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Date: Thu, 22 Feb 2007 14:40:22 +0200 (EET)
From: Pekka J Enberg <penberg@...helsinki.fi>
To: akpm@...ux-foundation.org
cc: linux-kernel@...r.kernel.org, mpm@...enic.com, clameter@....com,
jsipek@....cs.sunysb.edu
Subject: [PATCH 1/2] slab: introduce krealloc
From: Pekka Enberg <penberg@...helsinki.fi>
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.
Cc: Josef Sipek <jsipek@....cs.sunysb.edu>
Cc: Matt Mackall <mpm@...enic.com>
Cc: Christoph Lameter <clameter@....com>
Signed-off-by: Pekka Enberg <penberg@...helsinki.fi>
---
include/linux/slab.h | 1 +
mm/slab.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
mm/slob.c | 33 +++++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+)
Index: 2.6/include/linux/slab.h
===================================================================
--- 2.6.orig/include/linux/slab.h 2007-02-22 11:33:15.000000000 +0200
+++ 2.6/include/linux/slab.h 2007-02-22 11:33:39.000000000 +0200
@@ -72,6 +72,7 @@
*/
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 *);
Index: 2.6/mm/slab.c
===================================================================
--- 2.6.orig/mm/slab.c 2007-02-22 11:33:15.000000000 +0200
+++ 2.6/mm/slab.c 2007-02-22 11:33:28.000000000 +0200
@@ -3737,6 +3737,53 @@
#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.
* @objp: The previously allocated object.
Index: 2.6/mm/slob.c
===================================================================
--- 2.6.orig/mm/slob.c 2007-02-22 11:33:15.000000000 +0200
+++ 2.6/mm/slob.c 2007-02-22 11:33:28.000000000 +0200
@@ -190,6 +190,39 @@
}
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;
-
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