The patch titled
Subject: mm: slab: avoid the use of one-element array and use struct_size() helper
has been added to the -mm tree. Its filename is
mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch
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------------------------------------------------------
From: Qianli Zhao <zhaoqianli@xxxxxxxxxx>
Subject: mm: slab: avoid the use of one-element array and use struct_size() helper
There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The
older style of one-element or zero-length arrays should no longer be
used[2].
Make use of the struct_size() helper instead of an open-coded version in
order to avoid any potential type mistakes.
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Link: http://lkml.kernel.org/r/1596034214-15010-1-git-send-email-zhaoqianligood@xxxxxxxxx
Signed-off-by: Qianli Zhao <zhaoqianli@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab.h | 2 +-
mm/slab_common.c | 7 ++-----
2 files changed, 3 insertions(+), 6 deletions(-)
--- a/mm/slab_common.c~mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper
+++ a/mm/slab_common.c
@@ -168,9 +168,7 @@ static int init_memcg_params(struct kmem
if (!memcg_nr_cache_ids)
return 0;
- arr = kvzalloc(sizeof(struct memcg_cache_array) +
- memcg_nr_cache_ids * sizeof(void *),
- GFP_KERNEL);
+ arr = kvzalloc(struct_size(arr, entries, memcg_nr_cache_ids), GFP_KERNEL);
if (!arr)
return -ENOMEM;
@@ -201,8 +199,7 @@ static int update_memcg_params(struct km
{
struct memcg_cache_array *old, *new;
- new = kvzalloc(sizeof(struct memcg_cache_array) +
- new_array_size * sizeof(void *), GFP_KERNEL);
+ new = kvzalloc(struct_size(new, entries, new_array_size), GFP_KERNEL);
if (!new)
return -ENOMEM;
--- a/mm/slab.h~mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper
+++ a/mm/slab.h
@@ -34,7 +34,7 @@ struct kmem_cache {
struct memcg_cache_array {
struct rcu_head rcu;
- struct kmem_cache *entries[0];
+ struct kmem_cache *entries[];
};
/*
_
Patches currently in -mm which might be from zhaoqianli@xxxxxxxxxx are
mm-slab-avoid-the-use-of-one-element-array-and-use-struct_size-helper.patch
