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/*
* \brief Kmem_cache implementation
* \author Christian Helmuth
* \date 2007-01-22
*
* In Linux 2.6 this resides in mm/slab.c.
*
* I'll disregard the following function currently...
*
* extern struct kmem_cache *kmem_find_general_cachep(size_t size, gfp_t gfpflags);
* extern void *kmem_cache_zalloc(struct kmem_cache *, gfp_t);
*/
/* Linux */
#include <linux/slab.h>
#include "local.h"
/*******************
** Configuration **
*******************/
#define DEBUG_SLAB 0
#if DEBUG_SLAB
# define DEBUG_SLAB_ALLOC 1
#else
# define DEBUG_SLAB_ALLOC 0
#endif
/*
* Kmem cache structure
*/
struct kmem_cache
{
const char *name; /**< cache name */
unsigned size; /**< obj size */
struct ddekit_slab *ddekit_slab_cache; /**< backing DDEKit cache */
ddekit_lock_t cache_lock; /**< lock */
void (*ctor)(void *); /**< object constructor */
};
/**
* Return size of objects in cache
*/
unsigned int kmem_cache_size(struct kmem_cache *cache)
{
return cache->size;
}
/**
* Return name of cache
*/
const char *kmem_cache_name(struct kmem_cache *cache)
{
return cache->name;
}
/**
* kmem_cache_shrink - Shrink a cache.
* @cachep: The cache to shrink.
*
* Releases as many slabs as possible for a cache.
* To help debugging, a zero exit status indicates all slabs were released.
*/
int kmem_cache_shrink(struct kmem_cache *cache)
{
/* noop */
return 1;
}
/**
* kmem_cache_free - Deallocate an object
* @cachep: The cache the allocation was from.
* @objp: The previously allocated object.
*
* Free an object which was previously allocated from this
* cache.
*/
void kmem_cache_free(struct kmem_cache *cache, void *objp)
{
ddekit_log(DEBUG_SLAB_ALLOC, "\"%s\" (%p)", cache->name, objp);
ddekit_lock_lock(&cache->cache_lock);
ddekit_slab_free(cache->ddekit_slab_cache, objp);
ddekit_lock_unlock(&cache->cache_lock);
}
/**
* kmem_cache_alloc - Allocate an object
* @cachep: The cache to allocate from.
* @flags: See kmalloc().
*
* Allocate an object from this cache. The flags are only relevant
* if the cache has no available objects.
*/
void *kmem_cache_alloc(struct kmem_cache *cache, gfp_t flags)
{
void *ret;
ddekit_log(DEBUG_SLAB_ALLOC, "\"%s\" flags=%x", cache->name, flags);
ddekit_lock_lock(&cache->cache_lock);
ret = ddekit_slab_alloc(cache->ddekit_slab_cache);
ddekit_lock_unlock(&cache->cache_lock);
// XXX: is it valid to run ctor AND memset to zero?
if (flags & __GFP_ZERO)
memset(ret, 0, cache->size);
else if (cache->ctor)
cache->ctor(ret);
return ret;
}
/**
* kmem_cache_destroy - delete a cache
* @cachep: the cache to destroy
*
* Remove a struct kmem_cache object from the slab cache.
* Returns 0 on success.
*
* It is expected this function will be called by a module when it is
* unloaded. This will remove the cache completely, and avoid a duplicate
* cache being allocated each time a module is loaded and unloaded, if the
* module doesn't have persistent in-kernel storage across loads and unloads.
*
* The cache must be empty before calling this function.
*
* The caller must guarantee that noone will allocate memory from the cache
* during the kmem_cache_destroy().
*/
void kmem_cache_destroy(struct kmem_cache *cache)
{
ddekit_log(DEBUG_SLAB, "\"%s\"", cache->name);
ddekit_slab_destroy(cache->ddekit_slab_cache);
ddekit_simple_free(cache);
}
/**
* kmem_cache_create - Create a cache.
* @name: A string which is used in /proc/slabinfo to identify this cache.
* @size: The size of objects to be created in this cache.
* @align: The required alignment for the objects.
* @flags: SLAB flags
* @ctor: A constructor for the objects.
*
* Returns a ptr to the cache on success, NULL on failure.
* Cannot be called within a int, but can be interrupted.
* The @ctor is run when new pages are allocated by the cache
* and the @dtor is run before the pages are handed back.
*
* @name must be valid until the cache is destroyed. This implies that
* the module calling this has to destroy the cache before getting unloaded.
*
* The flags are
*
* %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
* to catch references to uninitialised memory.
*
* %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
* for buffer overruns.
*
* %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
* cacheline. This can be beneficial if you're counting cycles as closely
* as davem.
*/
struct kmem_cache * kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags,
void (*ctor)(void *))
{
ddekit_log(DEBUG_SLAB, "\"%s\" obj_size=%d", name, size);
struct kmem_cache *cache;
if (!name) {
printk("kmem_cache name reqeuired\n");
return 0;
}
cache = ddekit_simple_malloc(sizeof(*cache));
if (!cache) {
printk("No memory for slab cache\n");
return 0;
}
/* Initialize a physically contiguous cache for kmem */
if (!(cache->ddekit_slab_cache = ddekit_slab_init(size, 1))) {
printk("DDEKit slab init failed\n");
ddekit_simple_free(cache);
return 0;
}
cache->name = name;
cache->size = size;
cache->ctor = ctor;
ddekit_lock_init_unlocked(&cache->cache_lock);
return cache;
}
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