On Tue, Aug 2, 2022 at 12:58 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> 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.
>
Got it. I will change it.
--
Regards
Yafang
