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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.

 */

#include <synch/spinlock.h>

#include <mm/slab.h>

#include <list.h>

#include <memstr.h>

#include <align.h>

#include <mm/heap.h>

#include <config.h>

#include <print.h>

#include <arch.h>

#include <panic.h>

SPINLOCK_INITIALIZE(slab_cache_lock);

LIST_INITIALIZE(slab_cache_list);

slab_cache_t mag_cache;

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

/* SLAB low level functions */

/**

 * Return object to slab and call a destructor

 *

 * @return Number of freed pages

 */

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

{

	return 0;

}

/**

 * 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)

{

	return NULL;

}

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

/* CPU-Cache slab functions */

/**

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

 *

 * Assume cpu->lock is locked 

 *

 * @return Number of freed pages

 */

static count_t magazine_destroy(slab_cache_t *cache, 

				slab_magazine_t *mag)

{

	int i;

	count_t frames = 0;

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

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

	slab_free(&mag_cache, mag);

	return frames;

}

/**

 * 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;

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

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

	if (!mag)

		goto out;

	if (!mag->busy) {

		/* If current is empty && last exists && not empty, exchange */

		if (cache->mag_cache[CPU->id].last \

		    && cache->mag_cache[CPU->id].last->busy) {

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

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

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

			goto gotit;

		}

		/* If still not busy, exchange current with some frome

		 * other full magazines */

		spinlock_lock(&cache->lock);

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

			spinlock_unlock(&cache->lock);

			goto out;

		}

		/* Free current magazine and take one from list */

		slab_free(&mag_cache, mag);

		mag = list_get_instance(cache->magazines.next,

					slab_magazine_t,

					link);

		list_remove(&mag->link);

		spinlock_unlock(&cache->lock);

	}

gotit:

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

	return mag->objs[--mag->busy];

out:	

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

	return NULL;

}

/**

 * Put object into CPU-cache magazine

 *

 * 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

 *

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

 */

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

{

	slab_magazine_t *mag;

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

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

	if (!mag) {

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

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

		 * this would deadlock */

		mag = slab_alloc(&mag_cache, SLAB_ATOMIC | SLAB_NO_RECLAIM);

		if (!mag) /* Allocation failed, give up on caching */

			goto errout;

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

		mag->size = SLAB_MAG_SIZE;

		mag->busy = 0;

	} else if (mag->busy == mag->size) {

		/* If the last is full | empty, allocate new */

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

		if (!mag || mag->size == mag->busy) {

			if (mag) 

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

			mag = slab_alloc(&mag_cache, SLAB_ATOMIC | SLAB_NO_RECLAIM);

			if (!mag)

				goto errout;

			mag->size = SLAB_MAG_SIZE;

			mag->busy = 0;

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

		} 

		/* Exchange the 2 */

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

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

	}

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

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

	return 0;

errout:

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

	return -1;

}

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

/* Top level SLAB functions */

/** 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),

		   void (*destructor)(void *obj),

		   int flags)

{

	int i;

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

	cache->name = name;

	cache->align = align;

	cache->size = ALIGN_UP(size, align);

	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->lock, "cachelock");

	if (! cache->flags & SLAB_CACHE_NOMAGAZINE) {

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

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

					    "cpucachelock");

	}

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

	if (cache->size < SLAB_INSIDE_SIZE)

		cache->flags |= SLAB_CACHE_SLINSIDE;

	spinlock_lock(&slab_cache_lock);

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

	spinlock_unlock(&slab_cache_lock);

}

/** Create slab cache  */

slab_cache_t * slab_cache_create(char *name,

				 size_t size,

				 size_t align,

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

				 void (*destructor)(void *obj),

				 int flags)

{

	slab_cache_t *cache;

	cache = malloc(sizeof(*cache) + config.cpu_count*sizeof(cache->mag_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)

{

	int i;

	slab_magazine_t *mag;

	link_t *cur;

	count_t frames = 0;

	if (cache->flags & SLAB_CACHE_NOMAGAZINE)

		return 0; /* Nothing to do */

	/* First lock all cpu caches, then the complete cache lock */

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

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

	spinlock_lock(&cache->lock);

	if (flags & SLAB_RECLAIM_ALL) {

		/* Destroy CPU magazines */

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

			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;

		}

		/* Destroy full magazines */

		cur=cache->magazines.next;

		while (cur!=&cache->magazines) {

			mag = list_get_instance(cur, slab_magazine_t, link);

			cur = cur->next;

			list_remove(cur->prev);

			frames += magazine_destroy(cache,mag);

		}

	}

	spinlock_unlock(&cache->lock);

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

		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)

{

	/* 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.");

	spinlock_lock(&slab_cache_lock);

	list_remove(&cache->link);

	spinlock_unlock(&slab_cache_lock);

	free(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);

	return result;

}

/** Return object to cache  */

void slab_free(slab_cache_t *cache, void *obj)

{

	ipl_t ipl;

	ipl = interrupts_disable();

	if (cache->flags & SLAB_CACHE_NOMAGAZINE)

		slab_obj_destroy(cache, obj);

	else {

		if (magazine_obj_put(cache, obj)) /* If magazine put failed */

			slab_obj_destroy(cache, obj);

	}

	interrupts_restore(ipl);

}

/* 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);

	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)

{

	slab_cache_t *cache;

	link_t *cur;

	spinlock_lock(&slab_cache_lock);

	printf("SLAB name\tObj size\n");

	for (cur = slab_cache_list.next;cur!=&slab_cache_list; cur=cur->next) {

		cache = list_get_instance(cur, slab_cache_t, link);

		printf("%s\t%d\n", cache->name, cache->size);

	}

	spinlock_unlock(&slab_cache_lock);

}

void slab_cache_init(void)

{

	/* Initialize magazine cache */

	_slab_cache_create(&mag_cache,

			   "slab_magazine",

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

			   sizeof(__address),

			   NULL, NULL,

			   SLAB_CACHE_NOMAGAZINE);

	/* Initialize structures for malloc */

}