From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx> Subject: mm: slab: provide krealloc_array() 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. Link: https://lkml.kernel.org/r/20201109110654.12547-3-brgl@xxxxxxxx Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Christian Knig <christian.koenig@xxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: David Airlie <airlied@xxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Gustavo Padovan <gustavo@xxxxxxxxxxx> Cc: James Morse <james.morse@xxxxxxx> Cc: Jaroslav Kysela <perex@xxxxxxxx> Cc: Jason Wang <jasowang@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> Cc: Maxime Ripard <mripard@xxxxxxxxxx> Cc: "Michael S . Tsirkin" <mst@xxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Robert Richter <rric@xxxxxxxxxx> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx> Cc: Takashi Iwai <tiwai@xxxxxxxx> Cc: Takashi Iwai <tiwai@xxxxxxx> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> Cc: Tony Luck <tony.luck@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/core-api/memory-allocation.rst | 4 +++ include/linux/slab.h | 18 +++++++++++++++++ 2 files changed, 22 insertions(+) --- a/Documentation/core-api/memory-allocation.rst~mm-slab-provide-krealloc_array +++ a/Documentation/core-api/memory-allocation.rst @@ -147,6 +147,10 @@ The address of a chunk allocated with `k 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 resizing 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. --- a/include/linux/slab.h~mm-slab-provide-krealloc_array +++ a/include/linux/slab.h @@ -593,6 +593,24 @@ static inline void *kmalloc_array(size_t } /** + * 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. * @size: element size. _
