From: Bartosz Golaszewski bgolaszewski@baylibre.com
When allocating an array of elements, users should check for multiplication overflow or preferably use one of the provided helpers like: kmalloc_array().
There's no krealloc_array() counterpart but there are many users who use regular krealloc() to reallocate arrays. Let's provide an actual krealloc_array() implementation.
While at it: add some documentation regarding krealloc.
Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com Acked-by: Vlastimil Babka vbabka@suse.cz --- Documentation/core-api/memory-allocation.rst | 4 ++++ include/linux/slab.h | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+)
diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst index 4446a1ac36cc..6dc38b40439a 100644 --- a/Documentation/core-api/memory-allocation.rst +++ b/Documentation/core-api/memory-allocation.rst @@ -147,6 +147,10 @@ The address of a chunk allocated with `kmalloc` is aligned to at least ARCH_KMALLOC_MINALIGN bytes. For sizes which are a power of two, the alignment is also guaranteed to be at least the respective size.
+Chunks allocated with `kmalloc` can be resized with `krealloc`. Similarly +to `kmalloc_array`: a helper for resising arrays is provided in the form of +`krealloc_array`. + For large allocations you can use vmalloc() and vzalloc(), or directly request pages from the page allocator. The memory allocated by `vmalloc` and related functions is not physically contiguous. diff --git a/include/linux/slab.h b/include/linux/slab.h index dd6897f62010..be4ba5867ac5 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -592,6 +592,24 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags) return __kmalloc(bytes, flags); }
+/** + * krealloc_array - reallocate memory for an array. + * @p: pointer to the memory chunk to reallocate + * @new_n: new number of elements to alloc + * @new_size: new size of a single member of the array + * @flags: the type of memory to allocate (see kmalloc) + */ +static __must_check inline void * +krealloc_array(void *p, size_t new_n, size_t new_size, gfp_t flags) +{ + size_t bytes; + + if (unlikely(check_mul_overflow(new_n, new_size, &bytes))) + return NULL; + + return krealloc(p, bytes, flags); +} + /** * kcalloc - allocate memory for an array. The memory is set to zero. * @n: number of elements.