

		if (lastmag && lastmag->busy < lastmag->size) {

			cache->mag_cache[CPU->id].last = cmag;

			cache->mag_cache[CPU->id].current = lastmag;

			return lastmag;

		}

	}

	/* current | last are full | nonexistent, allocate new */

	/* We do not want to sleep just because of caching */

	/* Especially we do not want reclaiming to start, as 

	 * this would deadlock */

	newmag = slab_alloc(&mag_cache, FRAME_ATOMIC | FRAME_NO_RECLAIM);

	if (!newmag)

		return NULL;

	newmag->size = SLAB_MAG_SIZE;

	newmag->busy = 0;

	/* Flush last to magazine list */

	if (lastmag)

		put_mag_to_cache(cache, lastmag);

	/* Move current as last, save new as current */

	cache->mag_cache[CPU->id].last = cmag;	

	cache->mag_cache[CPU->id].current = newmag;	

	return newmag;

}

/**

 * Put object into CPU-cache magazine

 *

 * @return 0 - success, -1 - could not get memory

 */

static int magazine_obj_put(slab_cache_t *cache, void *obj)

{

	slab_magazine_t *mag;

	if (!CPU)

		return -1;

	spinlock_lock(&cache->mag_cache[CPU->id].lock);

	mag = make_empty_current_mag(cache);

	if (!mag) {

		spinlock_unlock(&cache->mag_cache[CPU->id].lock);

		return -1;

	}

	mag->objs[mag->busy++] = obj;

	spinlock_unlock(&cache->mag_cache[CPU->id].lock);

	atomic_inc(&cache->cached_objs);

	return 0;

}

/**************************************/

/* Slab cache functions */

/** Return number of objects that fit in certain cache size */

static unsigned int comp_objects(slab_cache_t *cache)

{

	if (cache->flags & SLAB_CACHE_SLINSIDE)

		return ((PAGE_SIZE << cache->order) - sizeof(slab_t)) /

		    cache->size;

	else 

		return (PAGE_SIZE << cache->order) / cache->size;

}

/** Return wasted space in slab */

static unsigned int badness(slab_cache_t *cache)

{

	unsigned int objects;

	unsigned int ssize;

	objects = comp_objects(cache);

	ssize = PAGE_SIZE << cache->order;

	if (cache->flags & SLAB_CACHE_SLINSIDE)

		ssize -= sizeof(slab_t);

	return ssize - objects * cache->size;

}

/**

 * Initialize mag_cache structure in slab cache

 */

static void make_magcache(slab_cache_t *cache)

{

	unsigned int i;

	ASSERT(_slab_initialized >= 2);

	cache->mag_cache = malloc(sizeof(slab_mag_cache_t) * config.cpu_count,

	    0);

	for (i = 0; i < config.cpu_count; i++) {

		memsetb(&cache->mag_cache[i], sizeof(cache->mag_cache[i]), 0);

		spinlock_initialize(&cache->mag_cache[i].lock,

		    "slab_maglock_cpu");

	}

}

/** Initialize allocated memory as a slab cache */

static void

_slab_cache_create(slab_cache_t *cache, char *name, size_t size, size_t align,

    int (*constructor)(void *obj, int kmflag), int (*destructor)(void *obj),

    int flags)

{

	int pages;

	ipl_t ipl;

	memsetb(cache, sizeof(*cache), 0);

	cache->name = name;

	if (align < sizeof(unative_t))

		align = sizeof(unative_t);

	size = ALIGN_UP(size, align);

	cache->size = size;

	cache->constructor = constructor;

	cache->destructor = destructor;

	cache->flags = flags;

	list_initialize(&cache->full_slabs);

	list_initialize(&cache->partial_slabs);

	list_initialize(&cache->magazines);

	spinlock_initialize(&cache->slablock, "slab_lock");

	spinlock_initialize(&cache->maglock, "slab_maglock");

	if (!(cache->flags & SLAB_CACHE_NOMAGAZINE))

		make_magcache(cache);

	/* Compute slab sizes, object counts in slabs etc. */

	if (cache->size < SLAB_INSIDE_SIZE)

		cache->flags |= SLAB_CACHE_SLINSIDE;

	/* Minimum slab order */

	pages = SIZE2FRAMES(cache->size);

	/* We need the 2^order >= pages */

	if (pages == 1)

		cache->order = 0;

	else

		cache->order = fnzb(pages - 1) + 1;

	while (badness(cache) > SLAB_MAX_BADNESS(cache)) {

		cache->order += 1;

	}

	cache->objects = comp_objects(cache);

	/* If info fits in, put it inside */

	if (badness(cache) > sizeof(slab_t))

		cache->flags |= SLAB_CACHE_SLINSIDE;

	/* Add cache to cache list */

	ipl = interrupts_disable();

	spinlock_lock(&slab_cache_lock);

	list_append(&cache->link, &slab_cache_list);

	spinlock_unlock(&slab_cache_lock);

	interrupts_restore(ipl);

}

/** Create slab cache  */

slab_cache_t *

slab_cache_create(char *name, size_t size, size_t align,

    int (*constructor)(void *obj, int kmflag), int (*destructor)(void *obj),

    int flags)

{

	slab_cache_t *cache;

	cache = slab_alloc(&slab_cache_cache, 0);

	_slab_cache_create(cache, name, size, align, constructor, destructor,

	    flags);

	return cache;

}

/** 

 * Reclaim space occupied by objects that are already free

 *

 * @param flags If contains SLAB_RECLAIM_ALL, do aggressive freeing

 * @return Number of freed pages

 */

static count_t _slab_reclaim(slab_cache_t *cache, int flags)

{

	unsigned int i;

	slab_magazine_t *mag;

	count_t frames = 0;

	int magcount;

	if (cache->flags & SLAB_CACHE_NOMAGAZINE)

		return 0; /* Nothing to do */

	/* We count up to original magazine count to avoid

	 * endless loop 

	 */

	magcount = atomic_get(&cache->magazine_counter);

	while (magcount-- && (mag=get_mag_from_cache(cache, 0))) {

		frames += magazine_destroy(cache,mag);

		if (!(flags & SLAB_RECLAIM_ALL) && frames)

			break;

	}

	if (flags & SLAB_RECLAIM_ALL) {

		/* Free cpu-bound magazines */

		/* Destroy CPU magazines */

		for (i = 0; i < config.cpu_count; i++) {

			spinlock_lock(&cache->mag_cache[i].lock);

			mag = cache->mag_cache[i].current;

			if (mag)

				frames += magazine_destroy(cache, mag);

			cache->mag_cache[i].current = NULL;

			mag = cache->mag_cache[i].last;

			if (mag)

				frames += magazine_destroy(cache, mag);

			cache->mag_cache[i].last = NULL;

			spinlock_unlock(&cache->mag_cache[i].lock);

		}

	}

	return frames;

}

/** Check that there are no slabs and remove cache from system  */

void slab_cache_destroy(slab_cache_t *cache)

{

	ipl_t ipl;

	/* First remove cache from link, so that we don't need

	 * to disable interrupts later

	 */

	ipl = interrupts_disable();

	spinlock_lock(&slab_cache_lock);

	list_remove(&cache->link);

	spinlock_unlock(&slab_cache_lock);

	interrupts_restore(ipl);

	/* Do not lock anything, we assume the software is correct and

	 * does not touch the cache when it decides to destroy it */

	/* Destroy all magazines */

	_slab_reclaim(cache, SLAB_RECLAIM_ALL);

	/* All slabs must be empty */

	if (!list_empty(&cache->full_slabs) ||

	    !list_empty(&cache->partial_slabs))

		panic("Destroying cache that is not empty.");

	if (!(cache->flags & SLAB_CACHE_NOMAGAZINE))

		free(cache->mag_cache);

	slab_free(&slab_cache_cache, cache);

}

/** Allocate new object from cache - if no flags given, always returns memory */

void *slab_alloc(slab_cache_t *cache, int flags)

{

	ipl_t ipl;

	void *result = NULL;

	/* Disable interrupts to avoid deadlocks with interrupt handlers */

	ipl = interrupts_disable();

	if (!(cache->flags & SLAB_CACHE_NOMAGAZINE)) {

		result = magazine_obj_get(cache);

	}

	if (!result)

		result = slab_obj_create(cache, flags);

	interrupts_restore(ipl);

	if (result)

		atomic_inc(&cache->allocated_objs);

	return result;

}

/** Return object to cache, use slab if known  */

static void _slab_free(slab_cache_t *cache, void *obj, slab_t *slab)

{

	ipl_t ipl;

	ipl = interrupts_disable();

	if ((cache->flags & SLAB_CACHE_NOMAGAZINE) ||

	    magazine_obj_put(cache, obj)) {

		slab_obj_destroy(cache, obj, slab);

	}

	interrupts_restore(ipl);

	atomic_dec(&cache->allocated_objs);

}

/** Return slab object to cache */

void slab_free(slab_cache_t *cache, void *obj)

{

	_slab_free(cache, obj, NULL);

}

/* Go through all caches and reclaim what is possible */

count_t slab_reclaim(int flags)

{

	slab_cache_t *cache;

	link_t *cur;

	count_t frames = 0;

	spinlock_lock(&slab_cache_lock);

	/* TODO: Add assert, that interrupts are disabled, otherwise

	 * memory allocation from interrupts can deadlock.

	 */

	for (cur = slab_cache_list.next; cur != &slab_cache_list;

	    cur = cur->next) {

		cache = list_get_instance(cur, slab_cache_t, link);

		frames += _slab_reclaim(cache, flags);

	}

	spinlock_unlock(&slab_cache_lock);

	return frames;

}

/* Print list of slabs */

void slab_print_list(void)

{

	int skip = 0;

	printf("slab name        size     pages  obj/pg slabs  cached allocated"

	    " ctl\n");

	printf("---------------- -------- ------ ------ ------ ------ ---------"

	    " ---\n");

	while (true) {

		slab_cache_t *cache;

		link_t *cur;

		ipl_t ipl;

		int i;

		/*

		 * We must not hold the slab_cache_lock spinlock when printing

		 * the statistics. Otherwise we can easily deadlock if the print

		 * needs to allocate memory.

		 *

		 * Therefore, we walk through the slab cache list, skipping some

		 * amount of already processed caches during each iteration and

		 * gathering statistics about the first unprocessed cache. For

		 * the sake of printing the statistics, we realese the

		 * slab_cache_lock and reacquire it afterwards. Then the walk

		 * starts again.

		 *

		 * This limits both the efficiency and also accuracy of the

		 * obtained statistics. The efficiency is decreased because the

		 * time complexity of the algorithm is quadratic instead of

		 * linear. The accuracy is impacted because we drop the lock

		 * after processing one cache. If there is someone else

		 * manipulating the cache list, we might omit an arbitrary

		 * number of caches or process one cache multiple times.

		 * However, we don't bleed for this algorithm for it is only

		 * statistics.

		 */

		ipl = interrupts_disable();

		spinlock_lock(&slab_cache_lock);

		for (i = 0, cur = slab_cache_list.next;

		    i < skip && cur != &slab_cache_list;

		    i++, cur = cur->next)

			;

		if (cur == &slab_cache_list) {

			spinlock_unlock(&slab_cache_lock);

			interrupts_restore(ipl);

			break;

		}

		skip++;

		cache = list_get_instance(cur, slab_cache_t, link);

		char *name = cache->name;

		uint8_t order = cache->order;

		size_t size = cache->size;

		unsigned int objects = cache->objects;

		long allocated_slabs = atomic_get(&cache->allocated_slabs);

		long cached_objs = atomic_get(&cache->cached_objs);

		long allocated_objs = atomic_get(&cache->allocated_objs);

		int flags = cache->flags;

		spinlock_unlock(&slab_cache_lock);

		interrupts_restore(ipl);

		printf("%-16s %8" PRIs " %6d %6u %6ld %6ld %9ld %-3s\n",

		    name, size, (1 << order), objects, allocated_slabs,

		    cached_objs, allocated_objs,

		    flags & SLAB_CACHE_SLINSIDE ? "in" : "out");

	}

}

void slab_cache_init(void)

{

	int i, size;

	/* Initialize magazine cache */

	_slab_cache_create(&mag_cache, "slab_magazine",

	    sizeof(slab_magazine_t) + SLAB_MAG_SIZE * sizeof(void*),

	    sizeof(uintptr_t), NULL, NULL, SLAB_CACHE_NOMAGAZINE |

	    SLAB_CACHE_SLINSIDE);

	/* Initialize slab_cache cache */

	_slab_cache_create(&slab_cache_cache, "slab_cache",

	    sizeof(slab_cache_cache), sizeof(uintptr_t), NULL, NULL,

	    SLAB_CACHE_NOMAGAZINE | SLAB_CACHE_SLINSIDE);

	/* Initialize external slab cache */

	slab_extern_cache = slab_cache_create("slab_extern", sizeof(slab_t), 0,

	    NULL, NULL, SLAB_CACHE_SLINSIDE | SLAB_CACHE_MAGDEFERRED);

	/* Initialize structures for malloc */

	for (i = 0, size = (1 << SLAB_MIN_MALLOC_W);

	    i < (SLAB_MAX_MALLOC_W - SLAB_MIN_MALLOC_W + 1);

	    i++, size <<= 1) {

		malloc_caches[i] = slab_cache_create(malloc_names[i], size, 0,

		    NULL, NULL, SLAB_CACHE_MAGDEFERRED);

	}

#ifdef CONFIG_DEBUG       

	_slab_initialized = 1;

#endif

}

/** Enable cpu_cache

 *

 * Kernel calls this function, when it knows the real number of

 * processors. 

 * Allocate slab for cpucache and enable it on all existing

 * slabs that are SLAB_CACHE_MAGDEFERRED

 */

void slab_enable_cpucache(void)

{

	link_t *cur;

	slab_cache_t *s;

#ifdef CONFIG_DEBUG

	_slab_initialized = 2;

#endif

	spinlock_lock(&slab_cache_lock);

	for (cur = slab_cache_list.next; cur != &slab_cache_list;

	    cur = cur->next){

		s = list_get_instance(cur, slab_cache_t, link);

		if ((s->flags & SLAB_CACHE_MAGDEFERRED) !=

		    SLAB_CACHE_MAGDEFERRED)

			continue;

		make_magcache(s);

		s->flags &= ~SLAB_CACHE_MAGDEFERRED;

	}

	spinlock_unlock(&slab_cache_lock);

}

/**************************************/

/* kalloc/kfree functions             */

void *malloc(unsigned int size, int flags)

{

	ASSERT(_slab_initialized);

	ASSERT(size && size <= (1 << SLAB_MAX_MALLOC_W));

	if (size < (1 << SLAB_MIN_MALLOC_W))

		size = (1 << SLAB_MIN_MALLOC_W);

	int idx = fnzb(size - 1) - SLAB_MIN_MALLOC_W + 1;

	return slab_alloc(malloc_caches[idx], flags);

}

void *realloc(void *ptr, unsigned int size, int flags)

{

	ASSERT(_slab_initialized);

	ASSERT(size <= (1 << SLAB_MAX_MALLOC_W));

	void *new_ptr;

	if (size > 0) {

		if (size < (1 << SLAB_MIN_MALLOC_W))

			size = (1 << SLAB_MIN_MALLOC_W);

		int idx = fnzb(size - 1) - SLAB_MIN_MALLOC_W + 1;

		new_ptr = slab_alloc(malloc_caches[idx], flags);

	} else

		new_ptr = NULL;

	if ((new_ptr != NULL) && (ptr != NULL)) {

		slab_t *slab = obj2slab(ptr);

		memcpy(new_ptr, ptr, min(size, slab->cache->size));

	}

	if (ptr != NULL)

		free(ptr);

	return new_ptr;

}

void free(void *ptr)

{

	if (!ptr)

		return;

	slab_t *slab = obj2slab(ptr);

	_slab_free(slab->cache, ptr, slab);

}

/** @}

 */