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.
[[email protected]: fix warnings]
Acked-by: Josef Sipek <[email protected]>
Acked-by: Matt Mackall <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Signed-off-by: Pekka Enberg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 1ef822e..2f8f60f 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -72,8 +72,9 @@
*/
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.
diff --git a/mm/slab.c b/mm/slab.c
index 168bfe9..8b71a9c 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3740,6 +3740,53 @@
#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.
@@ -4481,7 +4528,7 @@
* 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;
diff --git a/mm/slob.c b/mm/slob.c
index 5adc29c..03cce3d 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -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;
@@ -219,7 +252,7 @@
EXPORT_SYMBOL(kfree);
-unsigned int ksize(const void *block)
+size_t ksize(const void *block)
{
bigblock_t *bb;
unsigned long flags;
