On Wed, 29 Jul 2020, Qianli Zhao wrote: > From: Qianli Zhao <zhaoqianli@xxxxxxxxxx> > > 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 > > Signed-off-by: Qianli Zhao <zhaoqianli@xxxxxxxxxx> > --- > mm/slab.h | 2 +- > mm/slab_common.c | 7 ++----- > 2 files changed, 3 insertions(+), 6 deletions(-) > > diff --git a/mm/slab.h b/mm/slab.h > index 74f7e09..c12fb65 100644 > --- a/mm/slab.h > +++ b/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[]; > }; > > /* This is removed in the -mm tree, see https://www.ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-slab-use-a-single-set-of-kmem_caches-for-all-allocations.patch > diff --git a/mm/slab_common.c b/mm/slab_common.c > index fe8b684..56f4818 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -166,9 +166,7 @@ static int init_memcg_params(struct kmem_cache *s, > 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; > > @@ -199,8 +197,7 @@ static int update_memcg_params(struct kmem_cache *s, int new_array_size) > { > 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; > > -- > 2.7.4 > >
