mbox series

[v2,0/8] slab: provide and use krealloc_array()

Message ID 20201102152037.963-1-brgl@bgdev.pl
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Series slab: provide and use krealloc_array() | expand

Message

Bartosz Golaszewski Nov. 2, 2020, 3:20 p.m. UTC
From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Andy brought to my attention the fact that users allocating an array of
equally sized elements should check if the size multiplication doesn't
overflow. This is why we have helpers like kmalloc_array().

However we don't have krealloc_array() equivalent and there are many
users who do their own multiplication when calling krealloc() for arrays.

This series provides krealloc_array() and uses it in a couple places.

A separate series will follow adding devm_krealloc_array() which is
needed in the xilinx adc driver.

v1 -> v2:
- added a kernel doc for krealloc_array()
- mentioned krealloc et al in the docs
- collected review tags

Bartosz Golaszewski (8):
  mm: slab: provide krealloc_array()
  ALSA: pcm: use krealloc_array()
  vhost: vringh: use krealloc_array()
  pinctrl: use krealloc_array()
  edac: ghes: use krealloc_array()
  drm: atomic: use krealloc_array()
  hwtracing: intel: use krealloc_array()
  dma-buf: use krealloc_array()

 Documentation/core-api/memory-allocation.rst |  4 ++++
 drivers/dma-buf/sync_file.c                  |  4 ++--
 drivers/edac/ghes_edac.c                     |  4 ++--
 drivers/gpu/drm/drm_atomic.c                 |  3 ++-
 drivers/hwtracing/intel_th/msu.c             |  2 +-
 drivers/pinctrl/pinctrl-utils.c              |  2 +-
 drivers/vhost/vringh.c                       |  3 ++-
 include/linux/slab.h                         | 18 ++++++++++++++++++
 sound/core/pcm_lib.c                         |  4 ++--
 9 files changed, 34 insertions(+), 10 deletions(-)

Comments

Bartosz Golaszewski Nov. 3, 2020, 10:12 a.m. UTC | #1
On Tue, Nov 3, 2020 at 5:14 AM Joe Perches <joe@perches.com> wrote:
>

> On Mon, 2020-11-02 at 16:20 +0100, Bartosz Golaszewski wrote:

> > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

> >

> > Andy brought to my attention the fact that users allocating an array of

> > equally sized elements should check if the size multiplication doesn't

> > overflow. This is why we have helpers like kmalloc_array().

> >

> > However we don't have krealloc_array() equivalent and there are many

> > users who do their own multiplication when calling krealloc() for arrays.

> >

> > This series provides krealloc_array() and uses it in a couple places.

>

> My concern about this is a possible assumption that __GFP_ZERO will

> work, and as far as I know, it will not.

>


Yeah so I had this concern for devm_krealloc() and even sent a patch
that extended it to honor __GFP_ZERO before I noticed that regular
krealloc() silently ignores __GFP_ZERO. I'm not sure if this is on
purpose. Maybe we should either make krealloc() honor __GFP_ZERO or
explicitly state in its documentation that it ignores it?

This concern isn't really related to this patch as such - it's more of
a general krealloc() inconsistency.

Bartosz