On Fri, Jul 29, 2022 at 03:23:06PM +0000, Yafang Shao wrote:
> Currently bpf_map_area_alloc() is used to allocate a container of struct
> bpf_map or members in this container. To distinguish the map creation
> and other members, let split it into two different helpers,
> - bpf_map_container_alloc()
> Used to allocate a container of struct bpf_map, the container is as
> follows,
> struct bpf_map_container {
> struct bpf_map map; // the map must be the first member
> ....
> };
> Pls. note that the struct bpf_map_contianer is a abstract one, which
> can be struct bpf_array, struct bpf_bloom_filter and etc.
>
> In this helper, it will call bpf_map_save_memcg() to init memcg
> relevant data in the bpf map. And these data will be cleared in
> bpf_map_container_free().
>
> - bpf_map_area_alloc()
> Now it is used to allocate the members in a contianer only.
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> ---
> include/linux/bpf.h | 4 ++++
> kernel/bpf/syscall.c | 56 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 60 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 20c26aed7896..2d971b0eb24b 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1634,9 +1634,13 @@ void bpf_map_inc_with_uref(struct bpf_map *map);
> struct bpf_map * __must_check bpf_map_inc_not_zero(struct bpf_map *map);
> void bpf_map_put_with_uref(struct bpf_map *map);
> void bpf_map_put(struct bpf_map *map);
> +void *bpf_map_container_alloc(u64 size, int numa_node);
> +void *bpf_map_container_mmapable_alloc(u64 size, int numa_node,
> + u32 align, u32 offset);
> void *bpf_map_area_alloc(u64 size, int numa_node);
> void *bpf_map_area_mmapable_alloc(u64 size, int numa_node);
> void bpf_map_area_free(void *base);
> +void bpf_map_container_free(void *base);
> bool bpf_map_write_active(const struct bpf_map *map);
> void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);
> int generic_map_lookup_batch(struct bpf_map *map,
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 83c7136c5788..1a1a81a11b37 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -495,6 +495,62 @@ static void bpf_map_release_memcg(struct bpf_map *map)
> }
> #endif
>
> +/*
> + * The return pointer is a bpf_map container, as follow,
> + * struct bpf_map_container {
> + * struct bpf_map map;
> + * ...
> + * };
> + *
> + * It is used in map creation path.
> + */
> +void *bpf_map_container_alloc(u64 size, int numa_node)
> +{
> + struct bpf_map *map;
> + void *container;
> +
> + container = __bpf_map_area_alloc(size, numa_node, false);
> + if (!container)
> + return NULL;
> +
> + map = (struct bpf_map *)container;
> + bpf_map_save_memcg(map);
> +
> + return container;
> +}
> +
> +void *bpf_map_container_mmapable_alloc(u64 size, int numa_node, u32 align,
> + u32 offset)
> +{
> + struct bpf_map *map;
> + void *container;
> + void *ptr;
> +
> + /* kmalloc'ed memory can't be mmap'ed, use explicit vmalloc */
> + ptr = __bpf_map_area_alloc(size, numa_node, true);
> + if (!ptr)
> + return NULL;
> +
> + container = ptr + align - offset;
> + map = (struct bpf_map *)container;
> + bpf_map_save_memcg(map);
This is very error prone.
I don't think the container concept is necessary.
bpf_map_area_alloc() can just take extra memcg_fd argument.
> +
> + return ptr;
> +}
> +
> +void bpf_map_container_free(void *container)
> +{
> + struct bpf_map *map;
> +
> + if (!container)
> + return;
> +
> + map = (struct bpf_map *)container;
> + bpf_map_release_memcg(map);
> +
> + kvfree(container);
> +}
> +
> static int bpf_map_kptr_off_cmp(const void *a, const void *b)
> {
> const struct bpf_map_value_off_desc *off_desc1 = a, *off_desc2 = b;
> --
> 2.17.1
>
