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Commit fd76bab2 authored by Pekka Enberg's avatar Pekka Enberg Committed by Linus Torvalds
Browse files

slab: introduce krealloc 



This introduce krealloc() that reallocates memory while keeping the contents
unchanged.  The allocator avoids reallocation if the new size fits the
currently used cache.  I also added a simple non-optimized version for
mm/slob.c for compatibility.

[akpm@linux-foundation.org: fix warnings]
Acked-by: default avatarJosef Sipek <jsipek@fsl.cs.sunysb.edu>
Acked-by: default avatarMatt Mackall <mpm@selenic.com>
Acked-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e3ebadd9

include/linux/slab.h

+2 −1
Original line number Diff line number Diff line
@@ -72,8 +72,9 @@ static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep, 
 */

void *__kmalloc(size_t, gfp_t);

void *__kzalloc(size_t, gfp_t);

void * __must_check krealloc(const void *, size_t, gfp_t);

void kfree(const void *);

unsigned int ksize(const void *);

size_t ksize(const void *);



/**

 * kcalloc - allocate memory for an array. The memory is set to zero.

mm/slab.c

+48 −1
Original line number Diff line number Diff line
@@ -3739,6 +3739,53 @@ void *__kmalloc(size_t size, gfp_t flags) 
EXPORT_SYMBOL(__kmalloc);

#endif



/**

 * krealloc - reallocate memory. The contents will remain unchanged.

 *

 * @p: object to reallocate memory for.

 * @new_size: how many bytes of memory are required.

 * @flags: the type of memory to allocate.

 *

 * The contents of the object pointed to are preserved up to the

 * lesser of the new and old sizes.  If @p is %NULL, krealloc()

 * behaves exactly like kmalloc().  If @size is 0 and @p is not a

 * %NULL pointer, the object pointed to is freed.

 */

void *krealloc(const void *p, size_t new_size, gfp_t flags)

{

	struct kmem_cache *cache, *new_cache;

	void *ret;



	if (unlikely(!p))

		return kmalloc_track_caller(new_size, flags);



	if (unlikely(!new_size)) {

		kfree(p);

		return NULL;

	}



	cache = virt_to_cache(p);

	new_cache = __find_general_cachep(new_size, flags);



	/*

 	 * If new size fits in the current cache, bail out.

 	 */

	if (likely(cache == new_cache))

		return (void *)p;



	/*

 	 * We are on the slow-path here so do not use __cache_alloc

 	 * because it bloats kernel text.

 	 */

	ret = kmalloc_track_caller(new_size, flags);

	if (ret) {

		memcpy(ret, p, min(new_size, ksize(p)));

		kfree(p);

	}

	return ret;

}

EXPORT_SYMBOL(krealloc);



/**

 * kmem_cache_free - Deallocate an object

 * @cachep: The cache the allocation was from.
@@ -4481,7 +4528,7 @@ const struct seq_operations slabstats_op = { 
 * allocated with either kmalloc() or kmem_cache_alloc(). The object

 * must not be freed during the duration of the call.

 */

unsigned int ksize(const void *objp)

size_t ksize(const void *objp)

{

	if (unlikely(objp == NULL))

		return 0;

mm/slob.c

+34 −1
Original line number Diff line number Diff line
@@ -190,6 +190,39 @@ void *__kmalloc(size_t size, gfp_t gfp) 
}

EXPORT_SYMBOL(__kmalloc);



/**

 * krealloc - reallocate memory. The contents will remain unchanged.

 *

 * @p: object to reallocate memory for.

 * @new_size: how many bytes of memory are required.

 * @flags: the type of memory to allocate.

 *

 * The contents of the object pointed to are preserved up to the

 * lesser of the new and old sizes.  If @p is %NULL, krealloc()

 * behaves exactly like kmalloc().  If @size is 0 and @p is not a

 * %NULL pointer, the object pointed to is freed.

 */

void *krealloc(const void *p, size_t new_size, gfp_t flags)

{

	void *ret;



	if (unlikely(!p))

		return kmalloc_track_caller(new_size, flags);



	if (unlikely(!new_size)) {

		kfree(p);

		return NULL;

	}



	ret = kmalloc_track_caller(new_size, flags);

	if (ret) {

		memcpy(ret, p, min(new_size, ksize(p)));

		kfree(p);

	}

	return ret;

}

EXPORT_SYMBOL(krealloc);



void kfree(const void *block)

{

	bigblock_t *bb, **last = &bigblocks;
@@ -219,7 +252,7 @@ void kfree(const void *block) 


EXPORT_SYMBOL(kfree);



unsigned int ksize(const void *block)

size_t ksize(const void *block)

{

	bigblock_t *bb;

	unsigned long flags;