On Thu, 24 Oct 2019 15:11:40 +0200
Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
> From: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>
> This adds support to libbpf for setting map pinning information as part of
> the BTF map declaration. We introduce a version new
> bpf_object__map_pin_opts() function to pin maps based on this setting, as
> well as a getter and setter function for the pin information that callers
> can use after map load.
>
> The pinning type currently only supports a single PIN_BY_NAME mode, where
> each map will be pinned by its name in a path that can be overridden, but
> defaults to /sys/fs/bpf.
>
> The pinning options supports a 'pin_all' setting, which corresponds to the
> old bpf_object__map_pin() function with an explicit path. In addition, the
> function now defaults to just skipping over maps that are already
> pinned (since the previous commit started recording this in struct
> bpf_map). This behaviour can be turned off with the 'no_skip_pinned' option.
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> ---
> tools/lib/bpf/bpf_helpers.h | 6 ++
> tools/lib/bpf/libbpf.c | 134 ++++++++++++++++++++++++++++++++++---------
> tools/lib/bpf/libbpf.h | 26 ++++++++
> tools/lib/bpf/libbpf.map | 3 +
> 4 files changed, 142 insertions(+), 27 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index 2203595f38c3..0c7d28292898 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -38,4 +38,10 @@ struct bpf_map_def {
> unsigned int map_flags;
> };
>
> +enum libbpf_pin_type {
> + LIBBPF_PIN_NONE,
> + /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
> + LIBBPF_PIN_BY_NAME,
> +};
> +
> #endif
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 848e6710b8e6..179c9911458d 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -226,6 +226,7 @@ struct bpf_map {
> void *priv;
> bpf_map_clear_priv_t clear_priv;
> enum libbpf_map_type libbpf_type;
> + enum libbpf_pin_type pinning;
> char *pin_path;
> bool pinned;
> };
> @@ -1271,6 +1272,22 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
> }
> map->def.value_size = sz;
> map->btf_value_type_id = t->type;
> + } else if (strcmp(name, "pinning") == 0) {
> + __u32 val;
> +
> + if (!get_map_field_int(map_name, obj->btf, def, m,
> + &val))
> + return -EINVAL;
> + pr_debug("map '%s': found pinning = %u.\n",
> + map_name, val);
> +
> + if (val != LIBBPF_PIN_NONE &&
> + val != LIBBPF_PIN_BY_NAME) {
> + pr_warning("map '%s': invalid pinning value %u.\n",
> + map_name, val);
> + return -EINVAL;
> + }
> + map->pinning = val;
> } else {
> if (strict) {
> pr_warning("map '%s': unknown field '%s'.\n",
[...]
How does this prepare for being compatible with iproute2 pinning?
iproute2 have these defines (in include/bpf_elf.h):
/* Object pinning settings */
#define PIN_NONE 0
#define PIN_OBJECT_NS 1
#define PIN_GLOBAL_NS 2
I do know above strcmp(name, "pinning") look at BTF info 'name' and not
directly at the ELF struct for maps. I don't know enough about BTF
(yet), but won't BTF automatically create a "pinning" info 'name' ???
(with above defines as content/values)
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
>From above enum:
LIBBPF_PIN_BY_NAME = 1
iproute2 ELF map struct:
/* ELF map definition */
struct bpf_elf_map {
__u32 type;
__u32 size_key;
__u32 size_value;
__u32 max_elem;
__u32 flags;
__u32 id;
__u32 pinning;
__u32 inner_id;
__u32 inner_idx;
};
